WSL2-Linux-Kernel/kernel/cgroup.c

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Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/*
* Generic process-grouping system.
*
* Based originally on the cpuset system, extracted by Paul Menage
* Copyright (C) 2006 Google, Inc
*
cgroup: implement eventfd-based generic API for notifications This patchset introduces eventfd-based API for notifications in cgroups and implements memory notifications on top of it. It uses statistics in memory controler to track memory usage. Output of time(1) on building kernel on tmpfs: Root cgroup before changes: make -j2 506.37 user 60.93s system 193% cpu 4:52.77 total Non-root cgroup before changes: make -j2 507.14 user 62.66s system 193% cpu 4:54.74 total Root cgroup after changes (0 thresholds): make -j2 507.13 user 62.20s system 193% cpu 4:53.55 total Non-root cgroup after changes (0 thresholds): make -j2 507.70 user 64.20s system 193% cpu 4:55.70 total Root cgroup after changes (1 thresholds, never crossed): make -j2 506.97 user 62.20s system 193% cpu 4:53.90 total Non-root cgroup after changes (1 thresholds, never crossed): make -j2 507.55 user 64.08s system 193% cpu 4:55.63 total This patch: Introduce the write-only file "cgroup.event_control" in every cgroup. To register new notification handler you need: - create an eventfd; - open a control file to be monitored. Callbacks register_event() and unregister_event() must be defined for the control file; - write "<event_fd> <control_fd> <args>" to cgroup.event_control. Interpretation of args is defined by control file implementation; eventfd will be woken up by control file implementation or when the cgroup is removed. To unregister notification handler just close eventfd. If you need notification functionality for a control file you have to implement callbacks register_event() and unregister_event() in the struct cftype. [kamezawa.hiroyu@jp.fujitsu.com: Kconfig fix] Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Paul Menage <menage@google.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Dan Malek <dan@embeddedalley.com> Cc: Vladislav Buzov <vbuzov@embeddedalley.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Alexander Shishkin <virtuoso@slind.org> Cc: Davide Libenzi <davidel@xmailserver.org> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-11 02:22:20 +03:00
* Notifications support
* Copyright (C) 2009 Nokia Corporation
* Author: Kirill A. Shutemov
*
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
* Copyright notices from the original cpuset code:
* --------------------------------------------------
* Copyright (C) 2003 BULL SA.
* Copyright (C) 2004-2006 Silicon Graphics, Inc.
*
* Portions derived from Patrick Mochel's sysfs code.
* sysfs is Copyright (c) 2001-3 Patrick Mochel
*
* 2003-10-10 Written by Simon Derr.
* 2003-10-22 Updates by Stephen Hemminger.
* 2004 May-July Rework by Paul Jackson.
* ---------------------------------------------------
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file COPYING in the main directory of the Linux
* distribution for more details.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
#include <linux/cgroup.h>
cgroupfs: use init_cred when populating new cgroupfs mount We recently found that in some configurations SELinux was blocking the ability for cgroupfs to be mounted. The reason for this is because cgroupfs creates files and directories during the get_sb() call and also uses lookup_one_len() during that same get_sb() call. This is a problem since the security subsystem cannot initialize the superblock and the inodes in that filesystem until after the get_sb() call returns. Thus we leave the inodes in an unitialized state during get_sb(). For the vast majority of filesystems this is not an issue, but since cgroupfs uses lookup_on_len() it does search permission checks on the directories in the path it walks. Since the inode security state is not set up SELinux does these checks as if the inodes were 'unlabeled.' Many 'normal' userspace process do not have permission to interact with unlabeled inodes. The solution presented here is to do the permission checks of path walk and inode creation as the kernel rather than as the task that called mount. Since the kernel has permission to read/write/create unlabeled inodes the get_sb() call will complete successfully and the SELinux code will be able to initialize the superblock and those inodes created during the get_sb() call. This appears to be the same solution used by other filesystems such as devtmpfs to solve the same issue and should thus have no negative impact on other LSMs which currently work. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Paul Menage <menage@google.com> Signed-off-by: James Morris <jmorris@namei.org>
2011-06-02 15:20:51 +04:00
#include <linux/cred.h>
#include <linux/ctype.h>
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
#include <linux/errno.h>
cgroupfs: use init_cred when populating new cgroupfs mount We recently found that in some configurations SELinux was blocking the ability for cgroupfs to be mounted. The reason for this is because cgroupfs creates files and directories during the get_sb() call and also uses lookup_one_len() during that same get_sb() call. This is a problem since the security subsystem cannot initialize the superblock and the inodes in that filesystem until after the get_sb() call returns. Thus we leave the inodes in an unitialized state during get_sb(). For the vast majority of filesystems this is not an issue, but since cgroupfs uses lookup_on_len() it does search permission checks on the directories in the path it walks. Since the inode security state is not set up SELinux does these checks as if the inodes were 'unlabeled.' Many 'normal' userspace process do not have permission to interact with unlabeled inodes. The solution presented here is to do the permission checks of path walk and inode creation as the kernel rather than as the task that called mount. Since the kernel has permission to read/write/create unlabeled inodes the get_sb() call will complete successfully and the SELinux code will be able to initialize the superblock and those inodes created during the get_sb() call. This appears to be the same solution used by other filesystems such as devtmpfs to solve the same issue and should thus have no negative impact on other LSMs which currently work. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Paul Menage <menage@google.com> Signed-off-by: James Morris <jmorris@namei.org>
2011-06-02 15:20:51 +04:00
#include <linux/init_task.h>
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/magic.h>
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/proc_fs.h>
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
#include <linux/rcupdate.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/percpu-rwsem.h>
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
#include <linux/string.h>
#include <linux/sort.h>
#include <linux/kmod.h>
Add cgroupstats This patch is inspired by the discussion at http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263. The patch is on top of 2.6.21-mm1 with Paul's cgroups v9 patches (forward ported) This patch implements per cgroup statistics infrastructure and re-uses code from the taskstats interface. A new set of cgroup operations are registered with commands and attributes. It should be very easy to *extend* per cgroup statistics, by adding members to the cgroupstats structure. The current model for cgroupstats is a pull, a push model (to post statistics on interesting events), should be very easy to add. Currently user space requests for statistics by passing the cgroup file descriptor. Statistics about the state of all the tasks in the cgroup is returned to user space. TODO's/NOTE: This patch provides an infrastructure for implementing cgroup statistics. Based on the needs of each controller, we can incrementally add more statistics, event based support for notification of statistics, accumulation of taskstats into cgroup statistics in the future. Sample output # ./cgroupstats -C /cgroup/a sleeping 2, blocked 0, running 1, stopped 0, uninterruptible 0 # ./cgroupstats -C /cgroup/ sleeping 154, blocked 0, running 0, stopped 0, uninterruptible 0 If the approach looks good, I'll enhance and post the user space utility for the same Feedback, comments, test results are always welcome! [akpm@linux-foundation.org: build fix] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:44 +04:00
#include <linux/delayacct.h>
#include <linux/cgroupstats.h>
#include <linux/hashtable.h>
#include <linux/pid_namespace.h>
#include <linux/idr.h>
#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
#include <linux/kthread.h>
#include <linux/delay.h>
#include <linux/atomic.h>
#include <linux/cpuset.h>
sock, cgroup: add sock->sk_cgroup In cgroup v1, dealing with cgroup membership was difficult because the number of membership associations was unbound. As a result, cgroup v1 grew several controllers whose primary purpose is either tagging membership or pull in configuration knobs from other subsystems so that cgroup membership test can be avoided. net_cls and net_prio controllers are examples of the latter. They allow configuring network-specific attributes from cgroup side so that network subsystem can avoid testing cgroup membership; unfortunately, these are not only cumbersome but also problematic. Both net_cls and net_prio aren't properly hierarchical. Both inherit configuration from the parent on creation but there's no interaction afterwards. An ancestor doesn't restrict the behavior in its subtree in anyway and configuration changes aren't propagated downwards. Especially when combined with cgroup delegation, this is problematic because delegatees can mess up whatever network configuration implemented at the system level. net_prio would allow the delegatees to set whatever priority value regardless of CAP_NET_ADMIN and net_cls the same for classid. While it is possible to solve these issues from controller side by implementing hierarchical allowable ranges in both controllers, it would involve quite a bit of complexity in the controllers and further obfuscate network configuration as it becomes even more difficult to tell what's actually being configured looking from the network side. While not much can be done for v1 at this point, as membership handling is sane on cgroup v2, it'd be better to make cgroup matching behave like other network matches and classifiers than introducing further complications. In preparation, this patch updates sock->sk_cgrp_data handling so that it points to the v2 cgroup that sock was created in until either net_prio or net_cls is used. Once either of the two is used, sock->sk_cgrp_data reverts to its previous role of carrying prioidx and classid. This is to avoid adding yet another cgroup related field to struct sock. As the mode switching can happen at most once per boot, the switching mechanism is aimed at lowering hot path overhead. It may leak a finite, likely small, number of cgroup refs and report spurious prioidx or classid on switching; however, dynamic updates of prioidx and classid have always been racy and lossy - socks between creation and fd installation are never updated, config changes don't update existing sockets at all, and prioidx may index with dead and recycled cgroup IDs. Non-critical inaccuracies from small race windows won't make any noticeable difference. This patch doesn't make use of the pointer yet. The following patch will implement netfilter match for cgroup2 membership. v2: Use sock_cgroup_data to avoid inflating struct sock w/ another cgroup specific field. v3: Add comments explaining why sock_data_prioidx() and sock_data_classid() use different fallback values. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Daniel Wagner <daniel.wagner@bmw-carit.de> CC: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-08 01:38:53 +03:00
#include <net/sock.h>
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
2013-11-29 19:42:58 +04:00
/*
* pidlists linger the following amount before being destroyed. The goal
* is avoiding frequent destruction in the middle of consecutive read calls
* Expiring in the middle is a performance problem not a correctness one.
* 1 sec should be enough.
*/
#define CGROUP_PIDLIST_DESTROY_DELAY HZ
#define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
MAX_CFTYPE_NAME + 2)
/*
* cgroup_mutex is the master lock. Any modification to cgroup or its
* hierarchy must be performed while holding it.
*
* css_set_lock protects task->cgroups pointer, the list of css_set
* objects, and the chain of tasks off each css_set.
*
* These locks are exported if CONFIG_PROVE_RCU so that accessors in
* cgroup.h can use them for lockdep annotations.
*/
#ifdef CONFIG_PROVE_RCU
DEFINE_MUTEX(cgroup_mutex);
DEFINE_SPINLOCK(css_set_lock);
EXPORT_SYMBOL_GPL(cgroup_mutex);
EXPORT_SYMBOL_GPL(css_set_lock);
#else
static DEFINE_MUTEX(cgroup_mutex);
static DEFINE_SPINLOCK(css_set_lock);
#endif
/*
* Protects cgroup_idr and css_idr so that IDs can be released without
* grabbing cgroup_mutex.
*/
static DEFINE_SPINLOCK(cgroup_idr_lock);
/*
* Protects cgroup_file->kn for !self csses. It synchronizes notifications
* against file removal/re-creation across css hiding.
*/
static DEFINE_SPINLOCK(cgroup_file_kn_lock);
/*
* Protects cgroup_subsys->release_agent_path. Modifying it also requires
* cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
*/
static DEFINE_SPINLOCK(release_agent_path_lock);
struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
#define cgroup_assert_mutex_or_rcu_locked() \
RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
!lockdep_is_held(&cgroup_mutex), \
"cgroup_mutex or RCU read lock required");
cgroup: use a dedicated workqueue for cgroup destruction Since be44562613851 ("cgroup: remove synchronize_rcu() from cgroup_diput()"), cgroup destruction path makes use of workqueue. css freeing is performed from a work item from that point on and a later commit, ea15f8ccdb430 ("cgroup: split cgroup destruction into two steps"), moves css offlining to workqueue too. As cgroup destruction isn't depended upon for memory reclaim, the destruction work items were put on the system_wq; unfortunately, some controller may block in the destruction path for considerable duration while holding cgroup_mutex. As large part of destruction path is synchronized through cgroup_mutex, when combined with high rate of cgroup removals, this has potential to fill up system_wq's max_active of 256. Also, it turns out that memcg's css destruction path ends up queueing and waiting for work items on system_wq through work_on_cpu(). If such operation happens while system_wq is fully occupied by cgroup destruction work items, work_on_cpu() can't make forward progress because system_wq is full and other destruction work items on system_wq can't make forward progress because the work item waiting for work_on_cpu() is holding cgroup_mutex, leading to deadlock. This can be fixed by queueing destruction work items on a separate workqueue. This patch creates a dedicated workqueue - cgroup_destroy_wq - for this purpose. As these work items shouldn't have inter-dependencies and mostly serialized by cgroup_mutex anyway, giving high concurrency level doesn't buy anything and the workqueue's @max_active is set to 1 so that destruction work items are executed one by one on each CPU. Hugh Dickins: Because cgroup_init() is run before init_workqueues(), cgroup_destroy_wq can't be allocated from cgroup_init(). Do it from a separate core_initcall(). In the future, we probably want to reorder so that workqueue init happens before cgroup_init(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Hugh Dickins <hughd@google.com> Reported-by: Shawn Bohrer <shawn.bohrer@gmail.com> Link: http://lkml.kernel.org/r/20131111220626.GA7509@sbohrermbp13-local.rgmadvisors.com Link: http://lkml.kernel.org/g/alpine.LNX.2.00.1310301606080.2333@eggly.anvils Cc: stable@vger.kernel.org # v3.9+
2013-11-23 02:14:39 +04:00
/*
* cgroup destruction makes heavy use of work items and there can be a lot
* of concurrent destructions. Use a separate workqueue so that cgroup
* destruction work items don't end up filling up max_active of system_wq
* which may lead to deadlock.
*/
static struct workqueue_struct *cgroup_destroy_wq;
2013-11-29 19:42:58 +04:00
/*
* pidlist destructions need to be flushed on cgroup destruction. Use a
* separate workqueue as flush domain.
*/
static struct workqueue_struct *cgroup_pidlist_destroy_wq;
/* generate an array of cgroup subsystem pointers */
cgroup: clean up cgroup_subsys names and initialization cgroup_subsys is a bit messier than it needs to be. * The name of a subsys can be different from its internal identifier defined in cgroup_subsys.h. Most subsystems use the matching name but three - cpu, memory and perf_event - use different ones. * cgroup_subsys_id enums are postfixed with _subsys_id and each cgroup_subsys is postfixed with _subsys. cgroup.h is widely included throughout various subsystems, it doesn't and shouldn't have claim on such generic names which don't have any qualifier indicating that they belong to cgroup. * cgroup_subsys->subsys_id should always equal the matching cgroup_subsys_id enum; however, we require each controller to initialize it and then BUG if they don't match, which is a bit silly. This patch cleans up cgroup_subsys names and initialization by doing the followings. * cgroup_subsys_id enums are now postfixed with _cgrp_id, and each cgroup_subsys with _cgrp_subsys. * With the above, renaming subsys identifiers to match the userland visible names doesn't cause any naming conflicts. All non-matching identifiers are renamed to match the official names. cpu_cgroup -> cpu mem_cgroup -> memory perf -> perf_event * controllers no longer need to initialize ->subsys_id and ->name. They're generated in cgroup core and set automatically during boot. * Redundant cgroup_subsys declarations removed. * While updating BUG_ON()s in cgroup_init_early(), convert them to WARN()s. BUGging that early during boot is stupid - the kernel can't print anything, even through serial console and the trap handler doesn't even link stack frame properly for back-tracing. This patch doesn't introduce any behavior changes. v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs classid handling into core"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: "David S. Miller" <davem@davemloft.net> Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Ingo Molnar <mingo@redhat.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Thomas Graf <tgraf@suug.ch>
2014-02-08 19:36:58 +04:00
#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
static struct cgroup_subsys *cgroup_subsys[] = {
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
#include <linux/cgroup_subsys.h>
};
cgroup: clean up cgroup_subsys names and initialization cgroup_subsys is a bit messier than it needs to be. * The name of a subsys can be different from its internal identifier defined in cgroup_subsys.h. Most subsystems use the matching name but three - cpu, memory and perf_event - use different ones. * cgroup_subsys_id enums are postfixed with _subsys_id and each cgroup_subsys is postfixed with _subsys. cgroup.h is widely included throughout various subsystems, it doesn't and shouldn't have claim on such generic names which don't have any qualifier indicating that they belong to cgroup. * cgroup_subsys->subsys_id should always equal the matching cgroup_subsys_id enum; however, we require each controller to initialize it and then BUG if they don't match, which is a bit silly. This patch cleans up cgroup_subsys names and initialization by doing the followings. * cgroup_subsys_id enums are now postfixed with _cgrp_id, and each cgroup_subsys with _cgrp_subsys. * With the above, renaming subsys identifiers to match the userland visible names doesn't cause any naming conflicts. All non-matching identifiers are renamed to match the official names. cpu_cgroup -> cpu mem_cgroup -> memory perf -> perf_event * controllers no longer need to initialize ->subsys_id and ->name. They're generated in cgroup core and set automatically during boot. * Redundant cgroup_subsys declarations removed. * While updating BUG_ON()s in cgroup_init_early(), convert them to WARN()s. BUGging that early during boot is stupid - the kernel can't print anything, even through serial console and the trap handler doesn't even link stack frame properly for back-tracing. This patch doesn't introduce any behavior changes. v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs classid handling into core"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: "David S. Miller" <davem@davemloft.net> Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Ingo Molnar <mingo@redhat.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Thomas Graf <tgraf@suug.ch>
2014-02-08 19:36:58 +04:00
#undef SUBSYS
/* array of cgroup subsystem names */
#define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
static const char *cgroup_subsys_name[] = {
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
#include <linux/cgroup_subsys.h>
};
cgroup: clean up cgroup_subsys names and initialization cgroup_subsys is a bit messier than it needs to be. * The name of a subsys can be different from its internal identifier defined in cgroup_subsys.h. Most subsystems use the matching name but three - cpu, memory and perf_event - use different ones. * cgroup_subsys_id enums are postfixed with _subsys_id and each cgroup_subsys is postfixed with _subsys. cgroup.h is widely included throughout various subsystems, it doesn't and shouldn't have claim on such generic names which don't have any qualifier indicating that they belong to cgroup. * cgroup_subsys->subsys_id should always equal the matching cgroup_subsys_id enum; however, we require each controller to initialize it and then BUG if they don't match, which is a bit silly. This patch cleans up cgroup_subsys names and initialization by doing the followings. * cgroup_subsys_id enums are now postfixed with _cgrp_id, and each cgroup_subsys with _cgrp_subsys. * With the above, renaming subsys identifiers to match the userland visible names doesn't cause any naming conflicts. All non-matching identifiers are renamed to match the official names. cpu_cgroup -> cpu mem_cgroup -> memory perf -> perf_event * controllers no longer need to initialize ->subsys_id and ->name. They're generated in cgroup core and set automatically during boot. * Redundant cgroup_subsys declarations removed. * While updating BUG_ON()s in cgroup_init_early(), convert them to WARN()s. BUGging that early during boot is stupid - the kernel can't print anything, even through serial console and the trap handler doesn't even link stack frame properly for back-tracing. This patch doesn't introduce any behavior changes. v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs classid handling into core"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: "David S. Miller" <davem@davemloft.net> Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Ingo Molnar <mingo@redhat.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Thomas Graf <tgraf@suug.ch>
2014-02-08 19:36:58 +04:00
#undef SUBSYS
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */
#define SUBSYS(_x) \
DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \
DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \
EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \
EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key);
#include <linux/cgroup_subsys.h>
#undef SUBSYS
#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key,
static struct static_key_true *cgroup_subsys_enabled_key[] = {
#include <linux/cgroup_subsys.h>
};
#undef SUBSYS
#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key,
static struct static_key_true *cgroup_subsys_on_dfl_key[] = {
#include <linux/cgroup_subsys.h>
};
#undef SUBSYS
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/*
* The default hierarchy, reserved for the subsystems that are otherwise
* unattached - it never has more than a single cgroup, and all tasks are
* part of that cgroup.
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
*/
2014-03-19 18:23:55 +04:00
struct cgroup_root cgrp_dfl_root;
EXPORT_SYMBOL_GPL(cgrp_dfl_root);
2014-03-19 18:23:55 +04:00
/*
* The default hierarchy always exists but is hidden until mounted for the
* first time. This is for backward compatibility.
*/
static bool cgrp_dfl_visible;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* Controllers blocked by the commandline in v1 */
static u16 cgroup_no_v1_mask;
/* some controllers are not supported in the default hierarchy */
static u16 cgrp_dfl_inhibit_ss_mask;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* The list of hierarchy roots */
static LIST_HEAD(cgroup_roots);
static int cgroup_root_count;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* hierarchy ID allocation and mapping, protected by cgroup_mutex */
static DEFINE_IDR(cgroup_hierarchy_idr);
/*
* Assign a monotonically increasing serial number to csses. It guarantees
* cgroups with bigger numbers are newer than those with smaller numbers.
* Also, as csses are always appended to the parent's ->children list, it
* guarantees that sibling csses are always sorted in the ascending serial
* number order on the list. Protected by cgroup_mutex.
*/
static u64 css_serial_nr_next = 1;
/*
* These bitmask flags indicate whether tasks in the fork and exit paths have
* fork/exit handlers to call. This avoids us having to do extra work in the
* fork/exit path to check which subsystems have fork/exit callbacks.
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
*/
static u16 have_fork_callback __read_mostly;
static u16 have_exit_callback __read_mostly;
static u16 have_free_callback __read_mostly;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* Ditto for the can_fork callback. */
static u16 have_canfork_callback __read_mostly;
static struct file_system_type cgroup2_fs_type;
static struct cftype cgroup_dfl_base_files[];
static struct cftype cgroup_legacy_base_files[];
static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
static void css_task_iter_advance(struct css_task_iter *it);
static int cgroup_destroy_locked(struct cgroup *cgrp);
static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
struct cgroup_subsys *ss);
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
static void css_release(struct percpu_ref *ref);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
static void kill_css(struct cgroup_subsys_state *css);
static int cgroup_addrm_files(struct cgroup_subsys_state *css,
struct cgroup *cgrp, struct cftype cfts[],
bool is_add);
/**
* cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID
* @ssid: subsys ID of interest
*
* cgroup_subsys_enabled() can only be used with literal subsys names which
* is fine for individual subsystems but unsuitable for cgroup core. This
* is slower static_key_enabled() based test indexed by @ssid.
*/
static bool cgroup_ssid_enabled(int ssid)
{
return static_key_enabled(cgroup_subsys_enabled_key[ssid]);
}
static bool cgroup_ssid_no_v1(int ssid)
{
return cgroup_no_v1_mask & (1 << ssid);
}
/**
* cgroup_on_dfl - test whether a cgroup is on the default hierarchy
* @cgrp: the cgroup of interest
*
* The default hierarchy is the v2 interface of cgroup and this function
* can be used to test whether a cgroup is on the default hierarchy for
* cases where a subsystem should behave differnetly depending on the
* interface version.
*
* The set of behaviors which change on the default hierarchy are still
* being determined and the mount option is prefixed with __DEVEL__.
*
* List of changed behaviors:
*
* - Mount options "noprefix", "xattr", "clone_children", "release_agent"
* and "name" are disallowed.
*
* - When mounting an existing superblock, mount options should match.
*
* - Remount is disallowed.
*
* - rename(2) is disallowed.
*
* - "tasks" is removed. Everything should be at process granularity. Use
* "cgroup.procs" instead.
*
* - "cgroup.procs" is not sorted. pids will be unique unless they got
* recycled inbetween reads.
*
* - "release_agent" and "notify_on_release" are removed. Replacement
* notification mechanism will be implemented.
*
* - "cgroup.clone_children" is removed.
*
* - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
* and its descendants contain no task; otherwise, 1. The file also
* generates kernfs notification which can be monitored through poll and
* [di]notify when the value of the file changes.
*
* - cpuset: tasks will be kept in empty cpusets when hotplug happens and
* take masks of ancestors with non-empty cpus/mems, instead of being
* moved to an ancestor.
*
* - cpuset: a task can be moved into an empty cpuset, and again it takes
* masks of ancestors.
*
* - memcg: use_hierarchy is on by default and the cgroup file for the flag
* is not created.
*
* - blkcg: blk-throttle becomes properly hierarchical.
*
* - debug: disallowed on the default hierarchy.
*/
static bool cgroup_on_dfl(const struct cgroup *cgrp)
{
return cgrp->root == &cgrp_dfl_root;
}
/* IDR wrappers which synchronize using cgroup_idr_lock */
static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end,
gfp_t gfp_mask)
{
int ret;
idr_preload(gfp_mask);
spin_lock_bh(&cgroup_idr_lock);
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd __GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-11-07 03:28:21 +03:00
ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM);
spin_unlock_bh(&cgroup_idr_lock);
idr_preload_end();
return ret;
}
static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id)
{
void *ret;
spin_lock_bh(&cgroup_idr_lock);
ret = idr_replace(idr, ptr, id);
spin_unlock_bh(&cgroup_idr_lock);
return ret;
}
static void cgroup_idr_remove(struct idr *idr, int id)
{
spin_lock_bh(&cgroup_idr_lock);
idr_remove(idr, id);
spin_unlock_bh(&cgroup_idr_lock);
}
static struct cgroup *cgroup_parent(struct cgroup *cgrp)
{
struct cgroup_subsys_state *parent_css = cgrp->self.parent;
if (parent_css)
return container_of(parent_css, struct cgroup, self);
return NULL;
}
/**
* cgroup_css - obtain a cgroup's css for the specified subsystem
* @cgrp: the cgroup of interest
* @ss: the subsystem of interest (%NULL returns @cgrp->self)
*
* Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
* function must be called either under cgroup_mutex or rcu_read_lock() and
* the caller is responsible for pinning the returned css if it wants to
* keep accessing it outside the said locks. This function may return
* %NULL if @cgrp doesn't have @subsys_id enabled.
*/
static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
struct cgroup_subsys *ss)
{
if (ss)
return rcu_dereference_check(cgrp->subsys[ss->id],
cgroup: introduce cgroup_tree_mutex Currently cgroup uses combination of inode->i_mutex'es and cgroup_mutex for synchronization. With the scheduled kernfs conversion, i_mutex'es will be removed. Unfortunately, just using cgroup_mutex isn't possible. All kernfs file and syscall operations, most of which require grabbing cgroup_mutex, will be called with kernfs active ref held and, if we try to perform kernfs removals under cgroup_mutex, it can deadlock as kernfs_remove() tries to drain the target node. Let's introduce a new outer mutex, cgroup_tree_mutex, which protects stuff used during hierarchy changing operations - cftypes and all the operations which may affect the cgroupfs. It also covers css association and iteration. This allows cgroup_css(), for_each_css() and other css iterators to be called under cgroup_tree_mutex. The new mutex will nest above both kernfs's active ref protection and cgroup_mutex. By protecting tree modifications with a separate outer mutex, we can get rid of the forementioned deadlock condition. Actual file additions and removals now require cgroup_tree_mutex instead of cgroup_mutex. Currently, cgroup_tree_mutex is never used without cgroup_mutex; however, we'll soon add hierarchy modification sections which are only protected by cgroup_tree_mutex. In the future, we might want to make the locking more granular by better splitting the coverages of the two mutexes. For now, this should do. v2: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-11 20:52:47 +04:00
lockdep_is_held(&cgroup_mutex));
else
return &cgrp->self;
}
/**
* cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
* @cgrp: the cgroup of interest
* @ss: the subsystem of interest (%NULL returns @cgrp->self)
*
* Similar to cgroup_css() but returns the effective css, which is defined
* as the matching css of the nearest ancestor including self which has @ss
* enabled. If @ss is associated with the hierarchy @cgrp is on, this
* function is guaranteed to return non-NULL css.
*/
static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
struct cgroup_subsys *ss)
{
lockdep_assert_held(&cgroup_mutex);
if (!ss)
return &cgrp->self;
if (!(cgrp->root->subsys_mask & (1 << ss->id)))
return NULL;
/*
* This function is used while updating css associations and thus
* can't test the csses directly. Use ->subtree_ss_mask.
*/
while (cgroup_parent(cgrp) &&
!(cgroup_parent(cgrp)->subtree_ss_mask & (1 << ss->id)))
cgrp = cgroup_parent(cgrp);
return cgroup_css(cgrp, ss);
}
/**
* cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
* @cgrp: the cgroup of interest
* @ss: the subsystem of interest
*
* Find and get the effective css of @cgrp for @ss. The effective css is
* defined as the matching css of the nearest ancestor including self which
* has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
* the root css is returned, so this function always returns a valid css.
* The returned css must be put using css_put().
*/
struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
struct cgroup_subsys *ss)
{
struct cgroup_subsys_state *css;
rcu_read_lock();
do {
css = cgroup_css(cgrp, ss);
if (css && css_tryget_online(css))
goto out_unlock;
cgrp = cgroup_parent(cgrp);
} while (cgrp);
css = init_css_set.subsys[ss->id];
css_get(css);
out_unlock:
rcu_read_unlock();
return css;
}
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* convenient tests for these bits */
static inline bool cgroup_is_dead(const struct cgroup *cgrp)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
return !(cgrp->self.flags & CSS_ONLINE);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
static void cgroup_get(struct cgroup *cgrp)
{
WARN_ON_ONCE(cgroup_is_dead(cgrp));
css_get(&cgrp->self);
}
static bool cgroup_tryget(struct cgroup *cgrp)
{
return css_tryget(&cgrp->self);
}
struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
{
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct cgroup *cgrp = of->kn->parent->priv;
struct cftype *cft = of_cft(of);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
/*
* This is open and unprotected implementation of cgroup_css().
* seq_css() is only called from a kernfs file operation which has
* an active reference on the file. Because all the subsystem
* files are drained before a css is disassociated with a cgroup,
* the matching css from the cgroup's subsys table is guaranteed to
* be and stay valid until the enclosing operation is complete.
*/
if (cft->ss)
return rcu_dereference_raw(cgrp->subsys[cft->ss->id]);
else
return &cgrp->self;
}
EXPORT_SYMBOL_GPL(of_css);
static int notify_on_release(const struct cgroup *cgrp)
{
return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
}
/**
* for_each_css - iterate all css's of a cgroup
* @css: the iteration cursor
* @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
* @cgrp: the target cgroup to iterate css's of
*
* Should be called under cgroup_[tree_]mutex.
*/
#define for_each_css(css, ssid, cgrp) \
for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
if (!((css) = rcu_dereference_check( \
(cgrp)->subsys[(ssid)], \
lockdep_is_held(&cgroup_mutex)))) { } \
else
/**
* for_each_e_css - iterate all effective css's of a cgroup
* @css: the iteration cursor
* @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
* @cgrp: the target cgroup to iterate css's of
*
* Should be called under cgroup_[tree_]mutex.
*/
#define for_each_e_css(css, ssid, cgrp) \
for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \
; \
else
/**
* for_each_subsys - iterate all enabled cgroup subsystems
* @ss: the iteration cursor
* @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
*/
#define for_each_subsys(ss, ssid) \
for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
(((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
/**
* do_each_subsys_mask - filter for_each_subsys with a bitmask
* @ss: the iteration cursor
* @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
* @ss_mask: the bitmask
*
* The block will only run for cases where the ssid-th bit (1 << ssid) of
* @ss_mask is set.
*/
#define do_each_subsys_mask(ss, ssid, ss_mask) do { \
unsigned long __ss_mask = (ss_mask); \
if (!CGROUP_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \
(ssid) = 0; \
break; \
} \
for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \
(ss) = cgroup_subsys[ssid]; \
{
#define while_each_subsys_mask() \
} \
} \
} while (false)
/* iterate across the hierarchies */
#define for_each_root(root) \
list_for_each_entry((root), &cgroup_roots, root_list)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
/* iterate over child cgrps, lock should be held throughout iteration */
#define cgroup_for_each_live_child(child, cgrp) \
list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
if (({ lockdep_assert_held(&cgroup_mutex); \
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
cgroup_is_dead(child); })) \
; \
else
static void cgroup_release_agent(struct work_struct *work);
static void check_for_release(struct cgroup *cgrp);
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
/*
* A cgroup can be associated with multiple css_sets as different tasks may
* belong to different cgroups on different hierarchies. In the other
* direction, a css_set is naturally associated with multiple cgroups.
* This M:N relationship is represented by the following link structure
* which exists for each association and allows traversing the associations
* from both sides.
*/
struct cgrp_cset_link {
/* the cgroup and css_set this link associates */
struct cgroup *cgrp;
struct css_set *cset;
/* list of cgrp_cset_links anchored at cgrp->cset_links */
struct list_head cset_link;
/* list of cgrp_cset_links anchored at css_set->cgrp_links */
struct list_head cgrp_link;
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
};
/*
* The default css_set - used by init and its children prior to any
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
* hierarchies being mounted. It contains a pointer to the root state
* for each subsystem. Also used to anchor the list of css_sets. Not
* reference-counted, to improve performance when child cgroups
* haven't been created.
*/
struct css_set init_css_set = {
.refcount = ATOMIC_INIT(1),
.cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links),
.tasks = LIST_HEAD_INIT(init_css_set.tasks),
.mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks),
.mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node),
.mg_node = LIST_HEAD_INIT(init_css_set.mg_node),
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
.task_iters = LIST_HEAD_INIT(init_css_set.task_iters),
};
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
static int css_set_count = 1; /* 1 for init_css_set */
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
/**
* css_set_populated - does a css_set contain any tasks?
* @cset: target css_set
*/
static bool css_set_populated(struct css_set *cset)
{
lockdep_assert_held(&css_set_lock);
return !list_empty(&cset->tasks) || !list_empty(&cset->mg_tasks);
}
cgroup: implement cgroup.populated for the default hierarchy cgroup users often need a way to determine when a cgroup's subhierarchy becomes empty so that it can be cleaned up. cgroup currently provides release_agent for it; unfortunately, this mechanism is riddled with issues. * It delivers events by forking and execing a userland binary specified as the release_agent. This is a long deprecated method of notification delivery. It's extremely heavy, slow and cumbersome to integrate with larger infrastructure. * There is single monitoring point at the root. There's no way to delegate management of a subtree. * The event isn't recursive. It triggers when a cgroup doesn't have any tasks or child cgroups. Events for internal nodes trigger only after all children are removed. This again makes it impossible to delegate management of a subtree. * Events are filtered from the kernel side. "notify_on_release" file is used to subscribe to or suppress release event. This is unnecessarily complicated and probably done this way because event delivery itself was expensive. This patch implements interface file "cgroup.populated" which can be used to monitor whether the cgroup's subhierarchy has tasks in it or not. Its value is 0 if there is no task in the cgroup and its descendants; otherwise, 1, and kernfs_notify() notificaiton is triggers when the value changes, which can be monitored through poll and [di]notify. This is a lot ligther and simpler and trivially allows delegating management of subhierarchy - subhierarchy monitoring can block further propgation simply by putting itself or another process in the root of the subhierarchy and monitor events that it's interested in from there without interfering with monitoring higher in the tree. v2: Patch description updated as per Serge. v3: "cgroup.subtree_populated" renamed to "cgroup.populated". The subtree_ prefix was a bit confusing because "cgroup.subtree_control" uses it to denote the tree rooted at the cgroup sans the cgroup itself while the populated state includes the cgroup itself. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Lennart Poettering <lennart@poettering.net>
2014-04-26 02:28:02 +04:00
/**
* cgroup_update_populated - updated populated count of a cgroup
* @cgrp: the target cgroup
* @populated: inc or dec populated count
*
* One of the css_sets associated with @cgrp is either getting its first
* task or losing the last. Update @cgrp->populated_cnt accordingly. The
* count is propagated towards root so that a given cgroup's populated_cnt
* is zero iff the cgroup and all its descendants don't contain any tasks.
cgroup: implement cgroup.populated for the default hierarchy cgroup users often need a way to determine when a cgroup's subhierarchy becomes empty so that it can be cleaned up. cgroup currently provides release_agent for it; unfortunately, this mechanism is riddled with issues. * It delivers events by forking and execing a userland binary specified as the release_agent. This is a long deprecated method of notification delivery. It's extremely heavy, slow and cumbersome to integrate with larger infrastructure. * There is single monitoring point at the root. There's no way to delegate management of a subtree. * The event isn't recursive. It triggers when a cgroup doesn't have any tasks or child cgroups. Events for internal nodes trigger only after all children are removed. This again makes it impossible to delegate management of a subtree. * Events are filtered from the kernel side. "notify_on_release" file is used to subscribe to or suppress release event. This is unnecessarily complicated and probably done this way because event delivery itself was expensive. This patch implements interface file "cgroup.populated" which can be used to monitor whether the cgroup's subhierarchy has tasks in it or not. Its value is 0 if there is no task in the cgroup and its descendants; otherwise, 1, and kernfs_notify() notificaiton is triggers when the value changes, which can be monitored through poll and [di]notify. This is a lot ligther and simpler and trivially allows delegating management of subhierarchy - subhierarchy monitoring can block further propgation simply by putting itself or another process in the root of the subhierarchy and monitor events that it's interested in from there without interfering with monitoring higher in the tree. v2: Patch description updated as per Serge. v3: "cgroup.subtree_populated" renamed to "cgroup.populated". The subtree_ prefix was a bit confusing because "cgroup.subtree_control" uses it to denote the tree rooted at the cgroup sans the cgroup itself while the populated state includes the cgroup itself. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Lennart Poettering <lennart@poettering.net>
2014-04-26 02:28:02 +04:00
*
* @cgrp's interface file "cgroup.populated" is zero if
* @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt
* changes from or to zero, userland is notified that the content of the
* interface file has changed. This can be used to detect when @cgrp and
* its descendants become populated or empty.
*/
static void cgroup_update_populated(struct cgroup *cgrp, bool populated)
{
lockdep_assert_held(&css_set_lock);
cgroup: implement cgroup.populated for the default hierarchy cgroup users often need a way to determine when a cgroup's subhierarchy becomes empty so that it can be cleaned up. cgroup currently provides release_agent for it; unfortunately, this mechanism is riddled with issues. * It delivers events by forking and execing a userland binary specified as the release_agent. This is a long deprecated method of notification delivery. It's extremely heavy, slow and cumbersome to integrate with larger infrastructure. * There is single monitoring point at the root. There's no way to delegate management of a subtree. * The event isn't recursive. It triggers when a cgroup doesn't have any tasks or child cgroups. Events for internal nodes trigger only after all children are removed. This again makes it impossible to delegate management of a subtree. * Events are filtered from the kernel side. "notify_on_release" file is used to subscribe to or suppress release event. This is unnecessarily complicated and probably done this way because event delivery itself was expensive. This patch implements interface file "cgroup.populated" which can be used to monitor whether the cgroup's subhierarchy has tasks in it or not. Its value is 0 if there is no task in the cgroup and its descendants; otherwise, 1, and kernfs_notify() notificaiton is triggers when the value changes, which can be monitored through poll and [di]notify. This is a lot ligther and simpler and trivially allows delegating management of subhierarchy - subhierarchy monitoring can block further propgation simply by putting itself or another process in the root of the subhierarchy and monitor events that it's interested in from there without interfering with monitoring higher in the tree. v2: Patch description updated as per Serge. v3: "cgroup.subtree_populated" renamed to "cgroup.populated". The subtree_ prefix was a bit confusing because "cgroup.subtree_control" uses it to denote the tree rooted at the cgroup sans the cgroup itself while the populated state includes the cgroup itself. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Lennart Poettering <lennart@poettering.net>
2014-04-26 02:28:02 +04:00
do {
bool trigger;
if (populated)
trigger = !cgrp->populated_cnt++;
else
trigger = !--cgrp->populated_cnt;
if (!trigger)
break;
check_for_release(cgrp);
cgroup_file_notify(&cgrp->events_file);
cgrp = cgroup_parent(cgrp);
cgroup: implement cgroup.populated for the default hierarchy cgroup users often need a way to determine when a cgroup's subhierarchy becomes empty so that it can be cleaned up. cgroup currently provides release_agent for it; unfortunately, this mechanism is riddled with issues. * It delivers events by forking and execing a userland binary specified as the release_agent. This is a long deprecated method of notification delivery. It's extremely heavy, slow and cumbersome to integrate with larger infrastructure. * There is single monitoring point at the root. There's no way to delegate management of a subtree. * The event isn't recursive. It triggers when a cgroup doesn't have any tasks or child cgroups. Events for internal nodes trigger only after all children are removed. This again makes it impossible to delegate management of a subtree. * Events are filtered from the kernel side. "notify_on_release" file is used to subscribe to or suppress release event. This is unnecessarily complicated and probably done this way because event delivery itself was expensive. This patch implements interface file "cgroup.populated" which can be used to monitor whether the cgroup's subhierarchy has tasks in it or not. Its value is 0 if there is no task in the cgroup and its descendants; otherwise, 1, and kernfs_notify() notificaiton is triggers when the value changes, which can be monitored through poll and [di]notify. This is a lot ligther and simpler and trivially allows delegating management of subhierarchy - subhierarchy monitoring can block further propgation simply by putting itself or another process in the root of the subhierarchy and monitor events that it's interested in from there without interfering with monitoring higher in the tree. v2: Patch description updated as per Serge. v3: "cgroup.subtree_populated" renamed to "cgroup.populated". The subtree_ prefix was a bit confusing because "cgroup.subtree_control" uses it to denote the tree rooted at the cgroup sans the cgroup itself while the populated state includes the cgroup itself. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Lennart Poettering <lennart@poettering.net>
2014-04-26 02:28:02 +04:00
} while (cgrp);
}
/**
* css_set_update_populated - update populated state of a css_set
* @cset: target css_set
* @populated: whether @cset is populated or depopulated
*
* @cset is either getting the first task or losing the last. Update the
* ->populated_cnt of all associated cgroups accordingly.
*/
static void css_set_update_populated(struct css_set *cset, bool populated)
{
struct cgrp_cset_link *link;
lockdep_assert_held(&css_set_lock);
list_for_each_entry(link, &cset->cgrp_links, cgrp_link)
cgroup_update_populated(link->cgrp, populated);
}
/**
* css_set_move_task - move a task from one css_set to another
* @task: task being moved
* @from_cset: css_set @task currently belongs to (may be NULL)
* @to_cset: new css_set @task is being moved to (may be NULL)
* @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks
*
* Move @task from @from_cset to @to_cset. If @task didn't belong to any
* css_set, @from_cset can be NULL. If @task is being disassociated
* instead of moved, @to_cset can be NULL.
*
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
* This function automatically handles populated_cnt updates and
* css_task_iter adjustments but the caller is responsible for managing
* @from_cset and @to_cset's reference counts.
*/
static void css_set_move_task(struct task_struct *task,
struct css_set *from_cset, struct css_set *to_cset,
bool use_mg_tasks)
{
lockdep_assert_held(&css_set_lock);
if (to_cset && !css_set_populated(to_cset))
css_set_update_populated(to_cset, true);
if (from_cset) {
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
struct css_task_iter *it, *pos;
WARN_ON_ONCE(list_empty(&task->cg_list));
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
/*
* @task is leaving, advance task iterators which are
* pointing to it so that they can resume at the next
* position. Advancing an iterator might remove it from
* the list, use safe walk. See css_task_iter_advance*()
* for details.
*/
list_for_each_entry_safe(it, pos, &from_cset->task_iters,
iters_node)
if (it->task_pos == &task->cg_list)
css_task_iter_advance(it);
list_del_init(&task->cg_list);
if (!css_set_populated(from_cset))
css_set_update_populated(from_cset, false);
} else {
WARN_ON_ONCE(!list_empty(&task->cg_list));
}
if (to_cset) {
/*
* We are synchronized through cgroup_threadgroup_rwsem
* against PF_EXITING setting such that we can't race
* against cgroup_exit() changing the css_set to
* init_css_set and dropping the old one.
*/
WARN_ON_ONCE(task->flags & PF_EXITING);
rcu_assign_pointer(task->cgroups, to_cset);
list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks :
&to_cset->tasks);
}
}
/*
* hash table for cgroup groups. This improves the performance to find
* an existing css_set. This hash doesn't (currently) take into
* account cgroups in empty hierarchies.
*/
#define CSS_SET_HASH_BITS 7
static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
{
unsigned long key = 0UL;
struct cgroup_subsys *ss;
int i;
for_each_subsys(ss, i)
key += (unsigned long)css[i];
key = (key >> 16) ^ key;
return key;
}
static void put_css_set_locked(struct css_set *cset)
{
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
struct cgrp_cset_link *link, *tmp_link;
struct cgroup_subsys *ss;
int ssid;
lockdep_assert_held(&css_set_lock);
if (!atomic_dec_and_test(&cset->refcount))
return;
cgroup: make css_set pin its css's to avoid use-afer-free A css_set represents the relationship between a set of tasks and css's. css_set never pinned the associated css's. This was okay because tasks used to always disassociate immediately (in RCU sense) - either a task is moved to a different css_set or exits and never accesses css_set again. Unfortunately, afcf6c8b7544 ("cgroup: add cgroup_subsys->free() method and use it to fix pids controller") and patches leading up to it made a zombie hold onto its css_set and deref the associated css's on its release. Nothing pins the css's after exit and it might have already been freed leading to use-after-free. general protection fault: 0000 [#1] PREEMPT SMP task: ffffffff81bf2500 ti: ffffffff81be4000 task.ti: ffffffff81be4000 RIP: 0010:[<ffffffff810fa205>] [<ffffffff810fa205>] pids_cancel.constprop.4+0x5/0x40 ... Call Trace: <IRQ> [<ffffffff810fb02d>] ? pids_free+0x3d/0xa0 [<ffffffff810f8893>] cgroup_free+0x53/0xe0 [<ffffffff8104ed62>] __put_task_struct+0x42/0x130 [<ffffffff81053557>] delayed_put_task_struct+0x77/0x130 [<ffffffff810c6b34>] rcu_process_callbacks+0x2f4/0x820 [<ffffffff810c6af3>] ? rcu_process_callbacks+0x2b3/0x820 [<ffffffff81056e54>] __do_softirq+0xd4/0x460 [<ffffffff81057369>] irq_exit+0x89/0xa0 [<ffffffff81876212>] smp_apic_timer_interrupt+0x42/0x50 [<ffffffff818747f4>] apic_timer_interrupt+0x84/0x90 <EOI> ... Code: 5b 5d c3 48 89 df 48 c7 c2 c9 f9 ae 81 48 c7 c6 91 2c ae 81 e8 1d 94 0e 00 31 c0 5b 5d c3 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 <f0> 48 83 87 e0 00 00 00 ff 78 01 c3 80 3d 08 7a c1 00 00 74 02 RIP [<ffffffff810fa205>] pids_cancel.constprop.4+0x5/0x40 RSP <ffff88001fc03e20> ---[ end trace 89a4a4b916b90c49 ]--- Kernel panic - not syncing: Fatal exception in interrupt Kernel Offset: disabled ---[ end Kernel panic - not syncing: Fatal exception in interrupt Fix it by making css_set pin the associate css's until its release. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dave Jones <davej@codemonkey.org.uk> Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Link: http://lkml.kernel.org/g/20151120041836.GA18390@codemonkey.org.uk Link: http://lkml.kernel.org/g/5652D448.3080002@bmw-carit.de Fixes: afcf6c8b7544 ("cgroup: add cgroup_subsys->free() method and use it to fix pids controller")
2015-11-23 22:55:41 +03:00
/* This css_set is dead. unlink it and release cgroup and css refs */
for_each_subsys(ss, ssid) {
list_del(&cset->e_cset_node[ssid]);
cgroup: make css_set pin its css's to avoid use-afer-free A css_set represents the relationship between a set of tasks and css's. css_set never pinned the associated css's. This was okay because tasks used to always disassociate immediately (in RCU sense) - either a task is moved to a different css_set or exits and never accesses css_set again. Unfortunately, afcf6c8b7544 ("cgroup: add cgroup_subsys->free() method and use it to fix pids controller") and patches leading up to it made a zombie hold onto its css_set and deref the associated css's on its release. Nothing pins the css's after exit and it might have already been freed leading to use-after-free. general protection fault: 0000 [#1] PREEMPT SMP task: ffffffff81bf2500 ti: ffffffff81be4000 task.ti: ffffffff81be4000 RIP: 0010:[<ffffffff810fa205>] [<ffffffff810fa205>] pids_cancel.constprop.4+0x5/0x40 ... Call Trace: <IRQ> [<ffffffff810fb02d>] ? pids_free+0x3d/0xa0 [<ffffffff810f8893>] cgroup_free+0x53/0xe0 [<ffffffff8104ed62>] __put_task_struct+0x42/0x130 [<ffffffff81053557>] delayed_put_task_struct+0x77/0x130 [<ffffffff810c6b34>] rcu_process_callbacks+0x2f4/0x820 [<ffffffff810c6af3>] ? rcu_process_callbacks+0x2b3/0x820 [<ffffffff81056e54>] __do_softirq+0xd4/0x460 [<ffffffff81057369>] irq_exit+0x89/0xa0 [<ffffffff81876212>] smp_apic_timer_interrupt+0x42/0x50 [<ffffffff818747f4>] apic_timer_interrupt+0x84/0x90 <EOI> ... Code: 5b 5d c3 48 89 df 48 c7 c2 c9 f9 ae 81 48 c7 c6 91 2c ae 81 e8 1d 94 0e 00 31 c0 5b 5d c3 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 <f0> 48 83 87 e0 00 00 00 ff 78 01 c3 80 3d 08 7a c1 00 00 74 02 RIP [<ffffffff810fa205>] pids_cancel.constprop.4+0x5/0x40 RSP <ffff88001fc03e20> ---[ end trace 89a4a4b916b90c49 ]--- Kernel panic - not syncing: Fatal exception in interrupt Kernel Offset: disabled ---[ end Kernel panic - not syncing: Fatal exception in interrupt Fix it by making css_set pin the associate css's until its release. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dave Jones <davej@codemonkey.org.uk> Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Link: http://lkml.kernel.org/g/20151120041836.GA18390@codemonkey.org.uk Link: http://lkml.kernel.org/g/5652D448.3080002@bmw-carit.de Fixes: afcf6c8b7544 ("cgroup: add cgroup_subsys->free() method and use it to fix pids controller")
2015-11-23 22:55:41 +03:00
css_put(cset->subsys[ssid]);
}
hash_del(&cset->hlist);
css_set_count--;
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) {
list_del(&link->cset_link);
list_del(&link->cgrp_link);
if (cgroup_parent(link->cgrp))
cgroup_put(link->cgrp);
kfree(link);
}
kfree_rcu(cset, rcu_head);
}
static void put_css_set(struct css_set *cset)
{
/*
* Ensure that the refcount doesn't hit zero while any readers
* can see it. Similar to atomic_dec_and_lock(), but for an
* rwlock
*/
if (atomic_add_unless(&cset->refcount, -1, 1))
return;
spin_lock_bh(&css_set_lock);
put_css_set_locked(cset);
spin_unlock_bh(&css_set_lock);
}
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
/*
* refcounted get/put for css_set objects
*/
static inline void get_css_set(struct css_set *cset)
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
{
atomic_inc(&cset->refcount);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
}
/**
* compare_css_sets - helper function for find_existing_css_set().
* @cset: candidate css_set being tested
* @old_cset: existing css_set for a task
* @new_cgrp: cgroup that's being entered by the task
* @template: desired set of css pointers in css_set (pre-calculated)
*
* Returns true if "cset" matches "old_cset" except for the hierarchy
* which "new_cgrp" belongs to, for which it should match "new_cgrp".
*/
static bool compare_css_sets(struct css_set *cset,
struct css_set *old_cset,
struct cgroup *new_cgrp,
struct cgroup_subsys_state *template[])
{
struct list_head *l1, *l2;
/*
* On the default hierarchy, there can be csets which are
* associated with the same set of cgroups but different csses.
* Let's first ensure that csses match.
*/
if (memcmp(template, cset->subsys, sizeof(cset->subsys)))
return false;
/*
* Compare cgroup pointers in order to distinguish between
* different cgroups in hierarchies. As different cgroups may
* share the same effective css, this comparison is always
* necessary.
*/
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
l1 = &cset->cgrp_links;
l2 = &old_cset->cgrp_links;
while (1) {
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
struct cgrp_cset_link *link1, *link2;
struct cgroup *cgrp1, *cgrp2;
l1 = l1->next;
l2 = l2->next;
/* See if we reached the end - both lists are equal length. */
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
if (l1 == &cset->cgrp_links) {
BUG_ON(l2 != &old_cset->cgrp_links);
break;
} else {
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
BUG_ON(l2 == &old_cset->cgrp_links);
}
/* Locate the cgroups associated with these links. */
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link);
link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link);
cgrp1 = link1->cgrp;
cgrp2 = link2->cgrp;
/* Hierarchies should be linked in the same order. */
BUG_ON(cgrp1->root != cgrp2->root);
/*
* If this hierarchy is the hierarchy of the cgroup
* that's changing, then we need to check that this
* css_set points to the new cgroup; if it's any other
* hierarchy, then this css_set should point to the
* same cgroup as the old css_set.
*/
if (cgrp1->root == new_cgrp->root) {
if (cgrp1 != new_cgrp)
return false;
} else {
if (cgrp1 != cgrp2)
return false;
}
}
return true;
}
/**
* find_existing_css_set - init css array and find the matching css_set
* @old_cset: the css_set that we're using before the cgroup transition
* @cgrp: the cgroup that we're moving into
* @template: out param for the new set of csses, should be clear on entry
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
*/
static struct css_set *find_existing_css_set(struct css_set *old_cset,
struct cgroup *cgrp,
struct cgroup_subsys_state *template[])
{
struct cgroup_root *root = cgrp->root;
struct cgroup_subsys *ss;
struct css_set *cset;
unsigned long key;
int i;
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
cgroups: revamp subsys array This patch series provides the ability for cgroup subsystems to be compiled as modules both within and outside the kernel tree. This is mainly useful for classifiers and subsystems that hook into components that are already modules. cls_cgroup and blkio-cgroup serve as the example use cases for this feature. It provides an interface cgroup_load_subsys() and cgroup_unload_subsys() which modular subsystems can use to register and depart during runtime. The net_cls classifier subsystem serves as the example for a subsystem which can be converted into a module using these changes. Patch #1 sets up the subsys[] array so its contents can be dynamic as modules appear and (eventually) disappear. Iterations over the array are modified to handle when subsystems are absent, and the dynamic section of the array is protected by cgroup_mutex. Patch #2 implements an interface for modules to load subsystems, called cgroup_load_subsys, similar to cgroup_init_subsys, and adds a module pointer in struct cgroup_subsys. Patch #3 adds a mechanism for unloading modular subsystems, which includes a more advanced rework of the rudimentary reference counting introduced in patch 2. Patch #4 modifies the net_cls subsystem, which already had some module declarations, to be configurable as a module, which also serves as a simple proof-of-concept. Part of implementing patches 2 and 4 involved updating css pointers in each css_set when the module appears or leaves. In doing this, it was discovered that css_sets always remain linked to the dummy cgroup, regardless of whether or not any subsystems are actually bound to it (i.e., not mounted on an actual hierarchy). The subsystem loading and unloading code therefore should keep in mind the special cases where the added subsystem is the only one in the dummy cgroup (and therefore all css_sets need to be linked back into it) and where the removed subsys was the only one in the dummy cgroup (and therefore all css_sets should be unlinked from it) - however, as all css_sets always stay attached to the dummy cgroup anyway, these cases are ignored. Any fix that addresses this issue should also make sure these cases are addressed in the subsystem loading and unloading code. This patch: Make subsys[] able to be dynamically populated to support modular subsystems This patch reworks the way the subsys[] array is used so that subsystems can register themselves after boot time, and enables the internals of cgroups to be able to handle when subsystems are not present or may appear/disappear. Signed-off-by: Ben Blum <bblum@andrew.cmu.edu> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-11 02:22:07 +03:00
/*
* Build the set of subsystem state objects that we want to see in the
* new css_set. while subsystems can change globally, the entries here
* won't change, so no need for locking.
*/
for_each_subsys(ss, i) {
if (root->subsys_mask & (1UL << i)) {
/*
* @ss is in this hierarchy, so we want the
* effective css from @cgrp.
*/
template[i] = cgroup_e_css(cgrp, ss);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
} else {
/*
* @ss is not in this hierarchy, so we don't want
* to change the css.
*/
template[i] = old_cset->subsys[i];
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
}
}
key = css_set_hash(template);
hash_for_each_possible(css_set_table, cset, hlist, key) {
if (!compare_css_sets(cset, old_cset, cgrp, template))
continue;
/* This css_set matches what we need */
return cset;
}
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
/* No existing cgroup group matched */
return NULL;
}
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
static void free_cgrp_cset_links(struct list_head *links_to_free)
{
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
struct cgrp_cset_link *link, *tmp_link;
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) {
list_del(&link->cset_link);
kfree(link);
}
}
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
/**
* allocate_cgrp_cset_links - allocate cgrp_cset_links
* @count: the number of links to allocate
* @tmp_links: list_head the allocated links are put on
*
* Allocate @count cgrp_cset_link structures and chain them on @tmp_links
* through ->cset_link. Returns 0 on success or -errno.
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
*/
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links)
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
{
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
struct cgrp_cset_link *link;
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
int i;
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
INIT_LIST_HEAD(tmp_links);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
for (i = 0; i < count; i++) {
link = kzalloc(sizeof(*link), GFP_KERNEL);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
if (!link) {
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
free_cgrp_cset_links(tmp_links);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
return -ENOMEM;
}
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
list_add(&link->cset_link, tmp_links);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
}
return 0;
}
/**
* link_css_set - a helper function to link a css_set to a cgroup
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
* @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
* @cset: the css_set to be linked
* @cgrp: the destination cgroup
*/
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
static void link_css_set(struct list_head *tmp_links, struct css_set *cset,
struct cgroup *cgrp)
{
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
struct cgrp_cset_link *link;
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
BUG_ON(list_empty(tmp_links));
if (cgroup_on_dfl(cgrp))
cset->dfl_cgrp = cgrp;
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link);
link->cset = cset;
link->cgrp = cgrp;
cgroup: implement cgroup.populated for the default hierarchy cgroup users often need a way to determine when a cgroup's subhierarchy becomes empty so that it can be cleaned up. cgroup currently provides release_agent for it; unfortunately, this mechanism is riddled with issues. * It delivers events by forking and execing a userland binary specified as the release_agent. This is a long deprecated method of notification delivery. It's extremely heavy, slow and cumbersome to integrate with larger infrastructure. * There is single monitoring point at the root. There's no way to delegate management of a subtree. * The event isn't recursive. It triggers when a cgroup doesn't have any tasks or child cgroups. Events for internal nodes trigger only after all children are removed. This again makes it impossible to delegate management of a subtree. * Events are filtered from the kernel side. "notify_on_release" file is used to subscribe to or suppress release event. This is unnecessarily complicated and probably done this way because event delivery itself was expensive. This patch implements interface file "cgroup.populated" which can be used to monitor whether the cgroup's subhierarchy has tasks in it or not. Its value is 0 if there is no task in the cgroup and its descendants; otherwise, 1, and kernfs_notify() notificaiton is triggers when the value changes, which can be monitored through poll and [di]notify. This is a lot ligther and simpler and trivially allows delegating management of subhierarchy - subhierarchy monitoring can block further propgation simply by putting itself or another process in the root of the subhierarchy and monitor events that it's interested in from there without interfering with monitoring higher in the tree. v2: Patch description updated as per Serge. v3: "cgroup.subtree_populated" renamed to "cgroup.populated". The subtree_ prefix was a bit confusing because "cgroup.subtree_control" uses it to denote the tree rooted at the cgroup sans the cgroup itself while the populated state includes the cgroup itself. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Lennart Poettering <lennart@poettering.net>
2014-04-26 02:28:02 +04:00
/*
* Always add links to the tail of the lists so that the lists are
* in choronological order.
*/
list_move_tail(&link->cset_link, &cgrp->cset_links);
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
list_add_tail(&link->cgrp_link, &cset->cgrp_links);
if (cgroup_parent(cgrp))
cgroup_get(cgrp);
}
/**
* find_css_set - return a new css_set with one cgroup updated
* @old_cset: the baseline css_set
* @cgrp: the cgroup to be updated
*
* Return a new css_set that's equivalent to @old_cset, but with @cgrp
* substituted into the appropriate hierarchy.
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
*/
static struct css_set *find_css_set(struct css_set *old_cset,
struct cgroup *cgrp)
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
{
struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { };
struct css_set *cset;
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
struct list_head tmp_links;
struct cgrp_cset_link *link;
struct cgroup_subsys *ss;
unsigned long key;
int ssid;
lockdep_assert_held(&cgroup_mutex);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
/* First see if we already have a cgroup group that matches
* the desired set */
spin_lock_bh(&css_set_lock);
cset = find_existing_css_set(old_cset, cgrp, template);
if (cset)
get_css_set(cset);
spin_unlock_bh(&css_set_lock);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
if (cset)
return cset;
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
cset = kzalloc(sizeof(*cset), GFP_KERNEL);
if (!cset)
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
return NULL;
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
/* Allocate all the cgrp_cset_link objects that we'll need */
if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) {
kfree(cset);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
return NULL;
}
atomic_set(&cset->refcount, 1);
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
INIT_LIST_HEAD(&cset->cgrp_links);
INIT_LIST_HEAD(&cset->tasks);
cgroup: add css_set->mg_tasks Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, we're going to use task->cg_list during migration too. Instead of building a separate array, target tasks will be linked into a dedicated migration list_head on the owning css_set. Tasks on the migration list are treated the same as tasks on the usual tasks list; however, being on a separate list allows cgroup migration code path to keep track of the target tasks by simply keeping the list of css_sets with tasks being migrated, making unpredictable dynamic allocation unnecessary. In prepartion of such migration path update, this patch introduces css_set->mg_tasks list and updates css_set task iterations so that they walk both css_set->tasks and ->mg_tasks. Note that ->mg_tasks isn't used yet. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
INIT_LIST_HEAD(&cset->mg_tasks);
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
INIT_LIST_HEAD(&cset->mg_preload_node);
cgroup: use css_set->mg_tasks to track target tasks during migration Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, this patch updates the migration path to use task->cg_list to track target tasks. The previous patch already added css_set->mg_tasks and updated iterations in non-migration paths to include them during task migration. This patch updates migration path to actually make use of it. Instead of putting onto a flex_array, each target task is moved from its css_set->tasks list to css_set->mg_tasks and the migration path keeps trace of all the source css_sets and the associated cgroups. Once all source css_sets are determined, the destination css_set for each is determined, linked to the matching source css_set and put on a separate list. To iterate the target tasks, migration path just needs to iterat through either the source or target css_sets, depending on whether migration has been committed or not, and the tasks on their ->mg_tasks lists. cgroup_taskset is updated to contain the list_heads for source and target css_sets and the iteration cursor. cgroup_taskset_*() are accordingly updated to walk through css_sets and their ->mg_tasks. This resolves the above listed issues with moderate additional complexity. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
INIT_LIST_HEAD(&cset->mg_node);
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
INIT_LIST_HEAD(&cset->task_iters);
INIT_HLIST_NODE(&cset->hlist);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
/* Copy the set of subsystem state objects generated in
* find_existing_css_set() */
memcpy(cset->subsys, template, sizeof(cset->subsys));
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
spin_lock_bh(&css_set_lock);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
/* Add reference counts and links from the new css_set. */
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) {
struct cgroup *c = link->cgrp;
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
if (c->root == cgrp->root)
c = cgrp;
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
link_css_set(&tmp_links, cset, c);
}
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
BUG_ON(!list_empty(&tmp_links));
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
css_set_count++;
/* Add @cset to the hash table */
key = css_set_hash(cset->subsys);
hash_add(css_set_table, &cset->hlist, key);
cgroup: make css_set pin its css's to avoid use-afer-free A css_set represents the relationship between a set of tasks and css's. css_set never pinned the associated css's. This was okay because tasks used to always disassociate immediately (in RCU sense) - either a task is moved to a different css_set or exits and never accesses css_set again. Unfortunately, afcf6c8b7544 ("cgroup: add cgroup_subsys->free() method and use it to fix pids controller") and patches leading up to it made a zombie hold onto its css_set and deref the associated css's on its release. Nothing pins the css's after exit and it might have already been freed leading to use-after-free. general protection fault: 0000 [#1] PREEMPT SMP task: ffffffff81bf2500 ti: ffffffff81be4000 task.ti: ffffffff81be4000 RIP: 0010:[<ffffffff810fa205>] [<ffffffff810fa205>] pids_cancel.constprop.4+0x5/0x40 ... Call Trace: <IRQ> [<ffffffff810fb02d>] ? pids_free+0x3d/0xa0 [<ffffffff810f8893>] cgroup_free+0x53/0xe0 [<ffffffff8104ed62>] __put_task_struct+0x42/0x130 [<ffffffff81053557>] delayed_put_task_struct+0x77/0x130 [<ffffffff810c6b34>] rcu_process_callbacks+0x2f4/0x820 [<ffffffff810c6af3>] ? rcu_process_callbacks+0x2b3/0x820 [<ffffffff81056e54>] __do_softirq+0xd4/0x460 [<ffffffff81057369>] irq_exit+0x89/0xa0 [<ffffffff81876212>] smp_apic_timer_interrupt+0x42/0x50 [<ffffffff818747f4>] apic_timer_interrupt+0x84/0x90 <EOI> ... Code: 5b 5d c3 48 89 df 48 c7 c2 c9 f9 ae 81 48 c7 c6 91 2c ae 81 e8 1d 94 0e 00 31 c0 5b 5d c3 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 <f0> 48 83 87 e0 00 00 00 ff 78 01 c3 80 3d 08 7a c1 00 00 74 02 RIP [<ffffffff810fa205>] pids_cancel.constprop.4+0x5/0x40 RSP <ffff88001fc03e20> ---[ end trace 89a4a4b916b90c49 ]--- Kernel panic - not syncing: Fatal exception in interrupt Kernel Offset: disabled ---[ end Kernel panic - not syncing: Fatal exception in interrupt Fix it by making css_set pin the associate css's until its release. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dave Jones <davej@codemonkey.org.uk> Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Link: http://lkml.kernel.org/g/20151120041836.GA18390@codemonkey.org.uk Link: http://lkml.kernel.org/g/5652D448.3080002@bmw-carit.de Fixes: afcf6c8b7544 ("cgroup: add cgroup_subsys->free() method and use it to fix pids controller")
2015-11-23 22:55:41 +03:00
for_each_subsys(ss, ssid) {
struct cgroup_subsys_state *css = cset->subsys[ssid];
list_add_tail(&cset->e_cset_node[ssid],
cgroup: make css_set pin its css's to avoid use-afer-free A css_set represents the relationship between a set of tasks and css's. css_set never pinned the associated css's. This was okay because tasks used to always disassociate immediately (in RCU sense) - either a task is moved to a different css_set or exits and never accesses css_set again. Unfortunately, afcf6c8b7544 ("cgroup: add cgroup_subsys->free() method and use it to fix pids controller") and patches leading up to it made a zombie hold onto its css_set and deref the associated css's on its release. Nothing pins the css's after exit and it might have already been freed leading to use-after-free. general protection fault: 0000 [#1] PREEMPT SMP task: ffffffff81bf2500 ti: ffffffff81be4000 task.ti: ffffffff81be4000 RIP: 0010:[<ffffffff810fa205>] [<ffffffff810fa205>] pids_cancel.constprop.4+0x5/0x40 ... Call Trace: <IRQ> [<ffffffff810fb02d>] ? pids_free+0x3d/0xa0 [<ffffffff810f8893>] cgroup_free+0x53/0xe0 [<ffffffff8104ed62>] __put_task_struct+0x42/0x130 [<ffffffff81053557>] delayed_put_task_struct+0x77/0x130 [<ffffffff810c6b34>] rcu_process_callbacks+0x2f4/0x820 [<ffffffff810c6af3>] ? rcu_process_callbacks+0x2b3/0x820 [<ffffffff81056e54>] __do_softirq+0xd4/0x460 [<ffffffff81057369>] irq_exit+0x89/0xa0 [<ffffffff81876212>] smp_apic_timer_interrupt+0x42/0x50 [<ffffffff818747f4>] apic_timer_interrupt+0x84/0x90 <EOI> ... Code: 5b 5d c3 48 89 df 48 c7 c2 c9 f9 ae 81 48 c7 c6 91 2c ae 81 e8 1d 94 0e 00 31 c0 5b 5d c3 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 <f0> 48 83 87 e0 00 00 00 ff 78 01 c3 80 3d 08 7a c1 00 00 74 02 RIP [<ffffffff810fa205>] pids_cancel.constprop.4+0x5/0x40 RSP <ffff88001fc03e20> ---[ end trace 89a4a4b916b90c49 ]--- Kernel panic - not syncing: Fatal exception in interrupt Kernel Offset: disabled ---[ end Kernel panic - not syncing: Fatal exception in interrupt Fix it by making css_set pin the associate css's until its release. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dave Jones <davej@codemonkey.org.uk> Reported-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Link: http://lkml.kernel.org/g/20151120041836.GA18390@codemonkey.org.uk Link: http://lkml.kernel.org/g/5652D448.3080002@bmw-carit.de Fixes: afcf6c8b7544 ("cgroup: add cgroup_subsys->free() method and use it to fix pids controller")
2015-11-23 22:55:41 +03:00
&css->cgroup->e_csets[ssid]);
css_get(css);
}
spin_unlock_bh(&css_set_lock);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
return cset;
}
static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
{
struct cgroup *root_cgrp = kf_root->kn->priv;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
return root_cgrp->root;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
}
static int cgroup_init_root_id(struct cgroup_root *root)
{
int id;
lockdep_assert_held(&cgroup_mutex);
id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL);
if (id < 0)
return id;
root->hierarchy_id = id;
return 0;
}
static void cgroup_exit_root_id(struct cgroup_root *root)
{
lockdep_assert_held(&cgroup_mutex);
if (root->hierarchy_id) {
idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
root->hierarchy_id = 0;
}
}
static void cgroup_free_root(struct cgroup_root *root)
{
if (root) {
/* hierarchy ID should already have been released */
WARN_ON_ONCE(root->hierarchy_id);
idr_destroy(&root->cgroup_idr);
kfree(root);
}
}
static void cgroup_destroy_root(struct cgroup_root *root)
{
struct cgroup *cgrp = &root->cgrp;
struct cgrp_cset_link *link, *tmp_link;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
mutex_lock(&cgroup_mutex);
BUG_ON(atomic_read(&root->nr_cgrps));
BUG_ON(!list_empty(&cgrp->self.children));
/* Rebind all subsystems back to the default hierarchy */
rebind_subsystems(&cgrp_dfl_root, root->subsys_mask);
/*
* Release all the links from cset_links to this hierarchy's
* root cgroup
*/
spin_lock_bh(&css_set_lock);
list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
list_del(&link->cset_link);
list_del(&link->cgrp_link);
kfree(link);
}
spin_unlock_bh(&css_set_lock);
if (!list_empty(&root->root_list)) {
list_del(&root->root_list);
cgroup_root_count--;
}
cgroup_exit_root_id(root);
mutex_unlock(&cgroup_mutex);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
kernfs_destroy_root(root->kf_root);
cgroup_free_root(root);
}
/* look up cgroup associated with given css_set on the specified hierarchy */
static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
struct cgroup_root *root)
{
struct cgroup *res = NULL;
2014-02-13 15:58:40 +04:00
lockdep_assert_held(&cgroup_mutex);
lockdep_assert_held(&css_set_lock);
2014-02-13 15:58:40 +04:00
if (cset == &init_css_set) {
res = &root->cgrp;
} else {
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
struct cgrp_cset_link *link;
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
struct cgroup *c = link->cgrp;
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
if (c->root == root) {
res = c;
break;
}
}
}
2014-02-13 15:58:40 +04:00
BUG_ON(!res);
return res;
}
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/*
* Return the cgroup for "task" from the given hierarchy. Must be
* called with cgroup_mutex and css_set_lock held.
*/
static struct cgroup *task_cgroup_from_root(struct task_struct *task,
struct cgroup_root *root)
{
/*
* No need to lock the task - since we hold cgroup_mutex the
* task can't change groups, so the only thing that can happen
* is that it exits and its css is set back to init_css_set.
*/
return cset_cgroup_from_root(task_css_set(task), root);
}
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/*
* A task must hold cgroup_mutex to modify cgroups.
*
* Any task can increment and decrement the count field without lock.
* So in general, code holding cgroup_mutex can't rely on the count
* field not changing. However, if the count goes to zero, then only
* cgroup_attach_task() can increment it again. Because a count of zero
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
* means that no tasks are currently attached, therefore there is no
* way a task attached to that cgroup can fork (the other way to
* increment the count). So code holding cgroup_mutex can safely
* assume that if the count is zero, it will stay zero. Similarly, if
* a task holds cgroup_mutex on a cgroup with zero count, it
* knows that the cgroup won't be removed, as cgroup_rmdir()
* needs that mutex.
*
* A cgroup can only be deleted if both its 'count' of using tasks
* is zero, and its list of 'children' cgroups is empty. Since all
* tasks in the system use _some_ cgroup, and since there is always at
* least one task in the system (init, pid == 1), therefore, root cgroup
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
* always has either children cgroups and/or using tasks. So we don't
* need a special hack to ensure that root cgroup cannot be deleted.
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
*
* P.S. One more locking exception. RCU is used to guard the
* update of a tasks cgroup pointer by cgroup_attach_task()
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
*/
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
static const struct file_operations proc_cgroupstats_operations;
static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
char *buf)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
struct cgroup_subsys *ss = cft->ss;
if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
!(cgrp->root->flags & CGRP_ROOT_NOPREFIX))
snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s",
cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name,
cft->name);
else
strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
return buf;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
/**
* cgroup_file_mode - deduce file mode of a control file
* @cft: the control file in question
*
* S_IRUGO for read, S_IWUSR for write.
*/
static umode_t cgroup_file_mode(const struct cftype *cft)
{
umode_t mode = 0;
if (cft->read_u64 || cft->read_s64 || cft->seq_show)
mode |= S_IRUGO;
if (cft->write_u64 || cft->write_s64 || cft->write) {
if (cft->flags & CFTYPE_WORLD_WRITABLE)
mode |= S_IWUGO;
else
mode |= S_IWUSR;
}
return mode;
}
cgroup: implement cgroup_subsys->depends_on Currently, the blkio subsystem attributes all of writeback IOs to the root. One of the issues is that there's no way to tell who originated a writeback IO from block layer. Those IOs are usually issued asynchronously from a task which didn't have anything to do with actually generating the dirty pages. The memory subsystem, when enabled, already keeps track of the ownership of each dirty page and it's desirable for blkio to piggyback instead of adding its own per-page tag. blkio piggybacking on memory is an implementation detail which preferably should be handled automatically without requiring explicit userland action. To achieve that, this patch implements cgroup_subsys->depends_on which contains the mask of subsystems which should be enabled together when the subsystem is enabled. The previous patches already implemented the support for enabled but invisible subsystems and cgroup_subsys->depends_on can be easily implemented by updating cgroup_refresh_child_subsys_mask() so that it calculates cgroup->child_subsys_mask considering cgroup_subsys->depends_on of the explicitly enabled subsystems. Documentation/cgroups/unified-hierarchy.txt is updated to explain that subsystems may not become immediately available after being unused from userland and that dependency could be a factor in it. As subsystems may already keep residual references, this doesn't significantly change how subsystem rebinding can be used. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09 02:02:57 +04:00
/**
* cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask
cgroup: implement cgroup_subsys->depends_on Currently, the blkio subsystem attributes all of writeback IOs to the root. One of the issues is that there's no way to tell who originated a writeback IO from block layer. Those IOs are usually issued asynchronously from a task which didn't have anything to do with actually generating the dirty pages. The memory subsystem, when enabled, already keeps track of the ownership of each dirty page and it's desirable for blkio to piggyback instead of adding its own per-page tag. blkio piggybacking on memory is an implementation detail which preferably should be handled automatically without requiring explicit userland action. To achieve that, this patch implements cgroup_subsys->depends_on which contains the mask of subsystems which should be enabled together when the subsystem is enabled. The previous patches already implemented the support for enabled but invisible subsystems and cgroup_subsys->depends_on can be easily implemented by updating cgroup_refresh_child_subsys_mask() so that it calculates cgroup->child_subsys_mask considering cgroup_subsys->depends_on of the explicitly enabled subsystems. Documentation/cgroups/unified-hierarchy.txt is updated to explain that subsystems may not become immediately available after being unused from userland and that dependency could be a factor in it. As subsystems may already keep residual references, this doesn't significantly change how subsystem rebinding can be used. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09 02:02:57 +04:00
* @cgrp: the target cgroup
* @subtree_control: the new subtree_control mask to consider
cgroup: implement cgroup_subsys->depends_on Currently, the blkio subsystem attributes all of writeback IOs to the root. One of the issues is that there's no way to tell who originated a writeback IO from block layer. Those IOs are usually issued asynchronously from a task which didn't have anything to do with actually generating the dirty pages. The memory subsystem, when enabled, already keeps track of the ownership of each dirty page and it's desirable for blkio to piggyback instead of adding its own per-page tag. blkio piggybacking on memory is an implementation detail which preferably should be handled automatically without requiring explicit userland action. To achieve that, this patch implements cgroup_subsys->depends_on which contains the mask of subsystems which should be enabled together when the subsystem is enabled. The previous patches already implemented the support for enabled but invisible subsystems and cgroup_subsys->depends_on can be easily implemented by updating cgroup_refresh_child_subsys_mask() so that it calculates cgroup->child_subsys_mask considering cgroup_subsys->depends_on of the explicitly enabled subsystems. Documentation/cgroups/unified-hierarchy.txt is updated to explain that subsystems may not become immediately available after being unused from userland and that dependency could be a factor in it. As subsystems may already keep residual references, this doesn't significantly change how subsystem rebinding can be used. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09 02:02:57 +04:00
*
* On the default hierarchy, a subsystem may request other subsystems to be
* enabled together through its ->depends_on mask. In such cases, more
* subsystems than specified in "cgroup.subtree_control" may be enabled.
*
* This function calculates which subsystems need to be enabled if
* @subtree_control is to be applied to @cgrp. The returned mask is always
* a superset of @subtree_control and follows the usual hierarchy rules.
cgroup: implement cgroup_subsys->depends_on Currently, the blkio subsystem attributes all of writeback IOs to the root. One of the issues is that there's no way to tell who originated a writeback IO from block layer. Those IOs are usually issued asynchronously from a task which didn't have anything to do with actually generating the dirty pages. The memory subsystem, when enabled, already keeps track of the ownership of each dirty page and it's desirable for blkio to piggyback instead of adding its own per-page tag. blkio piggybacking on memory is an implementation detail which preferably should be handled automatically without requiring explicit userland action. To achieve that, this patch implements cgroup_subsys->depends_on which contains the mask of subsystems which should be enabled together when the subsystem is enabled. The previous patches already implemented the support for enabled but invisible subsystems and cgroup_subsys->depends_on can be easily implemented by updating cgroup_refresh_child_subsys_mask() so that it calculates cgroup->child_subsys_mask considering cgroup_subsys->depends_on of the explicitly enabled subsystems. Documentation/cgroups/unified-hierarchy.txt is updated to explain that subsystems may not become immediately available after being unused from userland and that dependency could be a factor in it. As subsystems may already keep residual references, this doesn't significantly change how subsystem rebinding can be used. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09 02:02:57 +04:00
*/
static u16 cgroup_calc_subtree_ss_mask(struct cgroup *cgrp, u16 subtree_control)
{
cgroup: implement cgroup_subsys->depends_on Currently, the blkio subsystem attributes all of writeback IOs to the root. One of the issues is that there's no way to tell who originated a writeback IO from block layer. Those IOs are usually issued asynchronously from a task which didn't have anything to do with actually generating the dirty pages. The memory subsystem, when enabled, already keeps track of the ownership of each dirty page and it's desirable for blkio to piggyback instead of adding its own per-page tag. blkio piggybacking on memory is an implementation detail which preferably should be handled automatically without requiring explicit userland action. To achieve that, this patch implements cgroup_subsys->depends_on which contains the mask of subsystems which should be enabled together when the subsystem is enabled. The previous patches already implemented the support for enabled but invisible subsystems and cgroup_subsys->depends_on can be easily implemented by updating cgroup_refresh_child_subsys_mask() so that it calculates cgroup->child_subsys_mask considering cgroup_subsys->depends_on of the explicitly enabled subsystems. Documentation/cgroups/unified-hierarchy.txt is updated to explain that subsystems may not become immediately available after being unused from userland and that dependency could be a factor in it. As subsystems may already keep residual references, this doesn't significantly change how subsystem rebinding can be used. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09 02:02:57 +04:00
struct cgroup *parent = cgroup_parent(cgrp);
u16 cur_ss_mask = subtree_control;
cgroup: implement cgroup_subsys->depends_on Currently, the blkio subsystem attributes all of writeback IOs to the root. One of the issues is that there's no way to tell who originated a writeback IO from block layer. Those IOs are usually issued asynchronously from a task which didn't have anything to do with actually generating the dirty pages. The memory subsystem, when enabled, already keeps track of the ownership of each dirty page and it's desirable for blkio to piggyback instead of adding its own per-page tag. blkio piggybacking on memory is an implementation detail which preferably should be handled automatically without requiring explicit userland action. To achieve that, this patch implements cgroup_subsys->depends_on which contains the mask of subsystems which should be enabled together when the subsystem is enabled. The previous patches already implemented the support for enabled but invisible subsystems and cgroup_subsys->depends_on can be easily implemented by updating cgroup_refresh_child_subsys_mask() so that it calculates cgroup->child_subsys_mask considering cgroup_subsys->depends_on of the explicitly enabled subsystems. Documentation/cgroups/unified-hierarchy.txt is updated to explain that subsystems may not become immediately available after being unused from userland and that dependency could be a factor in it. As subsystems may already keep residual references, this doesn't significantly change how subsystem rebinding can be used. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09 02:02:57 +04:00
struct cgroup_subsys *ss;
int ssid;
lockdep_assert_held(&cgroup_mutex);
if (!cgroup_on_dfl(cgrp))
return cur_ss_mask;
cgroup: implement cgroup_subsys->depends_on Currently, the blkio subsystem attributes all of writeback IOs to the root. One of the issues is that there's no way to tell who originated a writeback IO from block layer. Those IOs are usually issued asynchronously from a task which didn't have anything to do with actually generating the dirty pages. The memory subsystem, when enabled, already keeps track of the ownership of each dirty page and it's desirable for blkio to piggyback instead of adding its own per-page tag. blkio piggybacking on memory is an implementation detail which preferably should be handled automatically without requiring explicit userland action. To achieve that, this patch implements cgroup_subsys->depends_on which contains the mask of subsystems which should be enabled together when the subsystem is enabled. The previous patches already implemented the support for enabled but invisible subsystems and cgroup_subsys->depends_on can be easily implemented by updating cgroup_refresh_child_subsys_mask() so that it calculates cgroup->child_subsys_mask considering cgroup_subsys->depends_on of the explicitly enabled subsystems. Documentation/cgroups/unified-hierarchy.txt is updated to explain that subsystems may not become immediately available after being unused from userland and that dependency could be a factor in it. As subsystems may already keep residual references, this doesn't significantly change how subsystem rebinding can be used. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09 02:02:57 +04:00
while (true) {
u16 new_ss_mask = cur_ss_mask;
cgroup: implement cgroup_subsys->depends_on Currently, the blkio subsystem attributes all of writeback IOs to the root. One of the issues is that there's no way to tell who originated a writeback IO from block layer. Those IOs are usually issued asynchronously from a task which didn't have anything to do with actually generating the dirty pages. The memory subsystem, when enabled, already keeps track of the ownership of each dirty page and it's desirable for blkio to piggyback instead of adding its own per-page tag. blkio piggybacking on memory is an implementation detail which preferably should be handled automatically without requiring explicit userland action. To achieve that, this patch implements cgroup_subsys->depends_on which contains the mask of subsystems which should be enabled together when the subsystem is enabled. The previous patches already implemented the support for enabled but invisible subsystems and cgroup_subsys->depends_on can be easily implemented by updating cgroup_refresh_child_subsys_mask() so that it calculates cgroup->child_subsys_mask considering cgroup_subsys->depends_on of the explicitly enabled subsystems. Documentation/cgroups/unified-hierarchy.txt is updated to explain that subsystems may not become immediately available after being unused from userland and that dependency could be a factor in it. As subsystems may already keep residual references, this doesn't significantly change how subsystem rebinding can be used. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09 02:02:57 +04:00
do_each_subsys_mask(ss, ssid, cur_ss_mask) {
new_ss_mask |= ss->depends_on;
} while_each_subsys_mask();
cgroup: implement cgroup_subsys->depends_on Currently, the blkio subsystem attributes all of writeback IOs to the root. One of the issues is that there's no way to tell who originated a writeback IO from block layer. Those IOs are usually issued asynchronously from a task which didn't have anything to do with actually generating the dirty pages. The memory subsystem, when enabled, already keeps track of the ownership of each dirty page and it's desirable for blkio to piggyback instead of adding its own per-page tag. blkio piggybacking on memory is an implementation detail which preferably should be handled automatically without requiring explicit userland action. To achieve that, this patch implements cgroup_subsys->depends_on which contains the mask of subsystems which should be enabled together when the subsystem is enabled. The previous patches already implemented the support for enabled but invisible subsystems and cgroup_subsys->depends_on can be easily implemented by updating cgroup_refresh_child_subsys_mask() so that it calculates cgroup->child_subsys_mask considering cgroup_subsys->depends_on of the explicitly enabled subsystems. Documentation/cgroups/unified-hierarchy.txt is updated to explain that subsystems may not become immediately available after being unused from userland and that dependency could be a factor in it. As subsystems may already keep residual references, this doesn't significantly change how subsystem rebinding can be used. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09 02:02:57 +04:00
/*
* Mask out subsystems which aren't available. This can
* happen only if some depended-upon subsystems were bound
* to non-default hierarchies.
*/
if (parent)
new_ss_mask &= parent->subtree_ss_mask;
cgroup: implement cgroup_subsys->depends_on Currently, the blkio subsystem attributes all of writeback IOs to the root. One of the issues is that there's no way to tell who originated a writeback IO from block layer. Those IOs are usually issued asynchronously from a task which didn't have anything to do with actually generating the dirty pages. The memory subsystem, when enabled, already keeps track of the ownership of each dirty page and it's desirable for blkio to piggyback instead of adding its own per-page tag. blkio piggybacking on memory is an implementation detail which preferably should be handled automatically without requiring explicit userland action. To achieve that, this patch implements cgroup_subsys->depends_on which contains the mask of subsystems which should be enabled together when the subsystem is enabled. The previous patches already implemented the support for enabled but invisible subsystems and cgroup_subsys->depends_on can be easily implemented by updating cgroup_refresh_child_subsys_mask() so that it calculates cgroup->child_subsys_mask considering cgroup_subsys->depends_on of the explicitly enabled subsystems. Documentation/cgroups/unified-hierarchy.txt is updated to explain that subsystems may not become immediately available after being unused from userland and that dependency could be a factor in it. As subsystems may already keep residual references, this doesn't significantly change how subsystem rebinding can be used. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
2014-07-09 02:02:57 +04:00
else
new_ss_mask &= cgrp->root->subsys_mask;
if (new_ss_mask == cur_ss_mask)
break;
cur_ss_mask = new_ss_mask;
}
return cur_ss_mask;
}
/**
* cgroup_refresh_subtree_ss_mask - update subtree_ss_mask
* @cgrp: the target cgroup
*
* Update @cgrp->subtree_ss_mask according to the current
* @cgrp->subtree_control using cgroup_calc_subtree_ss_mask().
*/
static void cgroup_refresh_subtree_ss_mask(struct cgroup *cgrp)
{
cgrp->subtree_ss_mask =
cgroup_calc_subtree_ss_mask(cgrp, cgrp->subtree_control);
}
/**
* cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
* @kn: the kernfs_node being serviced
*
* This helper undoes cgroup_kn_lock_live() and should be invoked before
* the method finishes if locking succeeded. Note that once this function
* returns the cgroup returned by cgroup_kn_lock_live() may become
* inaccessible any time. If the caller intends to continue to access the
* cgroup, it should pin it before invoking this function.
*/
static void cgroup_kn_unlock(struct kernfs_node *kn)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
struct cgroup *cgrp;
if (kernfs_type(kn) == KERNFS_DIR)
cgrp = kn->priv;
else
cgrp = kn->parent->priv;
mutex_unlock(&cgroup_mutex);
kernfs_unbreak_active_protection(kn);
cgroup_put(cgrp);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
/**
* cgroup_kn_lock_live - locking helper for cgroup kernfs methods
* @kn: the kernfs_node being serviced
*
* This helper is to be used by a cgroup kernfs method currently servicing
* @kn. It breaks the active protection, performs cgroup locking and
* verifies that the associated cgroup is alive. Returns the cgroup if
* alive; otherwise, %NULL. A successful return should be undone by a
* matching cgroup_kn_unlock() invocation.
*
* Any cgroup kernfs method implementation which requires locking the
* associated cgroup should use this helper. It avoids nesting cgroup
* locking under kernfs active protection and allows all kernfs operations
* including self-removal.
*/
static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn)
{
struct cgroup *cgrp;
if (kernfs_type(kn) == KERNFS_DIR)
cgrp = kn->priv;
else
cgrp = kn->parent->priv;
/*
* We're gonna grab cgroup_mutex which nests outside kernfs
* active_ref. cgroup liveliness check alone provides enough
* protection against removal. Ensure @cgrp stays accessible and
* break the active_ref protection.
*/
if (!cgroup_tryget(cgrp))
return NULL;
kernfs_break_active_protection(kn);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
mutex_lock(&cgroup_mutex);
if (!cgroup_is_dead(cgrp))
return cgrp;
cgroup_kn_unlock(kn);
return NULL;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
{
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
char name[CGROUP_FILE_NAME_MAX];
lockdep_assert_held(&cgroup_mutex);
if (cft->file_offset) {
struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss);
struct cgroup_file *cfile = (void *)css + cft->file_offset;
spin_lock_irq(&cgroup_file_kn_lock);
cfile->kn = NULL;
spin_unlock_irq(&cgroup_file_kn_lock);
}
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
}
/**
* css_clear_dir - remove subsys files in a cgroup directory
* @css: taget css
* @cgrp_override: specify if target cgroup is different from css->cgroup
*/
static void css_clear_dir(struct cgroup_subsys_state *css,
struct cgroup *cgrp_override)
{
struct cgroup *cgrp = cgrp_override ?: css->cgroup;
struct cftype *cfts;
if (!(css->flags & CSS_VISIBLE))
return;
css->flags &= ~CSS_VISIBLE;
list_for_each_entry(cfts, &css->ss->cfts, node)
cgroup_addrm_files(css, cgrp, cfts, false);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
/**
* css_populate_dir - create subsys files in a cgroup directory
* @css: target css
* @cgrp_overried: specify if target cgroup is different from css->cgroup
*
* On failure, no file is added.
*/
static int css_populate_dir(struct cgroup_subsys_state *css,
struct cgroup *cgrp_override)
{
struct cgroup *cgrp = cgrp_override ?: css->cgroup;
struct cftype *cfts, *failed_cfts;
int ret;
if (css->flags & CSS_VISIBLE)
return 0;
if (!css->ss) {
if (cgroup_on_dfl(cgrp))
cfts = cgroup_dfl_base_files;
else
cfts = cgroup_legacy_base_files;
return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true);
}
list_for_each_entry(cfts, &css->ss->cfts, node) {
ret = cgroup_addrm_files(css, cgrp, cfts, true);
if (ret < 0) {
failed_cfts = cfts;
goto err;
}
}
css->flags |= CSS_VISIBLE;
return 0;
err:
list_for_each_entry(cfts, &css->ss->cfts, node) {
if (cfts == failed_cfts)
break;
cgroup_addrm_files(css, cgrp, cfts, false);
}
return ret;
}
static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
struct cgroup *dcgrp = &dst_root->cgrp;
struct cgroup_subsys *ss;
u16 tmp_ss_mask;
int ssid, i, ret;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
cgroup: introduce cgroup_tree_mutex Currently cgroup uses combination of inode->i_mutex'es and cgroup_mutex for synchronization. With the scheduled kernfs conversion, i_mutex'es will be removed. Unfortunately, just using cgroup_mutex isn't possible. All kernfs file and syscall operations, most of which require grabbing cgroup_mutex, will be called with kernfs active ref held and, if we try to perform kernfs removals under cgroup_mutex, it can deadlock as kernfs_remove() tries to drain the target node. Let's introduce a new outer mutex, cgroup_tree_mutex, which protects stuff used during hierarchy changing operations - cftypes and all the operations which may affect the cgroupfs. It also covers css association and iteration. This allows cgroup_css(), for_each_css() and other css iterators to be called under cgroup_tree_mutex. The new mutex will nest above both kernfs's active ref protection and cgroup_mutex. By protecting tree modifications with a separate outer mutex, we can get rid of the forementioned deadlock condition. Actual file additions and removals now require cgroup_tree_mutex instead of cgroup_mutex. Currently, cgroup_tree_mutex is never used without cgroup_mutex; however, we'll soon add hierarchy modification sections which are only protected by cgroup_tree_mutex. In the future, we might want to make the locking more granular by better splitting the coverages of the two mutexes. For now, this should do. v2: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-11 20:52:47 +04:00
lockdep_assert_held(&cgroup_mutex);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
do_each_subsys_mask(ss, ssid, ss_mask) {
/* if @ss has non-root csses attached to it, can't move */
if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss)))
return -EBUSY;
cgroup: treat cgroup_dummy_root as an equivalent hierarchy during rebinding Currently, while rebinding, cgroup_dummy_root serves as the anchor point. In addition to the target root, rebind_subsystems() takes @added_mask and @removed_mask. The subsystems specified in the former are expected to be on the dummy root and then moved to the target root. The ones in the latter are moved from non-dummy root to dummy. Now that the dummy root is a fully functional one and we're planning to use it for the default unified hierarchy, this level of distinction between dummy and non-dummy roots is quite awkward. This patch updates rebind_subsystems() to take the target root and one subsystem mask and move the specified subsystmes to the target root which may or may not be the dummy root. IOW, unbinding now becomes moving the subsystems to the dummy root and binding to non-dummy root. This makes the dummy root mostly equivalent to other hierarchies in terms of the mechanism of moving subsystems around; however, we still retain all the semantical restrictions so that this patch doesn't introduce any visible behavior differences. Another noteworthy detail is that rebind_subsystems() guarantees that moving a subsystem to the dummy root never fails so that valid unmounting attempts always succeed. This unifies binding and unbinding of subsystems. The invocation points of ->bind() were inconsistent between the two and now moved after whole rebinding is complete. This doesn't break the current users and generally makes more sense. All rebind_subsystems() users are converted accordingly. Note that cgroup_remount() now makes two calls to rebind_subsystems() to bind and then unbind the requested subsystems. This will allow repurposing of the dummy hierarchy as the default unified hierarchy and shouldn't make any userland visible behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-03-19 18:23:54 +04:00
/* can't move between two non-dummy roots either */
if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root)
cgroup: treat cgroup_dummy_root as an equivalent hierarchy during rebinding Currently, while rebinding, cgroup_dummy_root serves as the anchor point. In addition to the target root, rebind_subsystems() takes @added_mask and @removed_mask. The subsystems specified in the former are expected to be on the dummy root and then moved to the target root. The ones in the latter are moved from non-dummy root to dummy. Now that the dummy root is a fully functional one and we're planning to use it for the default unified hierarchy, this level of distinction between dummy and non-dummy roots is quite awkward. This patch updates rebind_subsystems() to take the target root and one subsystem mask and move the specified subsystmes to the target root which may or may not be the dummy root. IOW, unbinding now becomes moving the subsystems to the dummy root and binding to non-dummy root. This makes the dummy root mostly equivalent to other hierarchies in terms of the mechanism of moving subsystems around; however, we still retain all the semantical restrictions so that this patch doesn't introduce any visible behavior differences. Another noteworthy detail is that rebind_subsystems() guarantees that moving a subsystem to the dummy root never fails so that valid unmounting attempts always succeed. This unifies binding and unbinding of subsystems. The invocation points of ->bind() were inconsistent between the two and now moved after whole rebinding is complete. This doesn't break the current users and generally makes more sense. All rebind_subsystems() users are converted accordingly. Note that cgroup_remount() now makes two calls to rebind_subsystems() to bind and then unbind the requested subsystems. This will allow repurposing of the dummy hierarchy as the default unified hierarchy and shouldn't make any userland visible behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-03-19 18:23:54 +04:00
return -EBUSY;
} while_each_subsys_mask();
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* skip creating root files on dfl_root for inhibited subsystems */
tmp_ss_mask = ss_mask;
if (dst_root == &cgrp_dfl_root)
tmp_ss_mask &= ~cgrp_dfl_inhibit_ss_mask;
do_each_subsys_mask(ss, ssid, tmp_ss_mask) {
struct cgroup *scgrp = &ss->root->cgrp;
int tssid;
ret = css_populate_dir(cgroup_css(scgrp, ss), dcgrp);
if (!ret)
continue;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
2014-03-19 18:23:55 +04:00
/*
* Rebinding back to the default root is not allowed to
* fail. Using both default and non-default roots should
* be rare. Moving subsystems back and forth even more so.
* Just warn about it and continue.
*/
if (dst_root == &cgrp_dfl_root) {
if (cgrp_dfl_visible) {
pr_warn("failed to create files (%d) while rebinding 0x%x to default root\n",
ret, ss_mask);
pr_warn("you may retry by moving them to a different hierarchy and unbinding\n");
}
continue;
2014-03-19 18:23:55 +04:00
}
do_each_subsys_mask(ss, tssid, tmp_ss_mask) {
if (tssid == ssid)
break;
css_clear_dir(cgroup_css(scgrp, ss), dcgrp);
} while_each_subsys_mask();
return ret;
} while_each_subsys_mask();
cgroup: make rebind_subsystems() handle file additions and removals with proper error handling Currently, creating and removing cgroup files in the root directory are handled separately from the actual subsystem binding and unbinding which happens in rebind_subsystems(). Also, rebind_subsystems() users aren't handling file creation errors properly. Let's integrate top_cgroup file handling into rebind_subsystems() so that it's simpler to use and everyone handles file creation errors correctly. * On a successful return, rebind_subsystems() is guaranteed to have created all files of the new subsystems and deleted the ones belonging to the removed subsystems. After a failure, no file is created or removed. * cgroup_remount() no longer needs to make explicit populate/clear calls as it's all handled by rebind_subsystems(), and it gets proper error handling automatically. * cgroup_mount() has been updated such that the root dentry and cgroup are linked before rebind_subsystems(). Also, the init_cred dancing and base file handling are moved right above rebind_subsystems() call and proper error handling for the base files is added. While at it, add a comment explaining what's going on with the cred thing. * cgroup_kill_sb() calls rebind_subsystems() to unbind all subsystems which now implies removing all subsystem files which requires the directory's i_mutex. Grab it. This means that files on the root cgroup are removed earlier - they used to be deleted from generic super_block cleanup from vfs. This doesn't lead to any functional difference and it's cleaner to do the clean up explicitly for all files. Combined with the previous changes, this makes all cgroup file creation errors handled correctly. v2: Added comment on init_cred. v3: Li spotted that cgroup_mount() wasn't freeing tmp_links after base file addition failure. Fix it by adding free_tmp_links error handling label. v4: v3 introduced build bugs which got noticed by Fengguang's awesome kbuild test robot. Fixed, and shame on me. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com>
2013-06-29 04:07:30 +04:00
/*
* Nothing can fail from this point on. Remove files for the
* removed subsystems and rebind each subsystem.
*/
do_each_subsys_mask(ss, ssid, ss_mask) {
struct cgroup_root *src_root = ss->root;
struct cgroup *scgrp = &src_root->cgrp;
struct cgroup_subsys_state *css = cgroup_css(scgrp, ss);
struct css_set *cset;
WARN_ON(!css || cgroup_css(dcgrp, ss));
css_clear_dir(css, NULL);
RCU_INIT_POINTER(scgrp->subsys[ssid], NULL);
rcu_assign_pointer(dcgrp->subsys[ssid], css);
cgroup: treat cgroup_dummy_root as an equivalent hierarchy during rebinding Currently, while rebinding, cgroup_dummy_root serves as the anchor point. In addition to the target root, rebind_subsystems() takes @added_mask and @removed_mask. The subsystems specified in the former are expected to be on the dummy root and then moved to the target root. The ones in the latter are moved from non-dummy root to dummy. Now that the dummy root is a fully functional one and we're planning to use it for the default unified hierarchy, this level of distinction between dummy and non-dummy roots is quite awkward. This patch updates rebind_subsystems() to take the target root and one subsystem mask and move the specified subsystmes to the target root which may or may not be the dummy root. IOW, unbinding now becomes moving the subsystems to the dummy root and binding to non-dummy root. This makes the dummy root mostly equivalent to other hierarchies in terms of the mechanism of moving subsystems around; however, we still retain all the semantical restrictions so that this patch doesn't introduce any visible behavior differences. Another noteworthy detail is that rebind_subsystems() guarantees that moving a subsystem to the dummy root never fails so that valid unmounting attempts always succeed. This unifies binding and unbinding of subsystems. The invocation points of ->bind() were inconsistent between the two and now moved after whole rebinding is complete. This doesn't break the current users and generally makes more sense. All rebind_subsystems() users are converted accordingly. Note that cgroup_remount() now makes two calls to rebind_subsystems() to bind and then unbind the requested subsystems. This will allow repurposing of the dummy hierarchy as the default unified hierarchy and shouldn't make any userland visible behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-03-19 18:23:54 +04:00
ss->root = dst_root;
css->cgroup = dcgrp;
spin_lock_bh(&css_set_lock);
hash_for_each(css_set_table, i, cset, hlist)
list_move_tail(&cset->e_cset_node[ss->id],
&dcgrp->e_csets[ss->id]);
spin_unlock_bh(&css_set_lock);
src_root->subsys_mask &= ~(1 << ssid);
scgrp->subtree_control &= ~(1 << ssid);
cgroup_refresh_subtree_ss_mask(scgrp);
/* default hierarchy doesn't enable controllers by default */
dst_root->subsys_mask |= 1 << ssid;
if (dst_root == &cgrp_dfl_root) {
static_branch_enable(cgroup_subsys_on_dfl_key[ssid]);
} else {
dcgrp->subtree_control |= 1 << ssid;
cgroup_refresh_subtree_ss_mask(dcgrp);
static_branch_disable(cgroup_subsys_on_dfl_key[ssid]);
}
cgroup: treat cgroup_dummy_root as an equivalent hierarchy during rebinding Currently, while rebinding, cgroup_dummy_root serves as the anchor point. In addition to the target root, rebind_subsystems() takes @added_mask and @removed_mask. The subsystems specified in the former are expected to be on the dummy root and then moved to the target root. The ones in the latter are moved from non-dummy root to dummy. Now that the dummy root is a fully functional one and we're planning to use it for the default unified hierarchy, this level of distinction between dummy and non-dummy roots is quite awkward. This patch updates rebind_subsystems() to take the target root and one subsystem mask and move the specified subsystmes to the target root which may or may not be the dummy root. IOW, unbinding now becomes moving the subsystems to the dummy root and binding to non-dummy root. This makes the dummy root mostly equivalent to other hierarchies in terms of the mechanism of moving subsystems around; however, we still retain all the semantical restrictions so that this patch doesn't introduce any visible behavior differences. Another noteworthy detail is that rebind_subsystems() guarantees that moving a subsystem to the dummy root never fails so that valid unmounting attempts always succeed. This unifies binding and unbinding of subsystems. The invocation points of ->bind() were inconsistent between the two and now moved after whole rebinding is complete. This doesn't break the current users and generally makes more sense. All rebind_subsystems() users are converted accordingly. Note that cgroup_remount() now makes two calls to rebind_subsystems() to bind and then unbind the requested subsystems. This will allow repurposing of the dummy hierarchy as the default unified hierarchy and shouldn't make any userland visible behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-03-19 18:23:54 +04:00
if (ss->bind)
ss->bind(css);
} while_each_subsys_mask();
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
kernfs_activate(dcgrp->kn);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
return 0;
}
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
static int cgroup_show_options(struct seq_file *seq,
struct kernfs_root *kf_root)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
struct cgroup_subsys *ss;
int ssid;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
if (root != &cgrp_dfl_root)
for_each_subsys(ss, ssid)
if (root->subsys_mask & (1 << ssid))
seq_show_option(seq, ss->legacy_name, NULL);
if (root->flags & CGRP_ROOT_NOPREFIX)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
seq_puts(seq, ",noprefix");
if (root->flags & CGRP_ROOT_XATTR)
cgroup: add xattr support This is one of the items in the plumber's wish list. For use cases: >> What would the use case be for this? > > Attaching meta information to services, in an easily discoverable > way. For example, in systemd we create one cgroup for each service, and > could then store data like the main pid of the specific service as an > xattr on the cgroup itself. That way we'd have almost all service state > in the cgroupfs, which would make it possible to terminate systemd and > later restart it without losing any state information. But there's more: > for example, some very peculiar services cannot be terminated on > shutdown (i.e. fakeraid DM stuff) and it would be really nice if the > services in question could just mark that on their cgroup, by setting an > xattr. On the more desktopy side of things there are other > possibilities: for example there are plans defining what an application > is along the lines of a cgroup (i.e. an app being a collection of > processes). With xattrs one could then attach an icon or human readable > program name on the cgroup. > > The key idea is that this would allow attaching runtime meta information > to cgroups and everything they model (services, apps, vms), that doesn't > need any complex userspace infrastructure, has good access control > (i.e. because the file system enforces that anyway, and there's the > "trusted." xattr namespace), notifications (inotify), and can easily be > shared among applications. > > Lennart v7: - no changes v6: - remove user xattr namespace, only allow trusted and security v5: - check for capabilities before setting/removing xattrs v4: - no changes v3: - instead of config option, use mount option to enable xattr support Original-patch-by: Li Zefan <lizefan@huawei.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Lennart Poettering <lpoetter@redhat.com> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Aristeu Rozanski <aris@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-08-24 00:53:30 +04:00
seq_puts(seq, ",xattr");
spin_lock(&release_agent_path_lock);
if (strlen(root->release_agent_path))
fs: create and use seq_show_option for escaping Many file systems that implement the show_options hook fail to correctly escape their output which could lead to unescaped characters (e.g. new lines) leaking into /proc/mounts and /proc/[pid]/mountinfo files. This could lead to confusion, spoofed entries (resulting in things like systemd issuing false d-bus "mount" notifications), and who knows what else. This looks like it would only be the root user stepping on themselves, but it's possible weird things could happen in containers or in other situations with delegated mount privileges. Here's an example using overlay with setuid fusermount trusting the contents of /proc/mounts (via the /etc/mtab symlink). Imagine the use of "sudo" is something more sneaky: $ BASE="ovl" $ MNT="$BASE/mnt" $ LOW="$BASE/lower" $ UP="$BASE/upper" $ WORK="$BASE/work/ 0 0 none /proc fuse.pwn user_id=1000" $ mkdir -p "$LOW" "$UP" "$WORK" $ sudo mount -t overlay -o "lowerdir=$LOW,upperdir=$UP,workdir=$WORK" none /mnt $ cat /proc/mounts none /root/ovl/mnt overlay rw,relatime,lowerdir=ovl/lower,upperdir=ovl/upper,workdir=ovl/work/ 0 0 none /proc fuse.pwn user_id=1000 0 0 $ fusermount -u /proc $ cat /proc/mounts cat: /proc/mounts: No such file or directory This fixes the problem by adding new seq_show_option and seq_show_option_n helpers, and updating the vulnerable show_option handlers to use them as needed. Some, like SELinux, need to be open coded due to unusual existing escape mechanisms. [akpm@linux-foundation.org: add lost chunk, per Kees] [keescook@chromium.org: seq_show_option should be using const parameters] Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Acked-by: Jan Kara <jack@suse.com> Acked-by: Paul Moore <paul@paul-moore.com> Cc: J. R. Okajima <hooanon05g@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-05 01:44:57 +03:00
seq_show_option(seq, "release_agent",
root->release_agent_path);
spin_unlock(&release_agent_path_lock);
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
cgroup: add clone_children control file The ns_cgroup is a control group interacting with the namespaces. When a new namespace is created, a corresponding cgroup is automatically created too. The cgroup name is the pid of the process who did 'unshare' or the child of 'clone'. This cgroup is tied with the namespace because it prevents a process to escape the control group and use the post_clone callback, so the child cgroup inherits the values of the parent cgroup. Unfortunately, the more we use this cgroup and the more we are facing problems with it: (1) when a process unshares, the cgroup name may conflict with a previous cgroup with the same pid, so unshare or clone return -EEXIST (2) the cgroup creation is out of control because there may have an application creating several namespaces where the system will automatically create several cgroups in his back and let them on the cgroupfs (eg. a vrf based on the network namespace). (3) the mix of (1) and (2) force an administrator to regularly check and clean these cgroups. This patchset removes the ns_cgroup by adding a new flag to the cgroup and the cgroupfs mount option. It enables the copy of the parent cgroup when a child cgroup is created. We can then safely remove the ns_cgroup as this flag brings a compatibility. We have now to manually create and add the task to a cgroup, which is consistent with the cgroup framework. This patch: Sent as an answer to a previous thread around the ns_cgroup. https://lists.linux-foundation.org/pipermail/containers/2009-June/018627.html It adds a control file 'clone_children' for a cgroup. This control file is a boolean specifying if the child cgroup should be a clone of the parent cgroup or not. The default value is 'false'. This flag makes the child cgroup to call the post_clone callback of all the subsystem, if it is available. At present, the cpuset is the only one which had implemented the post_clone callback. The option can be set at mount time by specifying the 'clone_children' mount option. Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Paul Menage <menage@google.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:35 +04:00
seq_puts(seq, ",clone_children");
if (strlen(root->name))
fs: create and use seq_show_option for escaping Many file systems that implement the show_options hook fail to correctly escape their output which could lead to unescaped characters (e.g. new lines) leaking into /proc/mounts and /proc/[pid]/mountinfo files. This could lead to confusion, spoofed entries (resulting in things like systemd issuing false d-bus "mount" notifications), and who knows what else. This looks like it would only be the root user stepping on themselves, but it's possible weird things could happen in containers or in other situations with delegated mount privileges. Here's an example using overlay with setuid fusermount trusting the contents of /proc/mounts (via the /etc/mtab symlink). Imagine the use of "sudo" is something more sneaky: $ BASE="ovl" $ MNT="$BASE/mnt" $ LOW="$BASE/lower" $ UP="$BASE/upper" $ WORK="$BASE/work/ 0 0 none /proc fuse.pwn user_id=1000" $ mkdir -p "$LOW" "$UP" "$WORK" $ sudo mount -t overlay -o "lowerdir=$LOW,upperdir=$UP,workdir=$WORK" none /mnt $ cat /proc/mounts none /root/ovl/mnt overlay rw,relatime,lowerdir=ovl/lower,upperdir=ovl/upper,workdir=ovl/work/ 0 0 none /proc fuse.pwn user_id=1000 0 0 $ fusermount -u /proc $ cat /proc/mounts cat: /proc/mounts: No such file or directory This fixes the problem by adding new seq_show_option and seq_show_option_n helpers, and updating the vulnerable show_option handlers to use them as needed. Some, like SELinux, need to be open coded due to unusual existing escape mechanisms. [akpm@linux-foundation.org: add lost chunk, per Kees] [keescook@chromium.org: seq_show_option should be using const parameters] Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Acked-by: Jan Kara <jack@suse.com> Acked-by: Paul Moore <paul@paul-moore.com> Cc: J. R. Okajima <hooanon05g@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-09-05 01:44:57 +03:00
seq_show_option(seq, "name", root->name);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
return 0;
}
struct cgroup_sb_opts {
u16 subsys_mask;
unsigned int flags;
char *release_agent;
bool cpuset_clone_children;
char *name;
/* User explicitly requested empty subsystem */
bool none;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
};
static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
cgroup: make the mount options parsing more accurate Current behavior: ================= (1) When we mount a cgroup, we can specify the 'all' option which means to enable all the cgroup subsystems. This is the default option when no option is specified. (2) If we want to mount a cgroup with a subset of the supported cgroup subsystems, we have to specify a subsystems name list for the mount option. (3) If we specify another option like 'noprefix' or 'release_agent', the actual code wants the 'all' or a subsystem name option specified also. Not critical but a bit not friendly as we should assume (1) in this case. (4) Logically, the 'all' option is mutually exclusive with a subsystem name, but this is not detected. In other words: succeed : mount -t cgroup -o all,freezer cgroup /cgroup => is it 'all' or 'freezer' ? fails : mount -t cgroup -o noprefix cgroup /cgroup => succeed if we do '-o noprefix,all' The following patches consolidate a bit the mount options check. New behavior: ============= (1) untouched (2) untouched (3) the 'all' option will be by default when specifying other than a subsystem name option (4) raises an error In other words: fails : mount -t cgroup -o all,freezer cgroup /cgroup succeed : mount -t cgroup -o noprefix cgroup /cgroup For the sake of lisibility, the if ... then ... else ... if ... indentation when parsing the options has been changed to: if ... then ... continue fi Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:37 +04:00
char *token, *o = data;
bool all_ss = false, one_ss = false;
u16 mask = U16_MAX;
struct cgroup_subsys *ss;
int nr_opts = 0;
int i;
#ifdef CONFIG_CPUSETS
mask = ~((u16)1 << cpuset_cgrp_id);
#endif
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
memset(opts, 0, sizeof(*opts));
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
while ((token = strsep(&o, ",")) != NULL) {
nr_opts++;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
if (!*token)
return -EINVAL;
cgroup: make the mount options parsing more accurate Current behavior: ================= (1) When we mount a cgroup, we can specify the 'all' option which means to enable all the cgroup subsystems. This is the default option when no option is specified. (2) If we want to mount a cgroup with a subset of the supported cgroup subsystems, we have to specify a subsystems name list for the mount option. (3) If we specify another option like 'noprefix' or 'release_agent', the actual code wants the 'all' or a subsystem name option specified also. Not critical but a bit not friendly as we should assume (1) in this case. (4) Logically, the 'all' option is mutually exclusive with a subsystem name, but this is not detected. In other words: succeed : mount -t cgroup -o all,freezer cgroup /cgroup => is it 'all' or 'freezer' ? fails : mount -t cgroup -o noprefix cgroup /cgroup => succeed if we do '-o noprefix,all' The following patches consolidate a bit the mount options check. New behavior: ============= (1) untouched (2) untouched (3) the 'all' option will be by default when specifying other than a subsystem name option (4) raises an error In other words: fails : mount -t cgroup -o all,freezer cgroup /cgroup succeed : mount -t cgroup -o noprefix cgroup /cgroup For the sake of lisibility, the if ... then ... else ... if ... indentation when parsing the options has been changed to: if ... then ... continue fi Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:37 +04:00
if (!strcmp(token, "none")) {
/* Explicitly have no subsystems */
opts->none = true;
cgroup: make the mount options parsing more accurate Current behavior: ================= (1) When we mount a cgroup, we can specify the 'all' option which means to enable all the cgroup subsystems. This is the default option when no option is specified. (2) If we want to mount a cgroup with a subset of the supported cgroup subsystems, we have to specify a subsystems name list for the mount option. (3) If we specify another option like 'noprefix' or 'release_agent', the actual code wants the 'all' or a subsystem name option specified also. Not critical but a bit not friendly as we should assume (1) in this case. (4) Logically, the 'all' option is mutually exclusive with a subsystem name, but this is not detected. In other words: succeed : mount -t cgroup -o all,freezer cgroup /cgroup => is it 'all' or 'freezer' ? fails : mount -t cgroup -o noprefix cgroup /cgroup => succeed if we do '-o noprefix,all' The following patches consolidate a bit the mount options check. New behavior: ============= (1) untouched (2) untouched (3) the 'all' option will be by default when specifying other than a subsystem name option (4) raises an error In other words: fails : mount -t cgroup -o all,freezer cgroup /cgroup succeed : mount -t cgroup -o noprefix cgroup /cgroup For the sake of lisibility, the if ... then ... else ... if ... indentation when parsing the options has been changed to: if ... then ... continue fi Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:37 +04:00
continue;
}
if (!strcmp(token, "all")) {
/* Mutually exclusive option 'all' + subsystem name */
if (one_ss)
return -EINVAL;
all_ss = true;
continue;
}
if (!strcmp(token, "noprefix")) {
opts->flags |= CGRP_ROOT_NOPREFIX;
cgroup: make the mount options parsing more accurate Current behavior: ================= (1) When we mount a cgroup, we can specify the 'all' option which means to enable all the cgroup subsystems. This is the default option when no option is specified. (2) If we want to mount a cgroup with a subset of the supported cgroup subsystems, we have to specify a subsystems name list for the mount option. (3) If we specify another option like 'noprefix' or 'release_agent', the actual code wants the 'all' or a subsystem name option specified also. Not critical but a bit not friendly as we should assume (1) in this case. (4) Logically, the 'all' option is mutually exclusive with a subsystem name, but this is not detected. In other words: succeed : mount -t cgroup -o all,freezer cgroup /cgroup => is it 'all' or 'freezer' ? fails : mount -t cgroup -o noprefix cgroup /cgroup => succeed if we do '-o noprefix,all' The following patches consolidate a bit the mount options check. New behavior: ============= (1) untouched (2) untouched (3) the 'all' option will be by default when specifying other than a subsystem name option (4) raises an error In other words: fails : mount -t cgroup -o all,freezer cgroup /cgroup succeed : mount -t cgroup -o noprefix cgroup /cgroup For the sake of lisibility, the if ... then ... else ... if ... indentation when parsing the options has been changed to: if ... then ... continue fi Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:37 +04:00
continue;
}
if (!strcmp(token, "clone_children")) {
opts->cpuset_clone_children = true;
cgroup: make the mount options parsing more accurate Current behavior: ================= (1) When we mount a cgroup, we can specify the 'all' option which means to enable all the cgroup subsystems. This is the default option when no option is specified. (2) If we want to mount a cgroup with a subset of the supported cgroup subsystems, we have to specify a subsystems name list for the mount option. (3) If we specify another option like 'noprefix' or 'release_agent', the actual code wants the 'all' or a subsystem name option specified also. Not critical but a bit not friendly as we should assume (1) in this case. (4) Logically, the 'all' option is mutually exclusive with a subsystem name, but this is not detected. In other words: succeed : mount -t cgroup -o all,freezer cgroup /cgroup => is it 'all' or 'freezer' ? fails : mount -t cgroup -o noprefix cgroup /cgroup => succeed if we do '-o noprefix,all' The following patches consolidate a bit the mount options check. New behavior: ============= (1) untouched (2) untouched (3) the 'all' option will be by default when specifying other than a subsystem name option (4) raises an error In other words: fails : mount -t cgroup -o all,freezer cgroup /cgroup succeed : mount -t cgroup -o noprefix cgroup /cgroup For the sake of lisibility, the if ... then ... else ... if ... indentation when parsing the options has been changed to: if ... then ... continue fi Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:37 +04:00
continue;
}
cgroup: add xattr support This is one of the items in the plumber's wish list. For use cases: >> What would the use case be for this? > > Attaching meta information to services, in an easily discoverable > way. For example, in systemd we create one cgroup for each service, and > could then store data like the main pid of the specific service as an > xattr on the cgroup itself. That way we'd have almost all service state > in the cgroupfs, which would make it possible to terminate systemd and > later restart it without losing any state information. But there's more: > for example, some very peculiar services cannot be terminated on > shutdown (i.e. fakeraid DM stuff) and it would be really nice if the > services in question could just mark that on their cgroup, by setting an > xattr. On the more desktopy side of things there are other > possibilities: for example there are plans defining what an application > is along the lines of a cgroup (i.e. an app being a collection of > processes). With xattrs one could then attach an icon or human readable > program name on the cgroup. > > The key idea is that this would allow attaching runtime meta information > to cgroups and everything they model (services, apps, vms), that doesn't > need any complex userspace infrastructure, has good access control > (i.e. because the file system enforces that anyway, and there's the > "trusted." xattr namespace), notifications (inotify), and can easily be > shared among applications. > > Lennart v7: - no changes v6: - remove user xattr namespace, only allow trusted and security v5: - check for capabilities before setting/removing xattrs v4: - no changes v3: - instead of config option, use mount option to enable xattr support Original-patch-by: Li Zefan <lizefan@huawei.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Lennart Poettering <lpoetter@redhat.com> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Aristeu Rozanski <aris@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-08-24 00:53:30 +04:00
if (!strcmp(token, "xattr")) {
opts->flags |= CGRP_ROOT_XATTR;
cgroup: add xattr support This is one of the items in the plumber's wish list. For use cases: >> What would the use case be for this? > > Attaching meta information to services, in an easily discoverable > way. For example, in systemd we create one cgroup for each service, and > could then store data like the main pid of the specific service as an > xattr on the cgroup itself. That way we'd have almost all service state > in the cgroupfs, which would make it possible to terminate systemd and > later restart it without losing any state information. But there's more: > for example, some very peculiar services cannot be terminated on > shutdown (i.e. fakeraid DM stuff) and it would be really nice if the > services in question could just mark that on their cgroup, by setting an > xattr. On the more desktopy side of things there are other > possibilities: for example there are plans defining what an application > is along the lines of a cgroup (i.e. an app being a collection of > processes). With xattrs one could then attach an icon or human readable > program name on the cgroup. > > The key idea is that this would allow attaching runtime meta information > to cgroups and everything they model (services, apps, vms), that doesn't > need any complex userspace infrastructure, has good access control > (i.e. because the file system enforces that anyway, and there's the > "trusted." xattr namespace), notifications (inotify), and can easily be > shared among applications. > > Lennart v7: - no changes v6: - remove user xattr namespace, only allow trusted and security v5: - check for capabilities before setting/removing xattrs v4: - no changes v3: - instead of config option, use mount option to enable xattr support Original-patch-by: Li Zefan <lizefan@huawei.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Lennart Poettering <lpoetter@redhat.com> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Aristeu Rozanski <aris@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-08-24 00:53:30 +04:00
continue;
}
cgroup: make the mount options parsing more accurate Current behavior: ================= (1) When we mount a cgroup, we can specify the 'all' option which means to enable all the cgroup subsystems. This is the default option when no option is specified. (2) If we want to mount a cgroup with a subset of the supported cgroup subsystems, we have to specify a subsystems name list for the mount option. (3) If we specify another option like 'noprefix' or 'release_agent', the actual code wants the 'all' or a subsystem name option specified also. Not critical but a bit not friendly as we should assume (1) in this case. (4) Logically, the 'all' option is mutually exclusive with a subsystem name, but this is not detected. In other words: succeed : mount -t cgroup -o all,freezer cgroup /cgroup => is it 'all' or 'freezer' ? fails : mount -t cgroup -o noprefix cgroup /cgroup => succeed if we do '-o noprefix,all' The following patches consolidate a bit the mount options check. New behavior: ============= (1) untouched (2) untouched (3) the 'all' option will be by default when specifying other than a subsystem name option (4) raises an error In other words: fails : mount -t cgroup -o all,freezer cgroup /cgroup succeed : mount -t cgroup -o noprefix cgroup /cgroup For the sake of lisibility, the if ... then ... else ... if ... indentation when parsing the options has been changed to: if ... then ... continue fi Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:37 +04:00
if (!strncmp(token, "release_agent=", 14)) {
/* Specifying two release agents is forbidden */
if (opts->release_agent)
return -EINVAL;
opts->release_agent =
kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
if (!opts->release_agent)
return -ENOMEM;
cgroup: make the mount options parsing more accurate Current behavior: ================= (1) When we mount a cgroup, we can specify the 'all' option which means to enable all the cgroup subsystems. This is the default option when no option is specified. (2) If we want to mount a cgroup with a subset of the supported cgroup subsystems, we have to specify a subsystems name list for the mount option. (3) If we specify another option like 'noprefix' or 'release_agent', the actual code wants the 'all' or a subsystem name option specified also. Not critical but a bit not friendly as we should assume (1) in this case. (4) Logically, the 'all' option is mutually exclusive with a subsystem name, but this is not detected. In other words: succeed : mount -t cgroup -o all,freezer cgroup /cgroup => is it 'all' or 'freezer' ? fails : mount -t cgroup -o noprefix cgroup /cgroup => succeed if we do '-o noprefix,all' The following patches consolidate a bit the mount options check. New behavior: ============= (1) untouched (2) untouched (3) the 'all' option will be by default when specifying other than a subsystem name option (4) raises an error In other words: fails : mount -t cgroup -o all,freezer cgroup /cgroup succeed : mount -t cgroup -o noprefix cgroup /cgroup For the sake of lisibility, the if ... then ... else ... if ... indentation when parsing the options has been changed to: if ... then ... continue fi Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:37 +04:00
continue;
}
if (!strncmp(token, "name=", 5)) {
const char *name = token + 5;
/* Can't specify an empty name */
if (!strlen(name))
return -EINVAL;
/* Must match [\w.-]+ */
for (i = 0; i < strlen(name); i++) {
char c = name[i];
if (isalnum(c))
continue;
if ((c == '.') || (c == '-') || (c == '_'))
continue;
return -EINVAL;
}
/* Specifying two names is forbidden */
if (opts->name)
return -EINVAL;
opts->name = kstrndup(name,
MAX_CGROUP_ROOT_NAMELEN - 1,
GFP_KERNEL);
if (!opts->name)
return -ENOMEM;
cgroup: make the mount options parsing more accurate Current behavior: ================= (1) When we mount a cgroup, we can specify the 'all' option which means to enable all the cgroup subsystems. This is the default option when no option is specified. (2) If we want to mount a cgroup with a subset of the supported cgroup subsystems, we have to specify a subsystems name list for the mount option. (3) If we specify another option like 'noprefix' or 'release_agent', the actual code wants the 'all' or a subsystem name option specified also. Not critical but a bit not friendly as we should assume (1) in this case. (4) Logically, the 'all' option is mutually exclusive with a subsystem name, but this is not detected. In other words: succeed : mount -t cgroup -o all,freezer cgroup /cgroup => is it 'all' or 'freezer' ? fails : mount -t cgroup -o noprefix cgroup /cgroup => succeed if we do '-o noprefix,all' The following patches consolidate a bit the mount options check. New behavior: ============= (1) untouched (2) untouched (3) the 'all' option will be by default when specifying other than a subsystem name option (4) raises an error In other words: fails : mount -t cgroup -o all,freezer cgroup /cgroup succeed : mount -t cgroup -o noprefix cgroup /cgroup For the sake of lisibility, the if ... then ... else ... if ... indentation when parsing the options has been changed to: if ... then ... continue fi Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:37 +04:00
continue;
}
for_each_subsys(ss, i) {
if (strcmp(token, ss->legacy_name))
cgroup: make the mount options parsing more accurate Current behavior: ================= (1) When we mount a cgroup, we can specify the 'all' option which means to enable all the cgroup subsystems. This is the default option when no option is specified. (2) If we want to mount a cgroup with a subset of the supported cgroup subsystems, we have to specify a subsystems name list for the mount option. (3) If we specify another option like 'noprefix' or 'release_agent', the actual code wants the 'all' or a subsystem name option specified also. Not critical but a bit not friendly as we should assume (1) in this case. (4) Logically, the 'all' option is mutually exclusive with a subsystem name, but this is not detected. In other words: succeed : mount -t cgroup -o all,freezer cgroup /cgroup => is it 'all' or 'freezer' ? fails : mount -t cgroup -o noprefix cgroup /cgroup => succeed if we do '-o noprefix,all' The following patches consolidate a bit the mount options check. New behavior: ============= (1) untouched (2) untouched (3) the 'all' option will be by default when specifying other than a subsystem name option (4) raises an error In other words: fails : mount -t cgroup -o all,freezer cgroup /cgroup succeed : mount -t cgroup -o noprefix cgroup /cgroup For the sake of lisibility, the if ... then ... else ... if ... indentation when parsing the options has been changed to: if ... then ... continue fi Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:37 +04:00
continue;
if (!cgroup_ssid_enabled(i))
cgroup: make the mount options parsing more accurate Current behavior: ================= (1) When we mount a cgroup, we can specify the 'all' option which means to enable all the cgroup subsystems. This is the default option when no option is specified. (2) If we want to mount a cgroup with a subset of the supported cgroup subsystems, we have to specify a subsystems name list for the mount option. (3) If we specify another option like 'noprefix' or 'release_agent', the actual code wants the 'all' or a subsystem name option specified also. Not critical but a bit not friendly as we should assume (1) in this case. (4) Logically, the 'all' option is mutually exclusive with a subsystem name, but this is not detected. In other words: succeed : mount -t cgroup -o all,freezer cgroup /cgroup => is it 'all' or 'freezer' ? fails : mount -t cgroup -o noprefix cgroup /cgroup => succeed if we do '-o noprefix,all' The following patches consolidate a bit the mount options check. New behavior: ============= (1) untouched (2) untouched (3) the 'all' option will be by default when specifying other than a subsystem name option (4) raises an error In other words: fails : mount -t cgroup -o all,freezer cgroup /cgroup succeed : mount -t cgroup -o noprefix cgroup /cgroup For the sake of lisibility, the if ... then ... else ... if ... indentation when parsing the options has been changed to: if ... then ... continue fi Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:37 +04:00
continue;
if (cgroup_ssid_no_v1(i))
continue;
cgroup: make the mount options parsing more accurate Current behavior: ================= (1) When we mount a cgroup, we can specify the 'all' option which means to enable all the cgroup subsystems. This is the default option when no option is specified. (2) If we want to mount a cgroup with a subset of the supported cgroup subsystems, we have to specify a subsystems name list for the mount option. (3) If we specify another option like 'noprefix' or 'release_agent', the actual code wants the 'all' or a subsystem name option specified also. Not critical but a bit not friendly as we should assume (1) in this case. (4) Logically, the 'all' option is mutually exclusive with a subsystem name, but this is not detected. In other words: succeed : mount -t cgroup -o all,freezer cgroup /cgroup => is it 'all' or 'freezer' ? fails : mount -t cgroup -o noprefix cgroup /cgroup => succeed if we do '-o noprefix,all' The following patches consolidate a bit the mount options check. New behavior: ============= (1) untouched (2) untouched (3) the 'all' option will be by default when specifying other than a subsystem name option (4) raises an error In other words: fails : mount -t cgroup -o all,freezer cgroup /cgroup succeed : mount -t cgroup -o noprefix cgroup /cgroup For the sake of lisibility, the if ... then ... else ... if ... indentation when parsing the options has been changed to: if ... then ... continue fi Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:37 +04:00
/* Mutually exclusive option 'all' + subsystem name */
if (all_ss)
return -EINVAL;
opts->subsys_mask |= (1 << i);
cgroup: make the mount options parsing more accurate Current behavior: ================= (1) When we mount a cgroup, we can specify the 'all' option which means to enable all the cgroup subsystems. This is the default option when no option is specified. (2) If we want to mount a cgroup with a subset of the supported cgroup subsystems, we have to specify a subsystems name list for the mount option. (3) If we specify another option like 'noprefix' or 'release_agent', the actual code wants the 'all' or a subsystem name option specified also. Not critical but a bit not friendly as we should assume (1) in this case. (4) Logically, the 'all' option is mutually exclusive with a subsystem name, but this is not detected. In other words: succeed : mount -t cgroup -o all,freezer cgroup /cgroup => is it 'all' or 'freezer' ? fails : mount -t cgroup -o noprefix cgroup /cgroup => succeed if we do '-o noprefix,all' The following patches consolidate a bit the mount options check. New behavior: ============= (1) untouched (2) untouched (3) the 'all' option will be by default when specifying other than a subsystem name option (4) raises an error In other words: fails : mount -t cgroup -o all,freezer cgroup /cgroup succeed : mount -t cgroup -o noprefix cgroup /cgroup For the sake of lisibility, the if ... then ... else ... if ... indentation when parsing the options has been changed to: if ... then ... continue fi Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Reviewed-by: Paul Menage <menage@google.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:37 +04:00
one_ss = true;
break;
}
if (i == CGROUP_SUBSYS_COUNT)
return -ENOENT;
}
/*
* If the 'all' option was specified select all the subsystems,
* otherwise if 'none', 'name=' and a subsystem name options were
* not specified, let's default to 'all'
*/
if (all_ss || (!one_ss && !opts->none && !opts->name))
for_each_subsys(ss, i)
if (cgroup_ssid_enabled(i) && !cgroup_ssid_no_v1(i))
opts->subsys_mask |= (1 << i);
/*
* We either have to specify by name or by subsystems. (So all
* empty hierarchies must have a name).
*/
if (!opts->subsys_mask && !opts->name)
return -EINVAL;
/*
* Option noprefix was introduced just for backward compatibility
* with the old cpuset, so we allow noprefix only if mounting just
* the cpuset subsystem.
*/
if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
return -EINVAL;
/* Can't specify "none" and some subsystems */
if (opts->subsys_mask && opts->none)
return -EINVAL;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
return 0;
}
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
int ret = 0;
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
struct cgroup_sb_opts opts;
u16 added_mask, removed_mask;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
if (root == &cgrp_dfl_root) {
pr_err("remount is not allowed\n");
cgroup: introduce sane_behavior mount option It's a sad fact that at this point various cgroup controllers are carrying so many idiosyncrasies and pure insanities that it simply isn't possible to reach any sort of sane consistent behavior while maintaining staying fully compatible with what already has been exposed to userland. As we can't break exposed userland interface, transitioning to sane behaviors can only be done in steps while maintaining backwards compatibility. This patch introduces a new mount option - __DEVEL__sane_behavior - which disables crazy features and enforces consistent behaviors in cgroup core proper and various controllers. As exactly which behaviors it changes are still being determined, the mount option, at this point, is useful only for development of the new behaviors. As such, the mount option is prefixed with __DEVEL__ and generates a warning message when used. Eventually, once we get to the point where all controller's behaviors are consistent enough to implement unified hierarchy, the __DEVEL__ prefix will be dropped, and more importantly, unified-hierarchy will enforce sane_behavior by default. Maybe we'll able to completely drop the crazy stuff after a while, maybe not, but we at least have a strategy to move on to saner behaviors. This patch introduces the mount option and changes the following behaviors in cgroup core. * Mount options "noprefix" and "clone_children" are disallowed. Also, cgroupfs file cgroup.clone_children is not created. * When mounting an existing superblock, mount options should match. This is currently pretty crazy. If one mounts a cgroup, creates a subdirectory, unmounts it and then mount it again with different option, it looks like the new options are applied but they aren't. * Remount is disallowed. The behaviors changes are documented in the comment above CGRP_ROOT_SANE_BEHAVIOR enum and will be expanded as different controllers are converted and planned improvements progress. v2: Dropped unnecessary explicit file permission setting sane_behavior cftype entry as suggested by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com>
2013-04-15 07:15:26 +04:00
return -EINVAL;
}
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
mutex_lock(&cgroup_mutex);
/* See what subsystems are wanted */
ret = parse_cgroupfs_options(data, &opts);
if (ret)
goto out_unlock;
if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
task_tgid_nr(current), current->comm);
added_mask = opts.subsys_mask & ~root->subsys_mask;
removed_mask = root->subsys_mask & ~opts.subsys_mask;
/* Don't allow flags or name to change at remount */
if ((opts.flags ^ root->flags) ||
(opts.name && strcmp(opts.name, root->name))) {
pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
opts.flags, opts.name ?: "", root->flags, root->name);
ret = -EINVAL;
goto out_unlock;
}
/* remounting is not allowed for populated hierarchies */
if (!list_empty(&root->cgrp.self.children)) {
ret = -EBUSY;
goto out_unlock;
}
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
cgroup: treat cgroup_dummy_root as an equivalent hierarchy during rebinding Currently, while rebinding, cgroup_dummy_root serves as the anchor point. In addition to the target root, rebind_subsystems() takes @added_mask and @removed_mask. The subsystems specified in the former are expected to be on the dummy root and then moved to the target root. The ones in the latter are moved from non-dummy root to dummy. Now that the dummy root is a fully functional one and we're planning to use it for the default unified hierarchy, this level of distinction between dummy and non-dummy roots is quite awkward. This patch updates rebind_subsystems() to take the target root and one subsystem mask and move the specified subsystmes to the target root which may or may not be the dummy root. IOW, unbinding now becomes moving the subsystems to the dummy root and binding to non-dummy root. This makes the dummy root mostly equivalent to other hierarchies in terms of the mechanism of moving subsystems around; however, we still retain all the semantical restrictions so that this patch doesn't introduce any visible behavior differences. Another noteworthy detail is that rebind_subsystems() guarantees that moving a subsystem to the dummy root never fails so that valid unmounting attempts always succeed. This unifies binding and unbinding of subsystems. The invocation points of ->bind() were inconsistent between the two and now moved after whole rebinding is complete. This doesn't break the current users and generally makes more sense. All rebind_subsystems() users are converted accordingly. Note that cgroup_remount() now makes two calls to rebind_subsystems() to bind and then unbind the requested subsystems. This will allow repurposing of the dummy hierarchy as the default unified hierarchy and shouldn't make any userland visible behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-03-19 18:23:54 +04:00
ret = rebind_subsystems(root, added_mask);
cgroup: make rebind_subsystems() handle file additions and removals with proper error handling Currently, creating and removing cgroup files in the root directory are handled separately from the actual subsystem binding and unbinding which happens in rebind_subsystems(). Also, rebind_subsystems() users aren't handling file creation errors properly. Let's integrate top_cgroup file handling into rebind_subsystems() so that it's simpler to use and everyone handles file creation errors correctly. * On a successful return, rebind_subsystems() is guaranteed to have created all files of the new subsystems and deleted the ones belonging to the removed subsystems. After a failure, no file is created or removed. * cgroup_remount() no longer needs to make explicit populate/clear calls as it's all handled by rebind_subsystems(), and it gets proper error handling automatically. * cgroup_mount() has been updated such that the root dentry and cgroup are linked before rebind_subsystems(). Also, the init_cred dancing and base file handling are moved right above rebind_subsystems() call and proper error handling for the base files is added. While at it, add a comment explaining what's going on with the cred thing. * cgroup_kill_sb() calls rebind_subsystems() to unbind all subsystems which now implies removing all subsystem files which requires the directory's i_mutex. Grab it. This means that files on the root cgroup are removed earlier - they used to be deleted from generic super_block cleanup from vfs. This doesn't lead to any functional difference and it's cleaner to do the clean up explicitly for all files. Combined with the previous changes, this makes all cgroup file creation errors handled correctly. v2: Added comment on init_cred. v3: Li spotted that cgroup_mount() wasn't freeing tmp_links after base file addition failure. Fix it by adding free_tmp_links error handling label. v4: v3 introduced build bugs which got noticed by Fengguang's awesome kbuild test robot. Fixed, and shame on me. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com>
2013-06-29 04:07:30 +04:00
if (ret)
goto out_unlock;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
rebind_subsystems(&cgrp_dfl_root, removed_mask);
cgroup: treat cgroup_dummy_root as an equivalent hierarchy during rebinding Currently, while rebinding, cgroup_dummy_root serves as the anchor point. In addition to the target root, rebind_subsystems() takes @added_mask and @removed_mask. The subsystems specified in the former are expected to be on the dummy root and then moved to the target root. The ones in the latter are moved from non-dummy root to dummy. Now that the dummy root is a fully functional one and we're planning to use it for the default unified hierarchy, this level of distinction between dummy and non-dummy roots is quite awkward. This patch updates rebind_subsystems() to take the target root and one subsystem mask and move the specified subsystmes to the target root which may or may not be the dummy root. IOW, unbinding now becomes moving the subsystems to the dummy root and binding to non-dummy root. This makes the dummy root mostly equivalent to other hierarchies in terms of the mechanism of moving subsystems around; however, we still retain all the semantical restrictions so that this patch doesn't introduce any visible behavior differences. Another noteworthy detail is that rebind_subsystems() guarantees that moving a subsystem to the dummy root never fails so that valid unmounting attempts always succeed. This unifies binding and unbinding of subsystems. The invocation points of ->bind() were inconsistent between the two and now moved after whole rebinding is complete. This doesn't break the current users and generally makes more sense. All rebind_subsystems() users are converted accordingly. Note that cgroup_remount() now makes two calls to rebind_subsystems() to bind and then unbind the requested subsystems. This will allow repurposing of the dummy hierarchy as the default unified hierarchy and shouldn't make any userland visible behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-03-19 18:23:54 +04:00
if (opts.release_agent) {
spin_lock(&release_agent_path_lock);
strcpy(root->release_agent_path, opts.release_agent);
spin_unlock(&release_agent_path_lock);
}
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
out_unlock:
kfree(opts.release_agent);
kfree(opts.name);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
mutex_unlock(&cgroup_mutex);
return ret;
}
/*
* To reduce the fork() overhead for systems that are not actually using
* their cgroups capability, we don't maintain the lists running through
* each css_set to its tasks until we see the list actually used - in other
* words after the first mount.
*/
static bool use_task_css_set_links __read_mostly;
static void cgroup_enable_task_cg_lists(void)
{
struct task_struct *p, *g;
spin_lock_bh(&css_set_lock);
if (use_task_css_set_links)
goto out_unlock;
use_task_css_set_links = true;
/*
* We need tasklist_lock because RCU is not safe against
* while_each_thread(). Besides, a forking task that has passed
* cgroup_post_fork() without seeing use_task_css_set_links = 1
* is not guaranteed to have its child immediately visible in the
* tasklist if we walk through it with RCU.
*/
read_lock(&tasklist_lock);
do_each_thread(g, p) {
WARN_ON_ONCE(!list_empty(&p->cg_list) ||
task_css_set(p) != &init_css_set);
/*
* We should check if the process is exiting, otherwise
* it will race with cgroup_exit() in that the list
* entry won't be deleted though the process has exited.
* Do it while holding siglock so that we don't end up
* racing against cgroup_exit().
*/
spin_lock_irq(&p->sighand->siglock);
cgroup: update how a newly forked task gets associated with css_set When a new process is forked, cgroup_fork() associates it with the css_set of its parent but doesn't link it into it. After the new process is linked to tasklist, cgroup_post_fork() does the linking. This is problematic for cgroup_transfer_tasks() as there's no way to tell whether there are tasks which are pointing to a css_set but not linked yet. It is impossible to implement an operation which transfer all tasks of a cgroup to another and the current cgroup_transfer_tasks() can easily be tricked into leaving a newly forked process behind if it gets called between cgroup_fork() and cgroup_post_fork(). Let's make association with a css_set and linking atomic by moving it to cgroup_post_fork(). cgroup_fork() sets child->cgroups to init_css_set as a placeholder and cgroup_post_fork() is updated to perform both the association with the parent's cgroup and linking there. This means that a newly created task will point to init_css_set without holding a ref to it much like what it does on the exit path. Empty cg_list is used to indicate that the task isn't holding a ref to the associated css_set. This fixes an actual bug with cgroup_transfer_tasks(); however, I'm not marking it for -stable. The whole thing is broken in multiple other ways which require invasive updates to fix and I don't think it's worthwhile to bother with backporting this particular one. Fortunately, the only user is cpuset and these bugs don't crash the machine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
if (!(p->flags & PF_EXITING)) {
struct css_set *cset = task_css_set(p);
if (!css_set_populated(cset))
css_set_update_populated(cset, true);
list_add_tail(&p->cg_list, &cset->tasks);
cgroup: update how a newly forked task gets associated with css_set When a new process is forked, cgroup_fork() associates it with the css_set of its parent but doesn't link it into it. After the new process is linked to tasklist, cgroup_post_fork() does the linking. This is problematic for cgroup_transfer_tasks() as there's no way to tell whether there are tasks which are pointing to a css_set but not linked yet. It is impossible to implement an operation which transfer all tasks of a cgroup to another and the current cgroup_transfer_tasks() can easily be tricked into leaving a newly forked process behind if it gets called between cgroup_fork() and cgroup_post_fork(). Let's make association with a css_set and linking atomic by moving it to cgroup_post_fork(). cgroup_fork() sets child->cgroups to init_css_set as a placeholder and cgroup_post_fork() is updated to perform both the association with the parent's cgroup and linking there. This means that a newly created task will point to init_css_set without holding a ref to it much like what it does on the exit path. Empty cg_list is used to indicate that the task isn't holding a ref to the associated css_set. This fixes an actual bug with cgroup_transfer_tasks(); however, I'm not marking it for -stable. The whole thing is broken in multiple other ways which require invasive updates to fix and I don't think it's worthwhile to bother with backporting this particular one. Fortunately, the only user is cpuset and these bugs don't crash the machine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
get_css_set(cset);
}
spin_unlock_irq(&p->sighand->siglock);
} while_each_thread(g, p);
read_unlock(&tasklist_lock);
out_unlock:
spin_unlock_bh(&css_set_lock);
}
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
static void init_cgroup_housekeeping(struct cgroup *cgrp)
{
struct cgroup_subsys *ss;
int ssid;
INIT_LIST_HEAD(&cgrp->self.sibling);
INIT_LIST_HEAD(&cgrp->self.children);
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
INIT_LIST_HEAD(&cgrp->cset_links);
INIT_LIST_HEAD(&cgrp->pidlists);
mutex_init(&cgrp->pidlist_mutex);
cgrp->self.cgroup = cgrp;
cgrp->self.flags |= CSS_ONLINE;
for_each_subsys(ss, ssid)
INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
init_waitqueue_head(&cgrp->offline_waitq);
INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent);
}
static void init_cgroup_root(struct cgroup_root *root,
struct cgroup_sb_opts *opts)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
struct cgroup *cgrp = &root->cgrp;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
INIT_LIST_HEAD(&root->root_list);
atomic_set(&root->nr_cgrps, 1);
cgrp->root = root;
init_cgroup_housekeeping(cgrp);
idr_init(&root->cgroup_idr);
root->flags = opts->flags;
if (opts->release_agent)
strcpy(root->release_agent_path, opts->release_agent);
if (opts->name)
strcpy(root->name, opts->name);
if (opts->cpuset_clone_children)
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
}
static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
{
LIST_HEAD(tmp_links);
struct cgroup *root_cgrp = &root->cgrp;
struct css_set *cset;
int i, ret;
lockdep_assert_held(&cgroup_mutex);
ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL);
if (ret < 0)
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
goto out;
root_cgrp->id = ret;
root_cgrp->ancestor_ids[0] = ret;
ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, 0,
GFP_KERNEL);
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
if (ret)
goto out;
/*
* We're accessing css_set_count without locking css_set_lock here,
* but that's OK - it can only be increased by someone holding
* cgroup_lock, and that's us. The worst that can happen is that we
* have some link structures left over
*/
ret = allocate_cgrp_cset_links(css_set_count, &tmp_links);
if (ret)
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
goto cancel_ref;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
ret = cgroup_init_root_id(root);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
if (ret)
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
goto cancel_ref;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops,
KERNFS_ROOT_CREATE_DEACTIVATED,
root_cgrp);
if (IS_ERR(root->kf_root)) {
ret = PTR_ERR(root->kf_root);
goto exit_root_id;
}
root_cgrp->kn = root->kf_root->kn;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
ret = css_populate_dir(&root_cgrp->self, NULL);
if (ret)
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
goto destroy_root;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
cgroup: treat cgroup_dummy_root as an equivalent hierarchy during rebinding Currently, while rebinding, cgroup_dummy_root serves as the anchor point. In addition to the target root, rebind_subsystems() takes @added_mask and @removed_mask. The subsystems specified in the former are expected to be on the dummy root and then moved to the target root. The ones in the latter are moved from non-dummy root to dummy. Now that the dummy root is a fully functional one and we're planning to use it for the default unified hierarchy, this level of distinction between dummy and non-dummy roots is quite awkward. This patch updates rebind_subsystems() to take the target root and one subsystem mask and move the specified subsystmes to the target root which may or may not be the dummy root. IOW, unbinding now becomes moving the subsystems to the dummy root and binding to non-dummy root. This makes the dummy root mostly equivalent to other hierarchies in terms of the mechanism of moving subsystems around; however, we still retain all the semantical restrictions so that this patch doesn't introduce any visible behavior differences. Another noteworthy detail is that rebind_subsystems() guarantees that moving a subsystem to the dummy root never fails so that valid unmounting attempts always succeed. This unifies binding and unbinding of subsystems. The invocation points of ->bind() were inconsistent between the two and now moved after whole rebinding is complete. This doesn't break the current users and generally makes more sense. All rebind_subsystems() users are converted accordingly. Note that cgroup_remount() now makes two calls to rebind_subsystems() to bind and then unbind the requested subsystems. This will allow repurposing of the dummy hierarchy as the default unified hierarchy and shouldn't make any userland visible behavior difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-03-19 18:23:54 +04:00
ret = rebind_subsystems(root, ss_mask);
if (ret)
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
goto destroy_root;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/*
* There must be no failure case after here, since rebinding takes
* care of subsystems' refcounts, which are explicitly dropped in
* the failure exit path.
*/
list_add(&root->root_list, &cgroup_roots);
cgroup_root_count++;
/*
* Link the root cgroup in this hierarchy into all the css_set
* objects.
*/
spin_lock_bh(&css_set_lock);
hash_for_each(css_set_table, i, cset, hlist) {
link_css_set(&tmp_links, cset, root_cgrp);
if (css_set_populated(cset))
cgroup_update_populated(root_cgrp, true);
}
spin_unlock_bh(&css_set_lock);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
BUG_ON(!list_empty(&root_cgrp->self.children));
BUG_ON(atomic_read(&root->nr_cgrps) != 1);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
kernfs_activate(root_cgrp->kn);
ret = 0;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
goto out;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
destroy_root:
kernfs_destroy_root(root->kf_root);
root->kf_root = NULL;
exit_root_id:
cgroup_exit_root_id(root);
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
cancel_ref:
percpu_ref_exit(&root_cgrp->self.refcnt);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
out:
free_cgrp_cset_links(&tmp_links);
return ret;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
static struct dentry *cgroup_mount(struct file_system_type *fs_type,
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
int flags, const char *unused_dev_name,
void *data)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
bool is_v2 = fs_type == &cgroup2_fs_type;
struct super_block *pinned_sb = NULL;
struct cgroup_subsys *ss;
struct cgroup_root *root;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
struct cgroup_sb_opts opts;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct dentry *dentry;
int ret;
int i;
bool new_sb;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/*
* The first time anyone tries to mount a cgroup, enable the list
* linking each css_set to its tasks and fix up all existing tasks.
*/
if (!use_task_css_set_links)
cgroup_enable_task_cg_lists();
if (is_v2) {
if (data) {
pr_err("cgroup2: unknown option \"%s\"\n", (char *)data);
return ERR_PTR(-EINVAL);
}
cgrp_dfl_visible = true;
root = &cgrp_dfl_root;
cgroup_get(&root->cgrp);
goto out_mount;
}
cgroups: revamp subsys array This patch series provides the ability for cgroup subsystems to be compiled as modules both within and outside the kernel tree. This is mainly useful for classifiers and subsystems that hook into components that are already modules. cls_cgroup and blkio-cgroup serve as the example use cases for this feature. It provides an interface cgroup_load_subsys() and cgroup_unload_subsys() which modular subsystems can use to register and depart during runtime. The net_cls classifier subsystem serves as the example for a subsystem which can be converted into a module using these changes. Patch #1 sets up the subsys[] array so its contents can be dynamic as modules appear and (eventually) disappear. Iterations over the array are modified to handle when subsystems are absent, and the dynamic section of the array is protected by cgroup_mutex. Patch #2 implements an interface for modules to load subsystems, called cgroup_load_subsys, similar to cgroup_init_subsys, and adds a module pointer in struct cgroup_subsys. Patch #3 adds a mechanism for unloading modular subsystems, which includes a more advanced rework of the rudimentary reference counting introduced in patch 2. Patch #4 modifies the net_cls subsystem, which already had some module declarations, to be configurable as a module, which also serves as a simple proof-of-concept. Part of implementing patches 2 and 4 involved updating css pointers in each css_set when the module appears or leaves. In doing this, it was discovered that css_sets always remain linked to the dummy cgroup, regardless of whether or not any subsystems are actually bound to it (i.e., not mounted on an actual hierarchy). The subsystem loading and unloading code therefore should keep in mind the special cases where the added subsystem is the only one in the dummy cgroup (and therefore all css_sets need to be linked back into it) and where the removed subsys was the only one in the dummy cgroup (and therefore all css_sets should be unlinked from it) - however, as all css_sets always stay attached to the dummy cgroup anyway, these cases are ignored. Any fix that addresses this issue should also make sure these cases are addressed in the subsystem loading and unloading code. This patch: Make subsys[] able to be dynamically populated to support modular subsystems This patch reworks the way the subsys[] array is used so that subsystems can register themselves after boot time, and enables the internals of cgroups to be able to handle when subsystems are not present or may appear/disappear. Signed-off-by: Ben Blum <bblum@andrew.cmu.edu> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-11 02:22:07 +03:00
mutex_lock(&cgroup_mutex);
/* First find the desired set of subsystems */
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
ret = parse_cgroupfs_options(data, &opts);
if (ret)
goto out_unlock;
/*
* Destruction of cgroup root is asynchronous, so subsystems may
* still be dying after the previous unmount. Let's drain the
* dying subsystems. We just need to ensure that the ones
* unmounted previously finish dying and don't care about new ones
* starting. Testing ref liveliness is good enough.
*/
for_each_subsys(ss, i) {
if (!(opts.subsys_mask & (1 << i)) ||
ss->root == &cgrp_dfl_root)
continue;
if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
mutex_unlock(&cgroup_mutex);
msleep(10);
ret = restart_syscall();
goto out_free;
}
cgroup_put(&ss->root->cgrp);
}
for_each_root(root) {
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
bool name_match = false;
cgroup: make rebind_subsystems() handle file additions and removals with proper error handling Currently, creating and removing cgroup files in the root directory are handled separately from the actual subsystem binding and unbinding which happens in rebind_subsystems(). Also, rebind_subsystems() users aren't handling file creation errors properly. Let's integrate top_cgroup file handling into rebind_subsystems() so that it's simpler to use and everyone handles file creation errors correctly. * On a successful return, rebind_subsystems() is guaranteed to have created all files of the new subsystems and deleted the ones belonging to the removed subsystems. After a failure, no file is created or removed. * cgroup_remount() no longer needs to make explicit populate/clear calls as it's all handled by rebind_subsystems(), and it gets proper error handling automatically. * cgroup_mount() has been updated such that the root dentry and cgroup are linked before rebind_subsystems(). Also, the init_cred dancing and base file handling are moved right above rebind_subsystems() call and proper error handling for the base files is added. While at it, add a comment explaining what's going on with the cred thing. * cgroup_kill_sb() calls rebind_subsystems() to unbind all subsystems which now implies removing all subsystem files which requires the directory's i_mutex. Grab it. This means that files on the root cgroup are removed earlier - they used to be deleted from generic super_block cleanup from vfs. This doesn't lead to any functional difference and it's cleaner to do the clean up explicitly for all files. Combined with the previous changes, this makes all cgroup file creation errors handled correctly. v2: Added comment on init_cred. v3: Li spotted that cgroup_mount() wasn't freeing tmp_links after base file addition failure. Fix it by adding free_tmp_links error handling label. v4: v3 introduced build bugs which got noticed by Fengguang's awesome kbuild test robot. Fixed, and shame on me. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com>
2013-06-29 04:07:30 +04:00
if (root == &cgrp_dfl_root)
continue;
cgroup: make rebind_subsystems() handle file additions and removals with proper error handling Currently, creating and removing cgroup files in the root directory are handled separately from the actual subsystem binding and unbinding which happens in rebind_subsystems(). Also, rebind_subsystems() users aren't handling file creation errors properly. Let's integrate top_cgroup file handling into rebind_subsystems() so that it's simpler to use and everyone handles file creation errors correctly. * On a successful return, rebind_subsystems() is guaranteed to have created all files of the new subsystems and deleted the ones belonging to the removed subsystems. After a failure, no file is created or removed. * cgroup_remount() no longer needs to make explicit populate/clear calls as it's all handled by rebind_subsystems(), and it gets proper error handling automatically. * cgroup_mount() has been updated such that the root dentry and cgroup are linked before rebind_subsystems(). Also, the init_cred dancing and base file handling are moved right above rebind_subsystems() call and proper error handling for the base files is added. While at it, add a comment explaining what's going on with the cred thing. * cgroup_kill_sb() calls rebind_subsystems() to unbind all subsystems which now implies removing all subsystem files which requires the directory's i_mutex. Grab it. This means that files on the root cgroup are removed earlier - they used to be deleted from generic super_block cleanup from vfs. This doesn't lead to any functional difference and it's cleaner to do the clean up explicitly for all files. Combined with the previous changes, this makes all cgroup file creation errors handled correctly. v2: Added comment on init_cred. v3: Li spotted that cgroup_mount() wasn't freeing tmp_links after base file addition failure. Fix it by adding free_tmp_links error handling label. v4: v3 introduced build bugs which got noticed by Fengguang's awesome kbuild test robot. Fixed, and shame on me. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com>
2013-06-29 04:07:30 +04:00
/*
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
* If we asked for a name then it must match. Also, if
* name matches but sybsys_mask doesn't, we should fail.
* Remember whether name matched.
*/
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
if (opts.name) {
if (strcmp(opts.name, root->name))
continue;
name_match = true;
}
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/*
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
* If we asked for subsystems (or explicitly for no
* subsystems) then they must match.
*/
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
if ((opts.subsys_mask || opts.none) &&
(opts.subsys_mask != root->subsys_mask)) {
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
if (!name_match)
continue;
ret = -EBUSY;
goto out_unlock;
}
cgroup: introduce sane_behavior mount option It's a sad fact that at this point various cgroup controllers are carrying so many idiosyncrasies and pure insanities that it simply isn't possible to reach any sort of sane consistent behavior while maintaining staying fully compatible with what already has been exposed to userland. As we can't break exposed userland interface, transitioning to sane behaviors can only be done in steps while maintaining backwards compatibility. This patch introduces a new mount option - __DEVEL__sane_behavior - which disables crazy features and enforces consistent behaviors in cgroup core proper and various controllers. As exactly which behaviors it changes are still being determined, the mount option, at this point, is useful only for development of the new behaviors. As such, the mount option is prefixed with __DEVEL__ and generates a warning message when used. Eventually, once we get to the point where all controller's behaviors are consistent enough to implement unified hierarchy, the __DEVEL__ prefix will be dropped, and more importantly, unified-hierarchy will enforce sane_behavior by default. Maybe we'll able to completely drop the crazy stuff after a while, maybe not, but we at least have a strategy to move on to saner behaviors. This patch introduces the mount option and changes the following behaviors in cgroup core. * Mount options "noprefix" and "clone_children" are disallowed. Also, cgroupfs file cgroup.clone_children is not created. * When mounting an existing superblock, mount options should match. This is currently pretty crazy. If one mounts a cgroup, creates a subdirectory, unmounts it and then mount it again with different option, it looks like the new options are applied but they aren't. * Remount is disallowed. The behaviors changes are documented in the comment above CGRP_ROOT_SANE_BEHAVIOR enum and will be expanded as different controllers are converted and planned improvements progress. v2: Dropped unnecessary explicit file permission setting sane_behavior cftype entry as suggested by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com>
2013-04-15 07:15:26 +04:00
if (root->flags ^ opts.flags)
pr_warn("new mount options do not match the existing superblock, will be ignored\n");
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/*
* We want to reuse @root whose lifetime is governed by its
* ->cgrp. Let's check whether @root is alive and keep it
* that way. As cgroup_kill_sb() can happen anytime, we
* want to block it by pinning the sb so that @root doesn't
* get killed before mount is complete.
*
* With the sb pinned, tryget_live can reliably indicate
* whether @root can be reused. If it's being killed,
* drain it. We can use wait_queue for the wait but this
* path is super cold. Let's just sleep a bit and retry.
*/
pinned_sb = kernfs_pin_sb(root->kf_root, NULL);
if (IS_ERR(pinned_sb) ||
!percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
mutex_unlock(&cgroup_mutex);
if (!IS_ERR_OR_NULL(pinned_sb))
deactivate_super(pinned_sb);
msleep(10);
ret = restart_syscall();
goto out_free;
}
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
ret = 0;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
goto out_unlock;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
/*
* No such thing, create a new one. name= matching without subsys
* specification is allowed for already existing hierarchies but we
* can't create new one without subsys specification.
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
*/
if (!opts.subsys_mask && !opts.none) {
ret = -EINVAL;
goto out_unlock;
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
}
root = kzalloc(sizeof(*root), GFP_KERNEL);
if (!root) {
ret = -ENOMEM;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
goto out_unlock;
}
init_cgroup_root(root, &opts);
ret = cgroup_setup_root(root, opts.subsys_mask);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
if (ret)
cgroup_free_root(root);
out_unlock:
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
mutex_unlock(&cgroup_mutex);
out_free:
kfree(opts.release_agent);
kfree(opts.name);
cgroup: add xattr support This is one of the items in the plumber's wish list. For use cases: >> What would the use case be for this? > > Attaching meta information to services, in an easily discoverable > way. For example, in systemd we create one cgroup for each service, and > could then store data like the main pid of the specific service as an > xattr on the cgroup itself. That way we'd have almost all service state > in the cgroupfs, which would make it possible to terminate systemd and > later restart it without losing any state information. But there's more: > for example, some very peculiar services cannot be terminated on > shutdown (i.e. fakeraid DM stuff) and it would be really nice if the > services in question could just mark that on their cgroup, by setting an > xattr. On the more desktopy side of things there are other > possibilities: for example there are plans defining what an application > is along the lines of a cgroup (i.e. an app being a collection of > processes). With xattrs one could then attach an icon or human readable > program name on the cgroup. > > The key idea is that this would allow attaching runtime meta information > to cgroups and everything they model (services, apps, vms), that doesn't > need any complex userspace infrastructure, has good access control > (i.e. because the file system enforces that anyway, and there's the > "trusted." xattr namespace), notifications (inotify), and can easily be > shared among applications. > > Lennart v7: - no changes v6: - remove user xattr namespace, only allow trusted and security v5: - check for capabilities before setting/removing xattrs v4: - no changes v3: - instead of config option, use mount option to enable xattr support Original-patch-by: Li Zefan <lizefan@huawei.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Lennart Poettering <lpoetter@redhat.com> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Aristeu Rozanski <aris@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2012-08-24 00:53:30 +04:00
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
if (ret)
return ERR_PTR(ret);
out_mount:
dentry = kernfs_mount(fs_type, flags, root->kf_root,
is_v2 ? CGROUP2_SUPER_MAGIC : CGROUP_SUPER_MAGIC,
&new_sb);
if (IS_ERR(dentry) || !new_sb)
cgroup_put(&root->cgrp);
/*
* If @pinned_sb, we're reusing an existing root and holding an
* extra ref on its sb. Mount is complete. Put the extra ref.
*/
if (pinned_sb) {
WARN_ON(new_sb);
deactivate_super(pinned_sb);
}
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
return dentry;
}
static void cgroup_kill_sb(struct super_block *sb)
{
struct kernfs_root *kf_root = kernfs_root_from_sb(sb);
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
/*
* If @root doesn't have any mounts or children, start killing it.
* This prevents new mounts by disabling percpu_ref_tryget_live().
* cgroup_mount() may wait for @root's release.
*
* And don't kill the default root.
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
*/
if (!list_empty(&root->cgrp.self.children) ||
root == &cgrp_dfl_root)
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
cgroup_put(&root->cgrp);
else
percpu_ref_kill(&root->cgrp.self.refcnt);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
kernfs_kill_sb(sb);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
static struct file_system_type cgroup_fs_type = {
.name = "cgroup",
.mount = cgroup_mount,
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
.kill_sb = cgroup_kill_sb,
};
static struct file_system_type cgroup2_fs_type = {
.name = "cgroup2",
.mount = cgroup_mount,
.kill_sb = cgroup_kill_sb,
};
/**
* task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
* @task: target task
* @buf: the buffer to write the path into
* @buflen: the length of the buffer
*
* Determine @task's cgroup on the first (the one with the lowest non-zero
* hierarchy_id) cgroup hierarchy and copy its path into @buf. This
* function grabs cgroup_mutex and shouldn't be used inside locks used by
* cgroup controller callbacks.
*
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
* Return value is the same as kernfs_path().
*/
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
{
struct cgroup_root *root;
struct cgroup *cgrp;
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
int hierarchy_id = 1;
char *path = NULL;
mutex_lock(&cgroup_mutex);
spin_lock_bh(&css_set_lock);
root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
if (root) {
cgrp = task_cgroup_from_root(task, root);
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
path = cgroup_path(cgrp, buf, buflen);
} else {
/* if no hierarchy exists, everyone is in "/" */
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
if (strlcpy(buf, "/", buflen) < buflen)
path = buf;
}
spin_unlock_bh(&css_set_lock);
mutex_unlock(&cgroup_mutex);
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
return path;
}
EXPORT_SYMBOL_GPL(task_cgroup_path);
cgroup: use css_set->mg_tasks to track target tasks during migration Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, this patch updates the migration path to use task->cg_list to track target tasks. The previous patch already added css_set->mg_tasks and updated iterations in non-migration paths to include them during task migration. This patch updates migration path to actually make use of it. Instead of putting onto a flex_array, each target task is moved from its css_set->tasks list to css_set->mg_tasks and the migration path keeps trace of all the source css_sets and the associated cgroups. Once all source css_sets are determined, the destination css_set for each is determined, linked to the matching source css_set and put on a separate list. To iterate the target tasks, migration path just needs to iterat through either the source or target css_sets, depending on whether migration has been committed or not, and the tasks on their ->mg_tasks lists. cgroup_taskset is updated to contain the list_heads for source and target css_sets and the iteration cursor. cgroup_taskset_*() are accordingly updated to walk through css_sets and their ->mg_tasks. This resolves the above listed issues with moderate additional complexity. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
/* used to track tasks and other necessary states during migration */
struct cgroup_taskset {
cgroup: use css_set->mg_tasks to track target tasks during migration Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, this patch updates the migration path to use task->cg_list to track target tasks. The previous patch already added css_set->mg_tasks and updated iterations in non-migration paths to include them during task migration. This patch updates migration path to actually make use of it. Instead of putting onto a flex_array, each target task is moved from its css_set->tasks list to css_set->mg_tasks and the migration path keeps trace of all the source css_sets and the associated cgroups. Once all source css_sets are determined, the destination css_set for each is determined, linked to the matching source css_set and put on a separate list. To iterate the target tasks, migration path just needs to iterat through either the source or target css_sets, depending on whether migration has been committed or not, and the tasks on their ->mg_tasks lists. cgroup_taskset is updated to contain the list_heads for source and target css_sets and the iteration cursor. cgroup_taskset_*() are accordingly updated to walk through css_sets and their ->mg_tasks. This resolves the above listed issues with moderate additional complexity. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
/* the src and dst cset list running through cset->mg_node */
struct list_head src_csets;
struct list_head dst_csets;
cgroup: fix handling of multi-destination migration from subtree_control enabling Consider the following v2 hierarchy. P0 (+memory) --- P1 (-memory) --- A \- B P0 has memory enabled in its subtree_control while P1 doesn't. If both A and B contain processes, they would belong to the memory css of P1. Now if memory is enabled on P1's subtree_control, memory csses should be created on both A and B and A's processes should be moved to the former and B's processes the latter. IOW, enabling controllers can cause atomic migrations into different csses. The core cgroup migration logic has been updated accordingly but the controller migration methods haven't and still assume that all tasks migrate to a single target css; furthermore, the methods were fed the css in which subtree_control was updated which is the parent of the target csses. pids controller depends on the migration methods to move charges and this made the controller attribute charges to the wrong csses often triggering the following warning by driving a counter negative. WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40() Modules linked in: CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29 ... ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000 ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00 ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8 Call Trace: [<ffffffff81551ffc>] dump_stack+0x4e/0x82 [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0 [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20 [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40 [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0 [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330 [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190 [<ffffffff81189016>] cgroup_attach_task+0x176/0x200 [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460 [<ffffffff81189684>] cgroup_procs_write+0x14/0x20 [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0 [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190 [<ffffffff81265f88>] __vfs_write+0x28/0xe0 [<ffffffff812666fc>] vfs_write+0xac/0x1a0 [<ffffffff81267019>] SyS_write+0x49/0xb0 [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76 This patch fixes the bug by removing @css parameter from the three migration methods, ->can_attach, ->cancel_attach() and ->attach() and updating cgroup_taskset iteration helpers also return the destination css in addition to the task being migrated. All controllers are updated accordingly. * Controllers which don't care whether there are one or multiple target csses can be converted trivially. cpu, io, freezer, perf, netclassid and netprio fall in this category. * cpuset's current implementation assumes that there's single source and destination and thus doesn't support v2 hierarchy already. The only change made by this patchset is how that single destination css is obtained. * memory migration path already doesn't do anything on v2. How the single destination css is obtained is updated and the prep stage of mem_cgroup_can_attach() is reordered to accomodate the change. * pids is the only controller which was affected by this bug. It now correctly handles multi-destination migrations and no longer causes counter underflow from incorrect accounting. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 18:18:21 +03:00
/* the subsys currently being processed */
int ssid;
cgroup: use css_set->mg_tasks to track target tasks during migration Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, this patch updates the migration path to use task->cg_list to track target tasks. The previous patch already added css_set->mg_tasks and updated iterations in non-migration paths to include them during task migration. This patch updates migration path to actually make use of it. Instead of putting onto a flex_array, each target task is moved from its css_set->tasks list to css_set->mg_tasks and the migration path keeps trace of all the source css_sets and the associated cgroups. Once all source css_sets are determined, the destination css_set for each is determined, linked to the matching source css_set and put on a separate list. To iterate the target tasks, migration path just needs to iterat through either the source or target css_sets, depending on whether migration has been committed or not, and the tasks on their ->mg_tasks lists. cgroup_taskset is updated to contain the list_heads for source and target css_sets and the iteration cursor. cgroup_taskset_*() are accordingly updated to walk through css_sets and their ->mg_tasks. This resolves the above listed issues with moderate additional complexity. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
/*
* Fields for cgroup_taskset_*() iteration.
*
* Before migration is committed, the target migration tasks are on
* ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of
* the csets on ->dst_csets. ->csets point to either ->src_csets
* or ->dst_csets depending on whether migration is committed.
*
* ->cur_csets and ->cur_task point to the current task position
* during iteration.
*/
struct list_head *csets;
struct css_set *cur_cset;
struct task_struct *cur_task;
};
#define CGROUP_TASKSET_INIT(tset) (struct cgroup_taskset){ \
.src_csets = LIST_HEAD_INIT(tset.src_csets), \
.dst_csets = LIST_HEAD_INIT(tset.dst_csets), \
.csets = &tset.src_csets, \
}
/**
* cgroup_taskset_add - try to add a migration target task to a taskset
* @task: target task
* @tset: target taskset
*
* Add @task, which is a migration target, to @tset. This function becomes
* noop if @task doesn't need to be migrated. @task's css_set should have
* been added as a migration source and @task->cg_list will be moved from
* the css_set's tasks list to mg_tasks one.
*/
static void cgroup_taskset_add(struct task_struct *task,
struct cgroup_taskset *tset)
{
struct css_set *cset;
lockdep_assert_held(&css_set_lock);
/* @task either already exited or can't exit until the end */
if (task->flags & PF_EXITING)
return;
/* leave @task alone if post_fork() hasn't linked it yet */
if (list_empty(&task->cg_list))
return;
cset = task_css_set(task);
if (!cset->mg_src_cgrp)
return;
list_move_tail(&task->cg_list, &cset->mg_tasks);
if (list_empty(&cset->mg_node))
list_add_tail(&cset->mg_node, &tset->src_csets);
if (list_empty(&cset->mg_dst_cset->mg_node))
list_move_tail(&cset->mg_dst_cset->mg_node,
&tset->dst_csets);
}
/**
* cgroup_taskset_first - reset taskset and return the first task
* @tset: taskset of interest
cgroup: fix handling of multi-destination migration from subtree_control enabling Consider the following v2 hierarchy. P0 (+memory) --- P1 (-memory) --- A \- B P0 has memory enabled in its subtree_control while P1 doesn't. If both A and B contain processes, they would belong to the memory css of P1. Now if memory is enabled on P1's subtree_control, memory csses should be created on both A and B and A's processes should be moved to the former and B's processes the latter. IOW, enabling controllers can cause atomic migrations into different csses. The core cgroup migration logic has been updated accordingly but the controller migration methods haven't and still assume that all tasks migrate to a single target css; furthermore, the methods were fed the css in which subtree_control was updated which is the parent of the target csses. pids controller depends on the migration methods to move charges and this made the controller attribute charges to the wrong csses often triggering the following warning by driving a counter negative. WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40() Modules linked in: CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29 ... ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000 ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00 ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8 Call Trace: [<ffffffff81551ffc>] dump_stack+0x4e/0x82 [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0 [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20 [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40 [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0 [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330 [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190 [<ffffffff81189016>] cgroup_attach_task+0x176/0x200 [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460 [<ffffffff81189684>] cgroup_procs_write+0x14/0x20 [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0 [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190 [<ffffffff81265f88>] __vfs_write+0x28/0xe0 [<ffffffff812666fc>] vfs_write+0xac/0x1a0 [<ffffffff81267019>] SyS_write+0x49/0xb0 [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76 This patch fixes the bug by removing @css parameter from the three migration methods, ->can_attach, ->cancel_attach() and ->attach() and updating cgroup_taskset iteration helpers also return the destination css in addition to the task being migrated. All controllers are updated accordingly. * Controllers which don't care whether there are one or multiple target csses can be converted trivially. cpu, io, freezer, perf, netclassid and netprio fall in this category. * cpuset's current implementation assumes that there's single source and destination and thus doesn't support v2 hierarchy already. The only change made by this patchset is how that single destination css is obtained. * memory migration path already doesn't do anything on v2. How the single destination css is obtained is updated and the prep stage of mem_cgroup_can_attach() is reordered to accomodate the change. * pids is the only controller which was affected by this bug. It now correctly handles multi-destination migrations and no longer causes counter underflow from incorrect accounting. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 18:18:21 +03:00
* @dst_cssp: output variable for the destination css
*
* @tset iteration is initialized and the first task is returned.
*/
cgroup: fix handling of multi-destination migration from subtree_control enabling Consider the following v2 hierarchy. P0 (+memory) --- P1 (-memory) --- A \- B P0 has memory enabled in its subtree_control while P1 doesn't. If both A and B contain processes, they would belong to the memory css of P1. Now if memory is enabled on P1's subtree_control, memory csses should be created on both A and B and A's processes should be moved to the former and B's processes the latter. IOW, enabling controllers can cause atomic migrations into different csses. The core cgroup migration logic has been updated accordingly but the controller migration methods haven't and still assume that all tasks migrate to a single target css; furthermore, the methods were fed the css in which subtree_control was updated which is the parent of the target csses. pids controller depends on the migration methods to move charges and this made the controller attribute charges to the wrong csses often triggering the following warning by driving a counter negative. WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40() Modules linked in: CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29 ... ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000 ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00 ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8 Call Trace: [<ffffffff81551ffc>] dump_stack+0x4e/0x82 [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0 [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20 [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40 [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0 [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330 [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190 [<ffffffff81189016>] cgroup_attach_task+0x176/0x200 [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460 [<ffffffff81189684>] cgroup_procs_write+0x14/0x20 [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0 [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190 [<ffffffff81265f88>] __vfs_write+0x28/0xe0 [<ffffffff812666fc>] vfs_write+0xac/0x1a0 [<ffffffff81267019>] SyS_write+0x49/0xb0 [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76 This patch fixes the bug by removing @css parameter from the three migration methods, ->can_attach, ->cancel_attach() and ->attach() and updating cgroup_taskset iteration helpers also return the destination css in addition to the task being migrated. All controllers are updated accordingly. * Controllers which don't care whether there are one or multiple target csses can be converted trivially. cpu, io, freezer, perf, netclassid and netprio fall in this category. * cpuset's current implementation assumes that there's single source and destination and thus doesn't support v2 hierarchy already. The only change made by this patchset is how that single destination css is obtained. * memory migration path already doesn't do anything on v2. How the single destination css is obtained is updated and the prep stage of mem_cgroup_can_attach() is reordered to accomodate the change. * pids is the only controller which was affected by this bug. It now correctly handles multi-destination migrations and no longer causes counter underflow from incorrect accounting. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 18:18:21 +03:00
struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset,
struct cgroup_subsys_state **dst_cssp)
{
cgroup: use css_set->mg_tasks to track target tasks during migration Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, this patch updates the migration path to use task->cg_list to track target tasks. The previous patch already added css_set->mg_tasks and updated iterations in non-migration paths to include them during task migration. This patch updates migration path to actually make use of it. Instead of putting onto a flex_array, each target task is moved from its css_set->tasks list to css_set->mg_tasks and the migration path keeps trace of all the source css_sets and the associated cgroups. Once all source css_sets are determined, the destination css_set for each is determined, linked to the matching source css_set and put on a separate list. To iterate the target tasks, migration path just needs to iterat through either the source or target css_sets, depending on whether migration has been committed or not, and the tasks on their ->mg_tasks lists. cgroup_taskset is updated to contain the list_heads for source and target css_sets and the iteration cursor. cgroup_taskset_*() are accordingly updated to walk through css_sets and their ->mg_tasks. This resolves the above listed issues with moderate additional complexity. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node);
tset->cur_task = NULL;
cgroup: fix handling of multi-destination migration from subtree_control enabling Consider the following v2 hierarchy. P0 (+memory) --- P1 (-memory) --- A \- B P0 has memory enabled in its subtree_control while P1 doesn't. If both A and B contain processes, they would belong to the memory css of P1. Now if memory is enabled on P1's subtree_control, memory csses should be created on both A and B and A's processes should be moved to the former and B's processes the latter. IOW, enabling controllers can cause atomic migrations into different csses. The core cgroup migration logic has been updated accordingly but the controller migration methods haven't and still assume that all tasks migrate to a single target css; furthermore, the methods were fed the css in which subtree_control was updated which is the parent of the target csses. pids controller depends on the migration methods to move charges and this made the controller attribute charges to the wrong csses often triggering the following warning by driving a counter negative. WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40() Modules linked in: CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29 ... ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000 ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00 ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8 Call Trace: [<ffffffff81551ffc>] dump_stack+0x4e/0x82 [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0 [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20 [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40 [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0 [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330 [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190 [<ffffffff81189016>] cgroup_attach_task+0x176/0x200 [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460 [<ffffffff81189684>] cgroup_procs_write+0x14/0x20 [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0 [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190 [<ffffffff81265f88>] __vfs_write+0x28/0xe0 [<ffffffff812666fc>] vfs_write+0xac/0x1a0 [<ffffffff81267019>] SyS_write+0x49/0xb0 [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76 This patch fixes the bug by removing @css parameter from the three migration methods, ->can_attach, ->cancel_attach() and ->attach() and updating cgroup_taskset iteration helpers also return the destination css in addition to the task being migrated. All controllers are updated accordingly. * Controllers which don't care whether there are one or multiple target csses can be converted trivially. cpu, io, freezer, perf, netclassid and netprio fall in this category. * cpuset's current implementation assumes that there's single source and destination and thus doesn't support v2 hierarchy already. The only change made by this patchset is how that single destination css is obtained. * memory migration path already doesn't do anything on v2. How the single destination css is obtained is updated and the prep stage of mem_cgroup_can_attach() is reordered to accomodate the change. * pids is the only controller which was affected by this bug. It now correctly handles multi-destination migrations and no longer causes counter underflow from incorrect accounting. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 18:18:21 +03:00
return cgroup_taskset_next(tset, dst_cssp);
}
/**
* cgroup_taskset_next - iterate to the next task in taskset
* @tset: taskset of interest
cgroup: fix handling of multi-destination migration from subtree_control enabling Consider the following v2 hierarchy. P0 (+memory) --- P1 (-memory) --- A \- B P0 has memory enabled in its subtree_control while P1 doesn't. If both A and B contain processes, they would belong to the memory css of P1. Now if memory is enabled on P1's subtree_control, memory csses should be created on both A and B and A's processes should be moved to the former and B's processes the latter. IOW, enabling controllers can cause atomic migrations into different csses. The core cgroup migration logic has been updated accordingly but the controller migration methods haven't and still assume that all tasks migrate to a single target css; furthermore, the methods were fed the css in which subtree_control was updated which is the parent of the target csses. pids controller depends on the migration methods to move charges and this made the controller attribute charges to the wrong csses often triggering the following warning by driving a counter negative. WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40() Modules linked in: CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29 ... ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000 ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00 ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8 Call Trace: [<ffffffff81551ffc>] dump_stack+0x4e/0x82 [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0 [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20 [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40 [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0 [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330 [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190 [<ffffffff81189016>] cgroup_attach_task+0x176/0x200 [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460 [<ffffffff81189684>] cgroup_procs_write+0x14/0x20 [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0 [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190 [<ffffffff81265f88>] __vfs_write+0x28/0xe0 [<ffffffff812666fc>] vfs_write+0xac/0x1a0 [<ffffffff81267019>] SyS_write+0x49/0xb0 [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76 This patch fixes the bug by removing @css parameter from the three migration methods, ->can_attach, ->cancel_attach() and ->attach() and updating cgroup_taskset iteration helpers also return the destination css in addition to the task being migrated. All controllers are updated accordingly. * Controllers which don't care whether there are one or multiple target csses can be converted trivially. cpu, io, freezer, perf, netclassid and netprio fall in this category. * cpuset's current implementation assumes that there's single source and destination and thus doesn't support v2 hierarchy already. The only change made by this patchset is how that single destination css is obtained. * memory migration path already doesn't do anything on v2. How the single destination css is obtained is updated and the prep stage of mem_cgroup_can_attach() is reordered to accomodate the change. * pids is the only controller which was affected by this bug. It now correctly handles multi-destination migrations and no longer causes counter underflow from incorrect accounting. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 18:18:21 +03:00
* @dst_cssp: output variable for the destination css
*
* Return the next task in @tset. Iteration must have been initialized
* with cgroup_taskset_first().
*/
cgroup: fix handling of multi-destination migration from subtree_control enabling Consider the following v2 hierarchy. P0 (+memory) --- P1 (-memory) --- A \- B P0 has memory enabled in its subtree_control while P1 doesn't. If both A and B contain processes, they would belong to the memory css of P1. Now if memory is enabled on P1's subtree_control, memory csses should be created on both A and B and A's processes should be moved to the former and B's processes the latter. IOW, enabling controllers can cause atomic migrations into different csses. The core cgroup migration logic has been updated accordingly but the controller migration methods haven't and still assume that all tasks migrate to a single target css; furthermore, the methods were fed the css in which subtree_control was updated which is the parent of the target csses. pids controller depends on the migration methods to move charges and this made the controller attribute charges to the wrong csses often triggering the following warning by driving a counter negative. WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40() Modules linked in: CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29 ... ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000 ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00 ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8 Call Trace: [<ffffffff81551ffc>] dump_stack+0x4e/0x82 [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0 [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20 [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40 [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0 [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330 [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190 [<ffffffff81189016>] cgroup_attach_task+0x176/0x200 [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460 [<ffffffff81189684>] cgroup_procs_write+0x14/0x20 [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0 [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190 [<ffffffff81265f88>] __vfs_write+0x28/0xe0 [<ffffffff812666fc>] vfs_write+0xac/0x1a0 [<ffffffff81267019>] SyS_write+0x49/0xb0 [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76 This patch fixes the bug by removing @css parameter from the three migration methods, ->can_attach, ->cancel_attach() and ->attach() and updating cgroup_taskset iteration helpers also return the destination css in addition to the task being migrated. All controllers are updated accordingly. * Controllers which don't care whether there are one or multiple target csses can be converted trivially. cpu, io, freezer, perf, netclassid and netprio fall in this category. * cpuset's current implementation assumes that there's single source and destination and thus doesn't support v2 hierarchy already. The only change made by this patchset is how that single destination css is obtained. * memory migration path already doesn't do anything on v2. How the single destination css is obtained is updated and the prep stage of mem_cgroup_can_attach() is reordered to accomodate the change. * pids is the only controller which was affected by this bug. It now correctly handles multi-destination migrations and no longer causes counter underflow from incorrect accounting. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 18:18:21 +03:00
struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
struct cgroup_subsys_state **dst_cssp)
{
cgroup: use css_set->mg_tasks to track target tasks during migration Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, this patch updates the migration path to use task->cg_list to track target tasks. The previous patch already added css_set->mg_tasks and updated iterations in non-migration paths to include them during task migration. This patch updates migration path to actually make use of it. Instead of putting onto a flex_array, each target task is moved from its css_set->tasks list to css_set->mg_tasks and the migration path keeps trace of all the source css_sets and the associated cgroups. Once all source css_sets are determined, the destination css_set for each is determined, linked to the matching source css_set and put on a separate list. To iterate the target tasks, migration path just needs to iterat through either the source or target css_sets, depending on whether migration has been committed or not, and the tasks on their ->mg_tasks lists. cgroup_taskset is updated to contain the list_heads for source and target css_sets and the iteration cursor. cgroup_taskset_*() are accordingly updated to walk through css_sets and their ->mg_tasks. This resolves the above listed issues with moderate additional complexity. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
struct css_set *cset = tset->cur_cset;
struct task_struct *task = tset->cur_task;
cgroup: use css_set->mg_tasks to track target tasks during migration Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, this patch updates the migration path to use task->cg_list to track target tasks. The previous patch already added css_set->mg_tasks and updated iterations in non-migration paths to include them during task migration. This patch updates migration path to actually make use of it. Instead of putting onto a flex_array, each target task is moved from its css_set->tasks list to css_set->mg_tasks and the migration path keeps trace of all the source css_sets and the associated cgroups. Once all source css_sets are determined, the destination css_set for each is determined, linked to the matching source css_set and put on a separate list. To iterate the target tasks, migration path just needs to iterat through either the source or target css_sets, depending on whether migration has been committed or not, and the tasks on their ->mg_tasks lists. cgroup_taskset is updated to contain the list_heads for source and target css_sets and the iteration cursor. cgroup_taskset_*() are accordingly updated to walk through css_sets and their ->mg_tasks. This resolves the above listed issues with moderate additional complexity. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
while (&cset->mg_node != tset->csets) {
if (!task)
task = list_first_entry(&cset->mg_tasks,
struct task_struct, cg_list);
else
task = list_next_entry(task, cg_list);
cgroup: use css_set->mg_tasks to track target tasks during migration Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, this patch updates the migration path to use task->cg_list to track target tasks. The previous patch already added css_set->mg_tasks and updated iterations in non-migration paths to include them during task migration. This patch updates migration path to actually make use of it. Instead of putting onto a flex_array, each target task is moved from its css_set->tasks list to css_set->mg_tasks and the migration path keeps trace of all the source css_sets and the associated cgroups. Once all source css_sets are determined, the destination css_set for each is determined, linked to the matching source css_set and put on a separate list. To iterate the target tasks, migration path just needs to iterat through either the source or target css_sets, depending on whether migration has been committed or not, and the tasks on their ->mg_tasks lists. cgroup_taskset is updated to contain the list_heads for source and target css_sets and the iteration cursor. cgroup_taskset_*() are accordingly updated to walk through css_sets and their ->mg_tasks. This resolves the above listed issues with moderate additional complexity. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
if (&task->cg_list != &cset->mg_tasks) {
tset->cur_cset = cset;
tset->cur_task = task;
cgroup: fix handling of multi-destination migration from subtree_control enabling Consider the following v2 hierarchy. P0 (+memory) --- P1 (-memory) --- A \- B P0 has memory enabled in its subtree_control while P1 doesn't. If both A and B contain processes, they would belong to the memory css of P1. Now if memory is enabled on P1's subtree_control, memory csses should be created on both A and B and A's processes should be moved to the former and B's processes the latter. IOW, enabling controllers can cause atomic migrations into different csses. The core cgroup migration logic has been updated accordingly but the controller migration methods haven't and still assume that all tasks migrate to a single target css; furthermore, the methods were fed the css in which subtree_control was updated which is the parent of the target csses. pids controller depends on the migration methods to move charges and this made the controller attribute charges to the wrong csses often triggering the following warning by driving a counter negative. WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40() Modules linked in: CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29 ... ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000 ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00 ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8 Call Trace: [<ffffffff81551ffc>] dump_stack+0x4e/0x82 [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0 [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20 [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40 [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0 [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330 [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190 [<ffffffff81189016>] cgroup_attach_task+0x176/0x200 [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460 [<ffffffff81189684>] cgroup_procs_write+0x14/0x20 [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0 [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190 [<ffffffff81265f88>] __vfs_write+0x28/0xe0 [<ffffffff812666fc>] vfs_write+0xac/0x1a0 [<ffffffff81267019>] SyS_write+0x49/0xb0 [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76 This patch fixes the bug by removing @css parameter from the three migration methods, ->can_attach, ->cancel_attach() and ->attach() and updating cgroup_taskset iteration helpers also return the destination css in addition to the task being migrated. All controllers are updated accordingly. * Controllers which don't care whether there are one or multiple target csses can be converted trivially. cpu, io, freezer, perf, netclassid and netprio fall in this category. * cpuset's current implementation assumes that there's single source and destination and thus doesn't support v2 hierarchy already. The only change made by this patchset is how that single destination css is obtained. * memory migration path already doesn't do anything on v2. How the single destination css is obtained is updated and the prep stage of mem_cgroup_can_attach() is reordered to accomodate the change. * pids is the only controller which was affected by this bug. It now correctly handles multi-destination migrations and no longer causes counter underflow from incorrect accounting. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 18:18:21 +03:00
/*
* This function may be called both before and
* after cgroup_taskset_migrate(). The two cases
* can be distinguished by looking at whether @cset
* has its ->mg_dst_cset set.
*/
if (cset->mg_dst_cset)
*dst_cssp = cset->mg_dst_cset->subsys[tset->ssid];
else
*dst_cssp = cset->subsys[tset->ssid];
cgroup: use css_set->mg_tasks to track target tasks during migration Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, this patch updates the migration path to use task->cg_list to track target tasks. The previous patch already added css_set->mg_tasks and updated iterations in non-migration paths to include them during task migration. This patch updates migration path to actually make use of it. Instead of putting onto a flex_array, each target task is moved from its css_set->tasks list to css_set->mg_tasks and the migration path keeps trace of all the source css_sets and the associated cgroups. Once all source css_sets are determined, the destination css_set for each is determined, linked to the matching source css_set and put on a separate list. To iterate the target tasks, migration path just needs to iterat through either the source or target css_sets, depending on whether migration has been committed or not, and the tasks on their ->mg_tasks lists. cgroup_taskset is updated to contain the list_heads for source and target css_sets and the iteration cursor. cgroup_taskset_*() are accordingly updated to walk through css_sets and their ->mg_tasks. This resolves the above listed issues with moderate additional complexity. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
return task;
}
cgroup: use css_set->mg_tasks to track target tasks during migration Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, this patch updates the migration path to use task->cg_list to track target tasks. The previous patch already added css_set->mg_tasks and updated iterations in non-migration paths to include them during task migration. This patch updates migration path to actually make use of it. Instead of putting onto a flex_array, each target task is moved from its css_set->tasks list to css_set->mg_tasks and the migration path keeps trace of all the source css_sets and the associated cgroups. Once all source css_sets are determined, the destination css_set for each is determined, linked to the matching source css_set and put on a separate list. To iterate the target tasks, migration path just needs to iterat through either the source or target css_sets, depending on whether migration has been committed or not, and the tasks on their ->mg_tasks lists. cgroup_taskset is updated to contain the list_heads for source and target css_sets and the iteration cursor. cgroup_taskset_*() are accordingly updated to walk through css_sets and their ->mg_tasks. This resolves the above listed issues with moderate additional complexity. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
cset = list_next_entry(cset, mg_node);
task = NULL;
}
cgroup: use css_set->mg_tasks to track target tasks during migration Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, this patch updates the migration path to use task->cg_list to track target tasks. The previous patch already added css_set->mg_tasks and updated iterations in non-migration paths to include them during task migration. This patch updates migration path to actually make use of it. Instead of putting onto a flex_array, each target task is moved from its css_set->tasks list to css_set->mg_tasks and the migration path keeps trace of all the source css_sets and the associated cgroups. Once all source css_sets are determined, the destination css_set for each is determined, linked to the matching source css_set and put on a separate list. To iterate the target tasks, migration path just needs to iterat through either the source or target css_sets, depending on whether migration has been committed or not, and the tasks on their ->mg_tasks lists. cgroup_taskset is updated to contain the list_heads for source and target css_sets and the iteration cursor. cgroup_taskset_*() are accordingly updated to walk through css_sets and their ->mg_tasks. This resolves the above listed issues with moderate additional complexity. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
return NULL;
}
/**
* cgroup_taskset_migrate - migrate a taskset to a cgroup
* @tset: taget taskset
* @dst_cgrp: destination cgroup
*
* Migrate tasks in @tset to @dst_cgrp. This function fails iff one of the
* ->can_attach callbacks fails and guarantees that either all or none of
* the tasks in @tset are migrated. @tset is consumed regardless of
* success.
*/
static int cgroup_taskset_migrate(struct cgroup_taskset *tset,
struct cgroup *dst_cgrp)
{
struct cgroup_subsys_state *css, *failed_css = NULL;
struct task_struct *task, *tmp_task;
struct css_set *cset, *tmp_cset;
int i, ret;
/* methods shouldn't be called if no task is actually migrating */
if (list_empty(&tset->src_csets))
return 0;
/* check that we can legitimately attach to the cgroup */
for_each_e_css(css, i, dst_cgrp) {
if (css->ss->can_attach) {
cgroup: fix handling of multi-destination migration from subtree_control enabling Consider the following v2 hierarchy. P0 (+memory) --- P1 (-memory) --- A \- B P0 has memory enabled in its subtree_control while P1 doesn't. If both A and B contain processes, they would belong to the memory css of P1. Now if memory is enabled on P1's subtree_control, memory csses should be created on both A and B and A's processes should be moved to the former and B's processes the latter. IOW, enabling controllers can cause atomic migrations into different csses. The core cgroup migration logic has been updated accordingly but the controller migration methods haven't and still assume that all tasks migrate to a single target css; furthermore, the methods were fed the css in which subtree_control was updated which is the parent of the target csses. pids controller depends on the migration methods to move charges and this made the controller attribute charges to the wrong csses often triggering the following warning by driving a counter negative. WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40() Modules linked in: CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29 ... ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000 ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00 ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8 Call Trace: [<ffffffff81551ffc>] dump_stack+0x4e/0x82 [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0 [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20 [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40 [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0 [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330 [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190 [<ffffffff81189016>] cgroup_attach_task+0x176/0x200 [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460 [<ffffffff81189684>] cgroup_procs_write+0x14/0x20 [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0 [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190 [<ffffffff81265f88>] __vfs_write+0x28/0xe0 [<ffffffff812666fc>] vfs_write+0xac/0x1a0 [<ffffffff81267019>] SyS_write+0x49/0xb0 [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76 This patch fixes the bug by removing @css parameter from the three migration methods, ->can_attach, ->cancel_attach() and ->attach() and updating cgroup_taskset iteration helpers also return the destination css in addition to the task being migrated. All controllers are updated accordingly. * Controllers which don't care whether there are one or multiple target csses can be converted trivially. cpu, io, freezer, perf, netclassid and netprio fall in this category. * cpuset's current implementation assumes that there's single source and destination and thus doesn't support v2 hierarchy already. The only change made by this patchset is how that single destination css is obtained. * memory migration path already doesn't do anything on v2. How the single destination css is obtained is updated and the prep stage of mem_cgroup_can_attach() is reordered to accomodate the change. * pids is the only controller which was affected by this bug. It now correctly handles multi-destination migrations and no longer causes counter underflow from incorrect accounting. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 18:18:21 +03:00
tset->ssid = i;
ret = css->ss->can_attach(tset);
if (ret) {
failed_css = css;
goto out_cancel_attach;
}
}
}
/*
* Now that we're guaranteed success, proceed to move all tasks to
* the new cgroup. There are no failure cases after here, so this
* is the commit point.
*/
spin_lock_bh(&css_set_lock);
list_for_each_entry(cset, &tset->src_csets, mg_node) {
list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) {
struct css_set *from_cset = task_css_set(task);
struct css_set *to_cset = cset->mg_dst_cset;
get_css_set(to_cset);
css_set_move_task(task, from_cset, to_cset, true);
put_css_set_locked(from_cset);
}
}
spin_unlock_bh(&css_set_lock);
/*
* Migration is committed, all target tasks are now on dst_csets.
* Nothing is sensitive to fork() after this point. Notify
* controllers that migration is complete.
*/
tset->csets = &tset->dst_csets;
cgroup: fix handling of multi-destination migration from subtree_control enabling Consider the following v2 hierarchy. P0 (+memory) --- P1 (-memory) --- A \- B P0 has memory enabled in its subtree_control while P1 doesn't. If both A and B contain processes, they would belong to the memory css of P1. Now if memory is enabled on P1's subtree_control, memory csses should be created on both A and B and A's processes should be moved to the former and B's processes the latter. IOW, enabling controllers can cause atomic migrations into different csses. The core cgroup migration logic has been updated accordingly but the controller migration methods haven't and still assume that all tasks migrate to a single target css; furthermore, the methods were fed the css in which subtree_control was updated which is the parent of the target csses. pids controller depends on the migration methods to move charges and this made the controller attribute charges to the wrong csses often triggering the following warning by driving a counter negative. WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40() Modules linked in: CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29 ... ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000 ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00 ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8 Call Trace: [<ffffffff81551ffc>] dump_stack+0x4e/0x82 [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0 [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20 [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40 [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0 [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330 [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190 [<ffffffff81189016>] cgroup_attach_task+0x176/0x200 [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460 [<ffffffff81189684>] cgroup_procs_write+0x14/0x20 [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0 [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190 [<ffffffff81265f88>] __vfs_write+0x28/0xe0 [<ffffffff812666fc>] vfs_write+0xac/0x1a0 [<ffffffff81267019>] SyS_write+0x49/0xb0 [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76 This patch fixes the bug by removing @css parameter from the three migration methods, ->can_attach, ->cancel_attach() and ->attach() and updating cgroup_taskset iteration helpers also return the destination css in addition to the task being migrated. All controllers are updated accordingly. * Controllers which don't care whether there are one or multiple target csses can be converted trivially. cpu, io, freezer, perf, netclassid and netprio fall in this category. * cpuset's current implementation assumes that there's single source and destination and thus doesn't support v2 hierarchy already. The only change made by this patchset is how that single destination css is obtained. * memory migration path already doesn't do anything on v2. How the single destination css is obtained is updated and the prep stage of mem_cgroup_can_attach() is reordered to accomodate the change. * pids is the only controller which was affected by this bug. It now correctly handles multi-destination migrations and no longer causes counter underflow from incorrect accounting. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 18:18:21 +03:00
for_each_e_css(css, i, dst_cgrp) {
if (css->ss->attach) {
tset->ssid = i;
css->ss->attach(tset);
}
}
ret = 0;
goto out_release_tset;
out_cancel_attach:
for_each_e_css(css, i, dst_cgrp) {
if (css == failed_css)
break;
cgroup: fix handling of multi-destination migration from subtree_control enabling Consider the following v2 hierarchy. P0 (+memory) --- P1 (-memory) --- A \- B P0 has memory enabled in its subtree_control while P1 doesn't. If both A and B contain processes, they would belong to the memory css of P1. Now if memory is enabled on P1's subtree_control, memory csses should be created on both A and B and A's processes should be moved to the former and B's processes the latter. IOW, enabling controllers can cause atomic migrations into different csses. The core cgroup migration logic has been updated accordingly but the controller migration methods haven't and still assume that all tasks migrate to a single target css; furthermore, the methods were fed the css in which subtree_control was updated which is the parent of the target csses. pids controller depends on the migration methods to move charges and this made the controller attribute charges to the wrong csses often triggering the following warning by driving a counter negative. WARNING: CPU: 1 PID: 1 at kernel/cgroup_pids.c:97 pids_cancel.constprop.6+0x31/0x40() Modules linked in: CPU: 1 PID: 1 Comm: systemd Not tainted 4.4.0-rc1+ #29 ... ffffffff81f65382 ffff88007c043b90 ffffffff81551ffc 0000000000000000 ffff88007c043bc8 ffffffff810de202 ffff88007a752000 ffff88007a29ab00 ffff88007c043c80 ffff88007a1d8400 0000000000000001 ffff88007c043bd8 Call Trace: [<ffffffff81551ffc>] dump_stack+0x4e/0x82 [<ffffffff810de202>] warn_slowpath_common+0x82/0xc0 [<ffffffff810de2fa>] warn_slowpath_null+0x1a/0x20 [<ffffffff8118e031>] pids_cancel.constprop.6+0x31/0x40 [<ffffffff8118e0fd>] pids_can_attach+0x6d/0xf0 [<ffffffff81188a4c>] cgroup_taskset_migrate+0x6c/0x330 [<ffffffff81188e05>] cgroup_migrate+0xf5/0x190 [<ffffffff81189016>] cgroup_attach_task+0x176/0x200 [<ffffffff8118949d>] __cgroup_procs_write+0x2ad/0x460 [<ffffffff81189684>] cgroup_procs_write+0x14/0x20 [<ffffffff811854e5>] cgroup_file_write+0x35/0x1c0 [<ffffffff812e26f1>] kernfs_fop_write+0x141/0x190 [<ffffffff81265f88>] __vfs_write+0x28/0xe0 [<ffffffff812666fc>] vfs_write+0xac/0x1a0 [<ffffffff81267019>] SyS_write+0x49/0xb0 [<ffffffff81bcef32>] entry_SYSCALL_64_fastpath+0x12/0x76 This patch fixes the bug by removing @css parameter from the three migration methods, ->can_attach, ->cancel_attach() and ->attach() and updating cgroup_taskset iteration helpers also return the destination css in addition to the task being migrated. All controllers are updated accordingly. * Controllers which don't care whether there are one or multiple target csses can be converted trivially. cpu, io, freezer, perf, netclassid and netprio fall in this category. * cpuset's current implementation assumes that there's single source and destination and thus doesn't support v2 hierarchy already. The only change made by this patchset is how that single destination css is obtained. * memory migration path already doesn't do anything on v2. How the single destination css is obtained is updated and the prep stage of mem_cgroup_can_attach() is reordered to accomodate the change. * pids is the only controller which was affected by this bug. It now correctly handles multi-destination migrations and no longer causes counter underflow from incorrect accounting. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Aleksa Sarai <cyphar@cyphar.com>
2015-12-03 18:18:21 +03:00
if (css->ss->cancel_attach) {
tset->ssid = i;
css->ss->cancel_attach(tset);
}
}
out_release_tset:
spin_lock_bh(&css_set_lock);
list_splice_init(&tset->dst_csets, &tset->src_csets);
list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) {
list_splice_tail_init(&cset->mg_tasks, &cset->tasks);
list_del_init(&cset->mg_node);
}
spin_unlock_bh(&css_set_lock);
return ret;
}
/**
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
* cgroup_migrate_finish - cleanup after attach
* @preloaded_csets: list of preloaded css_sets
*
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
* Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
* those functions for details.
*/
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
static void cgroup_migrate_finish(struct list_head *preloaded_csets)
{
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
struct css_set *cset, *tmp_cset;
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
lockdep_assert_held(&cgroup_mutex);
spin_lock_bh(&css_set_lock);
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) {
cset->mg_src_cgrp = NULL;
cset->mg_dst_cset = NULL;
list_del_init(&cset->mg_preload_node);
put_css_set_locked(cset);
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
}
spin_unlock_bh(&css_set_lock);
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
}
/**
* cgroup_migrate_add_src - add a migration source css_set
* @src_cset: the source css_set to add
* @dst_cgrp: the destination cgroup
* @preloaded_csets: list of preloaded css_sets
*
* Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
* @src_cset and add it to @preloaded_csets, which should later be cleaned
* up by cgroup_migrate_finish().
*
* This function may be called without holding cgroup_threadgroup_rwsem
* even if the target is a process. Threads may be created and destroyed
* but as long as cgroup_mutex is not dropped, no new css_set can be put
* into play and the preloaded css_sets are guaranteed to cover all
* migrations.
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
*/
static void cgroup_migrate_add_src(struct css_set *src_cset,
struct cgroup *dst_cgrp,
struct list_head *preloaded_csets)
{
struct cgroup *src_cgrp;
lockdep_assert_held(&cgroup_mutex);
lockdep_assert_held(&css_set_lock);
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
if (!list_empty(&src_cset->mg_preload_node))
return;
WARN_ON(src_cset->mg_src_cgrp);
WARN_ON(!list_empty(&src_cset->mg_tasks));
WARN_ON(!list_empty(&src_cset->mg_node));
src_cset->mg_src_cgrp = src_cgrp;
get_css_set(src_cset);
list_add(&src_cset->mg_preload_node, preloaded_csets);
}
/**
* cgroup_migrate_prepare_dst - prepare destination css_sets for migration
* @dst_cgrp: the destination cgroup (may be %NULL)
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
* @preloaded_csets: list of preloaded source css_sets
*
* Tasks are about to be moved to @dst_cgrp and all the source css_sets
* have been preloaded to @preloaded_csets. This function looks up and
* pins all destination css_sets, links each to its source, and append them
* to @preloaded_csets. If @dst_cgrp is %NULL, the destination of each
* source css_set is assumed to be its cgroup on the default hierarchy.
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
*
* This function must be called after cgroup_migrate_add_src() has been
* called on each migration source css_set. After migration is performed
* using cgroup_migrate(), cgroup_migrate_finish() must be called on
* @preloaded_csets.
*/
static int cgroup_migrate_prepare_dst(struct cgroup *dst_cgrp,
struct list_head *preloaded_csets)
{
LIST_HEAD(csets);
struct css_set *src_cset, *tmp_cset;
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
lockdep_assert_held(&cgroup_mutex);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
/*
* Except for the root, subtree_control must be zero for a cgroup
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
* with tasks so that child cgroups don't compete against tasks.
*/
if (dst_cgrp && cgroup_on_dfl(dst_cgrp) && cgroup_parent(dst_cgrp) &&
dst_cgrp->subtree_control)
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
return -EBUSY;
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
/* look up the dst cset for each src cset and link it to src */
list_for_each_entry_safe(src_cset, tmp_cset, preloaded_csets, mg_preload_node) {
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
struct css_set *dst_cset;
dst_cset = find_css_set(src_cset,
dst_cgrp ?: src_cset->dfl_cgrp);
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
if (!dst_cset)
goto err;
WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset);
/*
* If src cset equals dst, it's noop. Drop the src.
* cgroup_migrate() will skip the cset too. Note that we
* can't handle src == dst as some nodes are used by both.
*/
if (src_cset == dst_cset) {
src_cset->mg_src_cgrp = NULL;
list_del_init(&src_cset->mg_preload_node);
put_css_set(src_cset);
put_css_set(dst_cset);
continue;
}
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
src_cset->mg_dst_cset = dst_cset;
if (list_empty(&dst_cset->mg_preload_node))
list_add(&dst_cset->mg_preload_node, &csets);
else
put_css_set(dst_cset);
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
}
list_splice_tail(&csets, preloaded_csets);
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
return 0;
err:
cgroup_migrate_finish(&csets);
return -ENOMEM;
}
/**
* cgroup_migrate - migrate a process or task to a cgroup
* @leader: the leader of the process or the task to migrate
* @threadgroup: whether @leader points to the whole process or a single task
* @cgrp: the destination cgroup
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
*
* Migrate a process or task denoted by @leader to @cgrp. If migrating a
* process, the caller must be holding cgroup_threadgroup_rwsem. The
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
* caller is also responsible for invoking cgroup_migrate_add_src() and
* cgroup_migrate_prepare_dst() on the targets before invoking this
* function and following up with cgroup_migrate_finish().
*
* As long as a controller's ->can_attach() doesn't fail, this function is
* guaranteed to succeed. This means that, excluding ->can_attach()
* failure, when migrating multiple targets, the success or failure can be
* decided for all targets by invoking group_migrate_prepare_dst() before
* actually starting migrating.
*/
static int cgroup_migrate(struct task_struct *leader, bool threadgroup,
struct cgroup *cgrp)
{
struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset);
struct task_struct *task;
/*
* Prevent freeing of tasks while we take a snapshot. Tasks that are
* already PF_EXITING could be freed from underneath us unless we
* take an rcu_read_lock.
*/
spin_lock_bh(&css_set_lock);
rcu_read_lock();
task = leader;
do {
cgroup_taskset_add(task, &tset);
if (!threadgroup)
break;
} while_each_thread(leader, task);
rcu_read_unlock();
spin_unlock_bh(&css_set_lock);
return cgroup_taskset_migrate(&tset, cgrp);
}
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
/**
* cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
* @dst_cgrp: the cgroup to attach to
* @leader: the task or the leader of the threadgroup to be attached
* @threadgroup: attach the whole threadgroup?
*
* Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
*/
static int cgroup_attach_task(struct cgroup *dst_cgrp,
struct task_struct *leader, bool threadgroup)
{
LIST_HEAD(preloaded_csets);
struct task_struct *task;
int ret;
/* look up all src csets */
spin_lock_bh(&css_set_lock);
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
rcu_read_lock();
task = leader;
do {
cgroup_migrate_add_src(task_css_set(task), dst_cgrp,
&preloaded_csets);
if (!threadgroup)
break;
} while_each_thread(leader, task);
rcu_read_unlock();
spin_unlock_bh(&css_set_lock);
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
/* prepare dst csets and commit */
ret = cgroup_migrate_prepare_dst(dst_cgrp, &preloaded_csets);
if (!ret)
ret = cgroup_migrate(leader, threadgroup, dst_cgrp);
cgroup: split process / task migration into four steps Currently, process / task migration is a single operation which may fail depending on memory pressure or the involved controllers' ->can_attach() callbacks. One problem with this approach is migration of multiple targets. It's impossible to tell whether a given target will be successfully migrated beforehand and cgroup core can't keep track of enough states to roll back after intermediate failure. This is already an issue with cgroup_transfer_tasks(). Also, we're gonna need multiple target migration for unified hierarchy. This patch splits migration into four stages - cgroup_migrate_add_src(), cgroup_migrate_prepare_dst(), cgroup_migrate() and cgroup_migrate_finish(), where cgroup_migrate_prepare_dst() performs all the operations which may fail due to allocation failure without actually migrating the target. The four separate stages mean that, disregarding ->can_attach() failures, the success or failure of multi target migration can be determined before performing any actual migration. If preparations of all targets succeed, the whole thing will succeed. If not, the whole operation can fail without any side-effect. Since the previous patch to use css_set->mg_tasks to keep track of migration targets, the only thing which may need memory allocation during migration is the target css_sets. cgroup_migrate_prepare() pins all source and target css_sets and link them up. Note that this can be performed without holding threadgroup_lock even if the target is a process. As long as cgroup_mutex is held, no new css_set can be put into play. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
cgroup_migrate_finish(&preloaded_csets);
return ret;
}
cgroup: require write perm on common ancestor when moving processes on the default hierarchy On traditional hierarchies, if a task has write access to "tasks" or "cgroup.procs" file of a cgroup and its euid agrees with the target, it can move the target to the cgroup; however, consider the following scenario. The owner of each cgroup is in the parentheses. R (root) - 0 (root) - 00 (user1) - 000 (user1) | \ 001 (user1) \ 1 (root) - 10 (user1) The subtrees of 00 and 10 are delegated to user1; however, while both subtrees may belong to the same user, it is clear that the two subtrees are to be isolated - they're under completely separate resource limits imposed by 0 and 1, respectively. Note that 0 and 1 aren't strictly necessary but added to ease illustrating the issue. If user1 is allowed to move processes between the two subtrees, the intention of the hierarchy - keeping a given group of processes under a subtree with certain resource restrictions while delegating management of the subtree - can be circumvented by user1. This happens because migration permission check doesn't consider the hierarchical nature of cgroups. To fix the issue, this patch adds an extra permission requirement when userland tries to migrate a process in the default hierarchy - the issuing task must have write access to the common ancestor of "cgroup.procs" file of the ancestor in addition to the destination's. Conceptually, the issuer must be able to move the target process from the source cgroup to the common ancestor of source and destination cgroups and then to the destination. As long as delegation is done in a proper top-down way, this guarantees that a delegatee can't smuggle processes across disjoint delegation domains. The next patch will add documentation on the delegation model on the default hierarchy. v2: Fixed missing !ret test. Spotted by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com>
2015-06-18 23:54:28 +03:00
static int cgroup_procs_write_permission(struct task_struct *task,
struct cgroup *dst_cgrp,
struct kernfs_open_file *of)
{
const struct cred *cred = current_cred();
const struct cred *tcred = get_task_cred(task);
int ret = 0;
/*
* even if we're attaching all tasks in the thread group, we only
* need to check permissions on one of them.
*/
if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
!uid_eq(cred->euid, tcred->uid) &&
!uid_eq(cred->euid, tcred->suid))
ret = -EACCES;
cgroup: require write perm on common ancestor when moving processes on the default hierarchy On traditional hierarchies, if a task has write access to "tasks" or "cgroup.procs" file of a cgroup and its euid agrees with the target, it can move the target to the cgroup; however, consider the following scenario. The owner of each cgroup is in the parentheses. R (root) - 0 (root) - 00 (user1) - 000 (user1) | \ 001 (user1) \ 1 (root) - 10 (user1) The subtrees of 00 and 10 are delegated to user1; however, while both subtrees may belong to the same user, it is clear that the two subtrees are to be isolated - they're under completely separate resource limits imposed by 0 and 1, respectively. Note that 0 and 1 aren't strictly necessary but added to ease illustrating the issue. If user1 is allowed to move processes between the two subtrees, the intention of the hierarchy - keeping a given group of processes under a subtree with certain resource restrictions while delegating management of the subtree - can be circumvented by user1. This happens because migration permission check doesn't consider the hierarchical nature of cgroups. To fix the issue, this patch adds an extra permission requirement when userland tries to migrate a process in the default hierarchy - the issuing task must have write access to the common ancestor of "cgroup.procs" file of the ancestor in addition to the destination's. Conceptually, the issuer must be able to move the target process from the source cgroup to the common ancestor of source and destination cgroups and then to the destination. As long as delegation is done in a proper top-down way, this guarantees that a delegatee can't smuggle processes across disjoint delegation domains. The next patch will add documentation on the delegation model on the default hierarchy. v2: Fixed missing !ret test. Spotted by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com>
2015-06-18 23:54:28 +03:00
if (!ret && cgroup_on_dfl(dst_cgrp)) {
struct super_block *sb = of->file->f_path.dentry->d_sb;
struct cgroup *cgrp;
struct inode *inode;
spin_lock_bh(&css_set_lock);
cgroup: require write perm on common ancestor when moving processes on the default hierarchy On traditional hierarchies, if a task has write access to "tasks" or "cgroup.procs" file of a cgroup and its euid agrees with the target, it can move the target to the cgroup; however, consider the following scenario. The owner of each cgroup is in the parentheses. R (root) - 0 (root) - 00 (user1) - 000 (user1) | \ 001 (user1) \ 1 (root) - 10 (user1) The subtrees of 00 and 10 are delegated to user1; however, while both subtrees may belong to the same user, it is clear that the two subtrees are to be isolated - they're under completely separate resource limits imposed by 0 and 1, respectively. Note that 0 and 1 aren't strictly necessary but added to ease illustrating the issue. If user1 is allowed to move processes between the two subtrees, the intention of the hierarchy - keeping a given group of processes under a subtree with certain resource restrictions while delegating management of the subtree - can be circumvented by user1. This happens because migration permission check doesn't consider the hierarchical nature of cgroups. To fix the issue, this patch adds an extra permission requirement when userland tries to migrate a process in the default hierarchy - the issuing task must have write access to the common ancestor of "cgroup.procs" file of the ancestor in addition to the destination's. Conceptually, the issuer must be able to move the target process from the source cgroup to the common ancestor of source and destination cgroups and then to the destination. As long as delegation is done in a proper top-down way, this guarantees that a delegatee can't smuggle processes across disjoint delegation domains. The next patch will add documentation on the delegation model on the default hierarchy. v2: Fixed missing !ret test. Spotted by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com>
2015-06-18 23:54:28 +03:00
cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
spin_unlock_bh(&css_set_lock);
cgroup: require write perm on common ancestor when moving processes on the default hierarchy On traditional hierarchies, if a task has write access to "tasks" or "cgroup.procs" file of a cgroup and its euid agrees with the target, it can move the target to the cgroup; however, consider the following scenario. The owner of each cgroup is in the parentheses. R (root) - 0 (root) - 00 (user1) - 000 (user1) | \ 001 (user1) \ 1 (root) - 10 (user1) The subtrees of 00 and 10 are delegated to user1; however, while both subtrees may belong to the same user, it is clear that the two subtrees are to be isolated - they're under completely separate resource limits imposed by 0 and 1, respectively. Note that 0 and 1 aren't strictly necessary but added to ease illustrating the issue. If user1 is allowed to move processes between the two subtrees, the intention of the hierarchy - keeping a given group of processes under a subtree with certain resource restrictions while delegating management of the subtree - can be circumvented by user1. This happens because migration permission check doesn't consider the hierarchical nature of cgroups. To fix the issue, this patch adds an extra permission requirement when userland tries to migrate a process in the default hierarchy - the issuing task must have write access to the common ancestor of "cgroup.procs" file of the ancestor in addition to the destination's. Conceptually, the issuer must be able to move the target process from the source cgroup to the common ancestor of source and destination cgroups and then to the destination. As long as delegation is done in a proper top-down way, this guarantees that a delegatee can't smuggle processes across disjoint delegation domains. The next patch will add documentation on the delegation model on the default hierarchy. v2: Fixed missing !ret test. Spotted by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com>
2015-06-18 23:54:28 +03:00
while (!cgroup_is_descendant(dst_cgrp, cgrp))
cgrp = cgroup_parent(cgrp);
ret = -ENOMEM;
inode = kernfs_get_inode(sb, cgrp->procs_file.kn);
cgroup: require write perm on common ancestor when moving processes on the default hierarchy On traditional hierarchies, if a task has write access to "tasks" or "cgroup.procs" file of a cgroup and its euid agrees with the target, it can move the target to the cgroup; however, consider the following scenario. The owner of each cgroup is in the parentheses. R (root) - 0 (root) - 00 (user1) - 000 (user1) | \ 001 (user1) \ 1 (root) - 10 (user1) The subtrees of 00 and 10 are delegated to user1; however, while both subtrees may belong to the same user, it is clear that the two subtrees are to be isolated - they're under completely separate resource limits imposed by 0 and 1, respectively. Note that 0 and 1 aren't strictly necessary but added to ease illustrating the issue. If user1 is allowed to move processes between the two subtrees, the intention of the hierarchy - keeping a given group of processes under a subtree with certain resource restrictions while delegating management of the subtree - can be circumvented by user1. This happens because migration permission check doesn't consider the hierarchical nature of cgroups. To fix the issue, this patch adds an extra permission requirement when userland tries to migrate a process in the default hierarchy - the issuing task must have write access to the common ancestor of "cgroup.procs" file of the ancestor in addition to the destination's. Conceptually, the issuer must be able to move the target process from the source cgroup to the common ancestor of source and destination cgroups and then to the destination. As long as delegation is done in a proper top-down way, this guarantees that a delegatee can't smuggle processes across disjoint delegation domains. The next patch will add documentation on the delegation model on the default hierarchy. v2: Fixed missing !ret test. Spotted by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com>
2015-06-18 23:54:28 +03:00
if (inode) {
ret = inode_permission(inode, MAY_WRITE);
iput(inode);
}
}
put_cred(tcred);
return ret;
}
/*
* Find the task_struct of the task to attach by vpid and pass it along to the
cgroup: always lock threadgroup during migration Update cgroup to take advantage of the fack that threadgroup_lock() guarantees stable threadgroup. * Lock threadgroup even if the target is a single task. This guarantees that when the target tasks stay stable during migration regardless of the target type. * Remove PF_EXITING early exit optimization from attach_task_by_pid() and check it in cgroup_task_migrate() instead. The optimization was for rather cold path to begin with and PF_EXITING state can be trusted throughout migration by checking it after locking threadgroup. * Don't add PF_EXITING tasks to target task array in cgroup_attach_proc(). This ensures that task migration is performed only for live tasks. * Remove -ESRCH failure path from cgroup_task_migrate(). With the above changes, it's guaranteed to be called only for live tasks. After the changes, only live tasks are migrated and they're guaranteed to stay alive until migration is complete. This removes problems caused by exec and exit racing against cgroup migration including symmetry among cgroup attach methods and different cgroup methods racing each other. v2: Oleg pointed out that one more PF_EXITING check can be removed from cgroup_attach_proc(). Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Paul Menage <paul@paulmenage.org>
2011-12-13 06:12:21 +04:00
* function to attach either it or all tasks in its threadgroup. Will lock
* cgroup_mutex and threadgroup.
*/
static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
size_t nbytes, loff_t off, bool threadgroup)
{
struct task_struct *tsk;
struct cgroup *cgrp;
pid_t pid;
int ret;
if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
return -EINVAL;
cgrp = cgroup_kn_lock_live(of->kn);
if (!cgrp)
return -ENODEV;
percpu_down_write(&cgroup_threadgroup_rwsem);
rcu_read_lock();
if (pid) {
tsk = find_task_by_vpid(pid);
if (!tsk) {
ret = -ESRCH;
goto out_unlock_rcu;
}
} else {
tsk = current;
}
cgroup: always lock threadgroup during migration Update cgroup to take advantage of the fack that threadgroup_lock() guarantees stable threadgroup. * Lock threadgroup even if the target is a single task. This guarantees that when the target tasks stay stable during migration regardless of the target type. * Remove PF_EXITING early exit optimization from attach_task_by_pid() and check it in cgroup_task_migrate() instead. The optimization was for rather cold path to begin with and PF_EXITING state can be trusted throughout migration by checking it after locking threadgroup. * Don't add PF_EXITING tasks to target task array in cgroup_attach_proc(). This ensures that task migration is performed only for live tasks. * Remove -ESRCH failure path from cgroup_task_migrate(). With the above changes, it's guaranteed to be called only for live tasks. After the changes, only live tasks are migrated and they're guaranteed to stay alive until migration is complete. This removes problems caused by exec and exit racing against cgroup migration including symmetry among cgroup attach methods and different cgroup methods racing each other. v2: Oleg pointed out that one more PF_EXITING check can be removed from cgroup_attach_proc(). Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Paul Menage <paul@paulmenage.org>
2011-12-13 06:12:21 +04:00
if (threadgroup)
tsk = tsk->group_leader;
/*
* Workqueue threads may acquire PF_NO_SETAFFINITY and become
* trapped in a cpuset, or RT worker may be born in a cgroup
* with no rt_runtime allocated. Just say no.
*/
if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) {
ret = -EINVAL;
goto out_unlock_rcu;
}
get_task_struct(tsk);
rcu_read_unlock();
cgroup: require write perm on common ancestor when moving processes on the default hierarchy On traditional hierarchies, if a task has write access to "tasks" or "cgroup.procs" file of a cgroup and its euid agrees with the target, it can move the target to the cgroup; however, consider the following scenario. The owner of each cgroup is in the parentheses. R (root) - 0 (root) - 00 (user1) - 000 (user1) | \ 001 (user1) \ 1 (root) - 10 (user1) The subtrees of 00 and 10 are delegated to user1; however, while both subtrees may belong to the same user, it is clear that the two subtrees are to be isolated - they're under completely separate resource limits imposed by 0 and 1, respectively. Note that 0 and 1 aren't strictly necessary but added to ease illustrating the issue. If user1 is allowed to move processes between the two subtrees, the intention of the hierarchy - keeping a given group of processes under a subtree with certain resource restrictions while delegating management of the subtree - can be circumvented by user1. This happens because migration permission check doesn't consider the hierarchical nature of cgroups. To fix the issue, this patch adds an extra permission requirement when userland tries to migrate a process in the default hierarchy - the issuing task must have write access to the common ancestor of "cgroup.procs" file of the ancestor in addition to the destination's. Conceptually, the issuer must be able to move the target process from the source cgroup to the common ancestor of source and destination cgroups and then to the destination. As long as delegation is done in a proper top-down way, this guarantees that a delegatee can't smuggle processes across disjoint delegation domains. The next patch will add documentation on the delegation model on the default hierarchy. v2: Fixed missing !ret test. Spotted by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Li Zefan <lizefan@huawei.com>
2015-06-18 23:54:28 +03:00
ret = cgroup_procs_write_permission(tsk, cgrp, of);
if (!ret)
ret = cgroup_attach_task(cgrp, tsk, threadgroup);
put_task_struct(tsk);
goto out_unlock_threadgroup;
out_unlock_rcu:
rcu_read_unlock();
out_unlock_threadgroup:
percpu_up_write(&cgroup_threadgroup_rwsem);
cgroup_kn_unlock(of->kn);
cpuset_post_attach_flush();
return ret ?: nbytes;
}
/**
* cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
* @from: attach to all cgroups of a given task
* @tsk: the task to be attached
*/
int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
{
struct cgroup_root *root;
int retval = 0;
mutex_lock(&cgroup_mutex);
for_each_root(root) {
2014-02-13 15:58:40 +04:00
struct cgroup *from_cgrp;
if (root == &cgrp_dfl_root)
continue;
spin_lock_bh(&css_set_lock);
2014-02-13 15:58:40 +04:00
from_cgrp = task_cgroup_from_root(from, root);
spin_unlock_bh(&css_set_lock);
retval = cgroup_attach_task(from_cgrp, tsk, false);
if (retval)
break;
}
mutex_unlock(&cgroup_mutex);
return retval;
}
EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
static ssize_t cgroup_tasks_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
return __cgroup_procs_write(of, buf, nbytes, off, false);
}
static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
return __cgroup_procs_write(of, buf, nbytes, off, true);
}
static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct cgroup *cgrp;
BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
cgrp = cgroup_kn_lock_live(of->kn);
if (!cgrp)
return -ENODEV;
spin_lock(&release_agent_path_lock);
strlcpy(cgrp->root->release_agent_path, strstrip(buf),
sizeof(cgrp->root->release_agent_path));
spin_unlock(&release_agent_path_lock);
cgroup_kn_unlock(of->kn);
return nbytes;
}
static int cgroup_release_agent_show(struct seq_file *seq, void *v)
{
struct cgroup *cgrp = seq_css(seq)->cgroup;
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
spin_lock(&release_agent_path_lock);
seq_puts(seq, cgrp->root->release_agent_path);
spin_unlock(&release_agent_path_lock);
seq_putc(seq, '\n');
return 0;
}
static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
cgroup: introduce sane_behavior mount option It's a sad fact that at this point various cgroup controllers are carrying so many idiosyncrasies and pure insanities that it simply isn't possible to reach any sort of sane consistent behavior while maintaining staying fully compatible with what already has been exposed to userland. As we can't break exposed userland interface, transitioning to sane behaviors can only be done in steps while maintaining backwards compatibility. This patch introduces a new mount option - __DEVEL__sane_behavior - which disables crazy features and enforces consistent behaviors in cgroup core proper and various controllers. As exactly which behaviors it changes are still being determined, the mount option, at this point, is useful only for development of the new behaviors. As such, the mount option is prefixed with __DEVEL__ and generates a warning message when used. Eventually, once we get to the point where all controller's behaviors are consistent enough to implement unified hierarchy, the __DEVEL__ prefix will be dropped, and more importantly, unified-hierarchy will enforce sane_behavior by default. Maybe we'll able to completely drop the crazy stuff after a while, maybe not, but we at least have a strategy to move on to saner behaviors. This patch introduces the mount option and changes the following behaviors in cgroup core. * Mount options "noprefix" and "clone_children" are disallowed. Also, cgroupfs file cgroup.clone_children is not created. * When mounting an existing superblock, mount options should match. This is currently pretty crazy. If one mounts a cgroup, creates a subdirectory, unmounts it and then mount it again with different option, it looks like the new options are applied but they aren't. * Remount is disallowed. The behaviors changes are documented in the comment above CGRP_ROOT_SANE_BEHAVIOR enum and will be expanded as different controllers are converted and planned improvements progress. v2: Dropped unnecessary explicit file permission setting sane_behavior cftype entry as suggested by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com>
2013-04-15 07:15:26 +04:00
{
seq_puts(seq, "0\n");
return 0;
}
static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask)
{
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
struct cgroup_subsys *ss;
bool printed = false;
int ssid;
do_each_subsys_mask(ss, ssid, ss_mask) {
if (printed)
seq_putc(seq, ' ');
seq_printf(seq, "%s", ss->name);
printed = true;
} while_each_subsys_mask();
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
if (printed)
seq_putc(seq, '\n');
}
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
/* show controllers which are currently attached to the default hierarchy */
static int cgroup_root_controllers_show(struct seq_file *seq, void *v)
{
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
struct cgroup *cgrp = seq_css(seq)->cgroup;
cgroup_print_ss_mask(seq, cgrp->root->subsys_mask &
~cgrp_dfl_inhibit_ss_mask);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
return 0;
}
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
/* show controllers which are enabled from the parent */
static int cgroup_controllers_show(struct seq_file *seq, void *v)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
struct cgroup *cgrp = seq_css(seq)->cgroup;
cgroup_print_ss_mask(seq, cgroup_parent(cgrp)->subtree_control);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
return 0;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
/* show controllers which are enabled for a given cgroup's children */
static int cgroup_subtree_control_show(struct seq_file *seq, void *v)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
struct cgroup *cgrp = seq_css(seq)->cgroup;
cgroup_print_ss_mask(seq, cgrp->subtree_control);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
return 0;
}
/**
* cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy
* @cgrp: root of the subtree to update csses for
*
* @cgrp's subtree_ss_mask has changed and its subtree's (self excluded)
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
* css associations need to be updated accordingly. This function looks up
* all css_sets which are attached to the subtree, creates the matching
* updated css_sets and migrates the tasks to the new ones.
*/
static int cgroup_update_dfl_csses(struct cgroup *cgrp)
{
LIST_HEAD(preloaded_csets);
struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
struct cgroup_subsys_state *css;
struct css_set *src_cset;
int ret;
lockdep_assert_held(&cgroup_mutex);
percpu_down_write(&cgroup_threadgroup_rwsem);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
/* look up all csses currently attached to @cgrp's subtree */
spin_lock_bh(&css_set_lock);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
css_for_each_descendant_pre(css, cgroup_css(cgrp, NULL)) {
struct cgrp_cset_link *link;
/* self is not affected by subtree_ss_mask change */
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
if (css->cgroup == cgrp)
continue;
list_for_each_entry(link, &css->cgroup->cset_links, cset_link)
cgroup_migrate_add_src(link->cset, cgrp,
&preloaded_csets);
}
spin_unlock_bh(&css_set_lock);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
/* NULL dst indicates self on default hierarchy */
ret = cgroup_migrate_prepare_dst(NULL, &preloaded_csets);
if (ret)
goto out_finish;
spin_lock_bh(&css_set_lock);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) {
struct task_struct *task, *ntask;
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
/* src_csets precede dst_csets, break on the first dst_cset */
if (!src_cset->mg_src_cgrp)
break;
/* all tasks in src_csets need to be migrated */
list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list)
cgroup_taskset_add(task, &tset);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
}
spin_unlock_bh(&css_set_lock);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
ret = cgroup_taskset_migrate(&tset, cgrp);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
out_finish:
cgroup_migrate_finish(&preloaded_csets);
percpu_up_write(&cgroup_threadgroup_rwsem);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
return ret;
}
/* change the enabled child controllers for a cgroup in the default hierarchy */
static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
char *buf, size_t nbytes,
loff_t off)
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
{
u16 enable = 0, disable = 0;
u16 css_enable, css_disable, old_sc, new_sc, old_ss, new_ss;
struct cgroup *cgrp, *child;
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
struct cgroup_subsys *ss;
char *tok;
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
int ssid, ret;
/*
* Parse input - space separated list of subsystem names prefixed
* with either + or -.
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
*/
buf = strstrip(buf);
while ((tok = strsep(&buf, " "))) {
if (tok[0] == '\0')
continue;
do_each_subsys_mask(ss, ssid, ~cgrp_dfl_inhibit_ss_mask) {
if (!cgroup_ssid_enabled(ssid) ||
strcmp(tok + 1, ss->name))
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
continue;
if (*tok == '+') {
enable |= 1 << ssid;
disable &= ~(1 << ssid);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
} else if (*tok == '-') {
disable |= 1 << ssid;
enable &= ~(1 << ssid);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
} else {
return -EINVAL;
}
break;
} while_each_subsys_mask();
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
if (ssid == CGROUP_SUBSYS_COUNT)
return -EINVAL;
}
cgrp = cgroup_kn_lock_live(of->kn);
if (!cgrp)
return -ENODEV;
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
for_each_subsys(ss, ssid) {
if (enable & (1 << ssid)) {
if (cgrp->subtree_control & (1 << ssid)) {
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
enable &= ~(1 << ssid);
continue;
}
/* unavailable or not enabled on the parent? */
if (!(cgrp_dfl_root.subsys_mask & (1 << ssid)) ||
(cgroup_parent(cgrp) &&
!(cgroup_parent(cgrp)->subtree_control & (1 << ssid)))) {
ret = -ENOENT;
goto out_unlock;
}
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
} else if (disable & (1 << ssid)) {
if (!(cgrp->subtree_control & (1 << ssid))) {
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
disable &= ~(1 << ssid);
continue;
}
/* a child has it enabled? */
cgroup_for_each_live_child(child, cgrp) {
if (child->subtree_control & (1 << ssid)) {
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
ret = -EBUSY;
goto out_unlock;
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
}
}
}
}
if (!enable && !disable) {
ret = 0;
goto out_unlock;
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
}
/*
* Except for the root, subtree_control must be zero for a cgroup
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
* with tasks so that child cgroups don't compete against tasks.
*/
if (enable && cgroup_parent(cgrp) && !list_empty(&cgrp->cset_links)) {
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
ret = -EBUSY;
goto out_unlock;
}
/*
* Update subsys masks and calculate what needs to be done. More
* subsystems than specified may need to be enabled or disabled
* depending on subsystem dependencies.
*/
old_sc = cgrp->subtree_control;
old_ss = cgrp->subtree_ss_mask;
new_sc = (old_sc | enable) & ~disable;
new_ss = cgroup_calc_subtree_ss_mask(cgrp, new_sc);
css_enable = ~old_ss & new_ss;
css_disable = old_ss & ~new_ss;
enable |= css_enable;
disable |= css_disable;
cgroup: fix the async css offline wait logic in cgroup_subtree_control_write() When a subsystem is offlined, its entry on @cgrp->subsys[] is cleared asynchronously. If cgroup_subtree_control_write() is requested to enable the subsystem again before the entry is cleared, it has to wait for the previous offlining to finish and clear the @cgrp->subsys[] entry before trying to enable the subsystem again. This is currently done while verifying the input enable / disable parameters. This used to be correct but f63070d350e3 ("cgroup: make interface files visible iff enabled on cgroup->subtree_control") breaks it. The commit is one of the commits implementing subsystem dependency. Through subsystem dependency, some subsystems may be enabled and disabled implicitly in addition to the explicitly requested ones. The actual subsystems to be enabled and disabled are determined during @css_enable/disable calculation. The current offline wait logic skips the ones which are already implicitly enabled and then waits for subsystems in @enable; however, this misses the subsystems which may be implicitly enabled through dependency from @enable. If such implicitly subsystem hasn't yet finished offlining yet, the function ends up trying to create a css when its @cgrp->subsys[] slot is already occupied triggering BUG_ON() in init_and_link_css(). Fix it by moving the wait logic after @css_enable is calculated and waiting for all the subsystems in @css_enable. This fixes the above bug as the mask contains all subsystems which are to be enabled including the ones enabled through dependencies. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: f63070d350e3 ("cgroup: make interface files visible iff enabled on cgroup->subtree_control") Acked-by: Zefan Li <lizefan@huawei.com>
2014-11-18 10:49:51 +03:00
/*
* Because css offlining is asynchronous, userland might try to
* re-enable the same controller while the previous instance is
* still around. In such cases, wait till it's gone using
* offline_waitq.
*/
do_each_subsys_mask(ss, ssid, css_enable) {
cgroup: fix the async css offline wait logic in cgroup_subtree_control_write() When a subsystem is offlined, its entry on @cgrp->subsys[] is cleared asynchronously. If cgroup_subtree_control_write() is requested to enable the subsystem again before the entry is cleared, it has to wait for the previous offlining to finish and clear the @cgrp->subsys[] entry before trying to enable the subsystem again. This is currently done while verifying the input enable / disable parameters. This used to be correct but f63070d350e3 ("cgroup: make interface files visible iff enabled on cgroup->subtree_control") breaks it. The commit is one of the commits implementing subsystem dependency. Through subsystem dependency, some subsystems may be enabled and disabled implicitly in addition to the explicitly requested ones. The actual subsystems to be enabled and disabled are determined during @css_enable/disable calculation. The current offline wait logic skips the ones which are already implicitly enabled and then waits for subsystems in @enable; however, this misses the subsystems which may be implicitly enabled through dependency from @enable. If such implicitly subsystem hasn't yet finished offlining yet, the function ends up trying to create a css when its @cgrp->subsys[] slot is already occupied triggering BUG_ON() in init_and_link_css(). Fix it by moving the wait logic after @css_enable is calculated and waiting for all the subsystems in @css_enable. This fixes the above bug as the mask contains all subsystems which are to be enabled including the ones enabled through dependencies. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: f63070d350e3 ("cgroup: make interface files visible iff enabled on cgroup->subtree_control") Acked-by: Zefan Li <lizefan@huawei.com>
2014-11-18 10:49:51 +03:00
cgroup_for_each_live_child(child, cgrp) {
DEFINE_WAIT(wait);
if (!cgroup_css(child, ss))
continue;
cgroup_get(child);
prepare_to_wait(&child->offline_waitq, &wait,
TASK_UNINTERRUPTIBLE);
cgroup_kn_unlock(of->kn);
schedule();
finish_wait(&child->offline_waitq, &wait);
cgroup_put(child);
return restart_syscall();
}
} while_each_subsys_mask();
cgroup: fix the async css offline wait logic in cgroup_subtree_control_write() When a subsystem is offlined, its entry on @cgrp->subsys[] is cleared asynchronously. If cgroup_subtree_control_write() is requested to enable the subsystem again before the entry is cleared, it has to wait for the previous offlining to finish and clear the @cgrp->subsys[] entry before trying to enable the subsystem again. This is currently done while verifying the input enable / disable parameters. This used to be correct but f63070d350e3 ("cgroup: make interface files visible iff enabled on cgroup->subtree_control") breaks it. The commit is one of the commits implementing subsystem dependency. Through subsystem dependency, some subsystems may be enabled and disabled implicitly in addition to the explicitly requested ones. The actual subsystems to be enabled and disabled are determined during @css_enable/disable calculation. The current offline wait logic skips the ones which are already implicitly enabled and then waits for subsystems in @enable; however, this misses the subsystems which may be implicitly enabled through dependency from @enable. If such implicitly subsystem hasn't yet finished offlining yet, the function ends up trying to create a css when its @cgrp->subsys[] slot is already occupied triggering BUG_ON() in init_and_link_css(). Fix it by moving the wait logic after @css_enable is calculated and waiting for all the subsystems in @css_enable. This fixes the above bug as the mask contains all subsystems which are to be enabled including the ones enabled through dependencies. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: f63070d350e3 ("cgroup: make interface files visible iff enabled on cgroup->subtree_control") Acked-by: Zefan Li <lizefan@huawei.com>
2014-11-18 10:49:51 +03:00
cgrp->subtree_control = new_sc;
cgrp->subtree_ss_mask = new_ss;
/*
* Create new csses or make the existing ones visible. A css is
* created invisible if it's being implicitly enabled through
* dependency. An invisible css is made visible when the userland
* explicitly enables it.
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
*/
do_each_subsys_mask(ss, ssid, enable) {
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
cgroup_for_each_live_child(child, cgrp) {
if (css_enable & (1 << ssid)) {
struct cgroup_subsys_state *css;
css = css_create(child, ss);
if (IS_ERR(css)) {
ret = PTR_ERR(css);
goto err_undo_css;
}
if (cgrp->subtree_control & (1 << ssid)) {
ret = css_populate_dir(css, NULL);
if (ret)
goto err_undo_css;
}
} else {
ret = css_populate_dir(cgroup_css(child, ss),
NULL);
if (ret)
goto err_undo_css;
}
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
}
} while_each_subsys_mask();
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
/*
* At this point, cgroup_e_css() results reflect the new csses
* making the following cgroup_update_dfl_csses() properly update
* css associations of all tasks in the subtree.
*/
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
ret = cgroup_update_dfl_csses(cgrp);
if (ret)
goto err_undo_css;
/*
* All tasks are migrated out of disabled csses. Kill or hide
* them. A css is hidden when the userland requests it to be
* disabled while other subsystems are still depending on it. The
* css must not actively control resources and be in the vanilla
* state if it's made visible again later. Controllers which may
* be depended upon should provide ->css_reset() for this purpose.
*/
do_each_subsys_mask(ss, ssid, disable) {
cgroup_for_each_live_child(child, cgrp) {
struct cgroup_subsys_state *css = cgroup_css(child, ss);
if (css_disable & (1 << ssid)) {
kill_css(css);
} else {
css_clear_dir(css, NULL);
if (ss->css_reset)
ss->css_reset(css);
}
}
} while_each_subsys_mask();
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
kernfs_activate(cgrp->kn);
ret = 0;
out_unlock:
cgroup_kn_unlock(of->kn);
return ret ?: nbytes;
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
err_undo_css:
cgrp->subtree_control = old_sc;
cgrp->subtree_ss_mask = old_ss;
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
do_each_subsys_mask(ss, ssid, enable) {
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
cgroup_for_each_live_child(child, cgrp) {
struct cgroup_subsys_state *css = cgroup_css(child, ss);
if (!css)
continue;
if (css_enable & (1 << ssid))
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
kill_css(css);
else
css_clear_dir(css, NULL);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
}
} while_each_subsys_mask();
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
goto out_unlock;
}
static int cgroup_events_show(struct seq_file *seq, void *v)
cgroup: implement cgroup.populated for the default hierarchy cgroup users often need a way to determine when a cgroup's subhierarchy becomes empty so that it can be cleaned up. cgroup currently provides release_agent for it; unfortunately, this mechanism is riddled with issues. * It delivers events by forking and execing a userland binary specified as the release_agent. This is a long deprecated method of notification delivery. It's extremely heavy, slow and cumbersome to integrate with larger infrastructure. * There is single monitoring point at the root. There's no way to delegate management of a subtree. * The event isn't recursive. It triggers when a cgroup doesn't have any tasks or child cgroups. Events for internal nodes trigger only after all children are removed. This again makes it impossible to delegate management of a subtree. * Events are filtered from the kernel side. "notify_on_release" file is used to subscribe to or suppress release event. This is unnecessarily complicated and probably done this way because event delivery itself was expensive. This patch implements interface file "cgroup.populated" which can be used to monitor whether the cgroup's subhierarchy has tasks in it or not. Its value is 0 if there is no task in the cgroup and its descendants; otherwise, 1, and kernfs_notify() notificaiton is triggers when the value changes, which can be monitored through poll and [di]notify. This is a lot ligther and simpler and trivially allows delegating management of subhierarchy - subhierarchy monitoring can block further propgation simply by putting itself or another process in the root of the subhierarchy and monitor events that it's interested in from there without interfering with monitoring higher in the tree. v2: Patch description updated as per Serge. v3: "cgroup.subtree_populated" renamed to "cgroup.populated". The subtree_ prefix was a bit confusing because "cgroup.subtree_control" uses it to denote the tree rooted at the cgroup sans the cgroup itself while the populated state includes the cgroup itself. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Lennart Poettering <lennart@poettering.net>
2014-04-26 02:28:02 +04:00
{
seq_printf(seq, "populated %d\n",
cgroup_is_populated(seq_css(seq)->cgroup));
cgroup: implement cgroup.populated for the default hierarchy cgroup users often need a way to determine when a cgroup's subhierarchy becomes empty so that it can be cleaned up. cgroup currently provides release_agent for it; unfortunately, this mechanism is riddled with issues. * It delivers events by forking and execing a userland binary specified as the release_agent. This is a long deprecated method of notification delivery. It's extremely heavy, slow and cumbersome to integrate with larger infrastructure. * There is single monitoring point at the root. There's no way to delegate management of a subtree. * The event isn't recursive. It triggers when a cgroup doesn't have any tasks or child cgroups. Events for internal nodes trigger only after all children are removed. This again makes it impossible to delegate management of a subtree. * Events are filtered from the kernel side. "notify_on_release" file is used to subscribe to or suppress release event. This is unnecessarily complicated and probably done this way because event delivery itself was expensive. This patch implements interface file "cgroup.populated" which can be used to monitor whether the cgroup's subhierarchy has tasks in it or not. Its value is 0 if there is no task in the cgroup and its descendants; otherwise, 1, and kernfs_notify() notificaiton is triggers when the value changes, which can be monitored through poll and [di]notify. This is a lot ligther and simpler and trivially allows delegating management of subhierarchy - subhierarchy monitoring can block further propgation simply by putting itself or another process in the root of the subhierarchy and monitor events that it's interested in from there without interfering with monitoring higher in the tree. v2: Patch description updated as per Serge. v3: "cgroup.subtree_populated" renamed to "cgroup.populated". The subtree_ prefix was a bit confusing because "cgroup.subtree_control" uses it to denote the tree rooted at the cgroup sans the cgroup itself while the populated state includes the cgroup itself. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Lennart Poettering <lennart@poettering.net>
2014-04-26 02:28:02 +04:00
return 0;
}
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf,
size_t nbytes, loff_t off)
{
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct cgroup *cgrp = of->kn->parent->priv;
struct cftype *cft = of->kn->priv;
struct cgroup_subsys_state *css;
int ret;
if (cft->write)
return cft->write(of, buf, nbytes, off);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
/*
* kernfs guarantees that a file isn't deleted with operations in
* flight, which means that the matching css is and stays alive and
* doesn't need to be pinned. The RCU locking is not necessary
* either. It's just for the convenience of using cgroup_css().
*/
rcu_read_lock();
css = cgroup_css(cgrp, cft->ss);
rcu_read_unlock();
if (cft->write_u64) {
unsigned long long v;
ret = kstrtoull(buf, 0, &v);
if (!ret)
ret = cft->write_u64(css, cft, v);
} else if (cft->write_s64) {
long long v;
ret = kstrtoll(buf, 0, &v);
if (!ret)
ret = cft->write_s64(css, cft, v);
} else {
ret = -EINVAL;
}
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
return ret ?: nbytes;
}
static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos)
{
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
return seq_cft(seq)->seq_start(seq, ppos);
}
static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
return seq_cft(seq)->seq_next(seq, v, ppos);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
static void cgroup_seqfile_stop(struct seq_file *seq, void *v)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
seq_cft(seq)->seq_stop(seq, v);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
static int cgroup_seqfile_show(struct seq_file *m, void *arg)
{
struct cftype *cft = seq_cft(m);
struct cgroup_subsys_state *css = seq_css(m);
if (cft->seq_show)
return cft->seq_show(m, arg);
if (cft->read_u64)
seq_printf(m, "%llu\n", cft->read_u64(css, cft));
else if (cft->read_s64)
seq_printf(m, "%lld\n", cft->read_s64(css, cft));
else
return -EINVAL;
return 0;
}
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
static struct kernfs_ops cgroup_kf_single_ops = {
.atomic_write_len = PAGE_SIZE,
.write = cgroup_file_write,
.seq_show = cgroup_seqfile_show,
};
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
static struct kernfs_ops cgroup_kf_ops = {
.atomic_write_len = PAGE_SIZE,
.write = cgroup_file_write,
.seq_start = cgroup_seqfile_start,
.seq_next = cgroup_seqfile_next,
.seq_stop = cgroup_seqfile_stop,
.seq_show = cgroup_seqfile_show,
};
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/*
* cgroup_rename - Only allow simple rename of directories in place.
*/
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
const char *new_name_str)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct cgroup *cgrp = kn->priv;
int ret;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
if (kernfs_type(kn) != KERNFS_DIR)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
return -ENOTDIR;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
if (kn->parent != new_parent)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
return -EIO;
/*
* This isn't a proper migration and its usefulness is very
* limited. Disallow on the default hierarchy.
*/
if (cgroup_on_dfl(cgrp))
return -EPERM;
/*
* We're gonna grab cgroup_mutex which nests outside kernfs
* active_ref. kernfs_rename() doesn't require active_ref
* protection. Break them before grabbing cgroup_mutex.
*/
kernfs_break_active_protection(new_parent);
kernfs_break_active_protection(kn);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
mutex_lock(&cgroup_mutex);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
ret = kernfs_rename(kn, new_parent, new_name_str);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
mutex_unlock(&cgroup_mutex);
kernfs_unbreak_active_protection(kn);
kernfs_unbreak_active_protection(new_parent);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
return ret;
}
/* set uid and gid of cgroup dirs and files to that of the creator */
static int cgroup_kn_set_ugid(struct kernfs_node *kn)
{
struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
.ia_uid = current_fsuid(),
.ia_gid = current_fsgid(), };
if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
return 0;
return kernfs_setattr(kn, &iattr);
}
static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
struct cftype *cft)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
char name[CGROUP_FILE_NAME_MAX];
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct kernfs_node *kn;
struct lock_class_key *key = NULL;
int ret;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
#ifdef CONFIG_DEBUG_LOCK_ALLOC
key = &cft->lockdep_key;
#endif
kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
cgroup_file_mode(cft), 0, cft->kf_ops, cft,
NULL, key);
if (IS_ERR(kn))
return PTR_ERR(kn);
ret = cgroup_kn_set_ugid(kn);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
if (ret) {
kernfs_remove(kn);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
return ret;
}
if (cft->file_offset) {
struct cgroup_file *cfile = (void *)css + cft->file_offset;
spin_lock_irq(&cgroup_file_kn_lock);
cfile->kn = kn;
spin_unlock_irq(&cgroup_file_kn_lock);
}
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
return 0;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
/**
* cgroup_addrm_files - add or remove files to a cgroup directory
* @css: the target css
* @cgrp: the target cgroup (usually css->cgroup)
* @cfts: array of cftypes to be added
* @is_add: whether to add or remove
*
* Depending on @is_add, add or remove files defined by @cfts on @cgrp.
* For removals, this function never fails.
*/
static int cgroup_addrm_files(struct cgroup_subsys_state *css,
struct cgroup *cgrp, struct cftype cfts[],
bool is_add)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
struct cftype *cft, *cft_end = NULL;
int ret = 0;
lockdep_assert_held(&cgroup_mutex);
restart:
for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) {
/* does cft->flags tell us to skip this file on @cgrp? */
if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
continue;
if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp))
cgroup: introduce sane_behavior mount option It's a sad fact that at this point various cgroup controllers are carrying so many idiosyncrasies and pure insanities that it simply isn't possible to reach any sort of sane consistent behavior while maintaining staying fully compatible with what already has been exposed to userland. As we can't break exposed userland interface, transitioning to sane behaviors can only be done in steps while maintaining backwards compatibility. This patch introduces a new mount option - __DEVEL__sane_behavior - which disables crazy features and enforces consistent behaviors in cgroup core proper and various controllers. As exactly which behaviors it changes are still being determined, the mount option, at this point, is useful only for development of the new behaviors. As such, the mount option is prefixed with __DEVEL__ and generates a warning message when used. Eventually, once we get to the point where all controller's behaviors are consistent enough to implement unified hierarchy, the __DEVEL__ prefix will be dropped, and more importantly, unified-hierarchy will enforce sane_behavior by default. Maybe we'll able to completely drop the crazy stuff after a while, maybe not, but we at least have a strategy to move on to saner behaviors. This patch introduces the mount option and changes the following behaviors in cgroup core. * Mount options "noprefix" and "clone_children" are disallowed. Also, cgroupfs file cgroup.clone_children is not created. * When mounting an existing superblock, mount options should match. This is currently pretty crazy. If one mounts a cgroup, creates a subdirectory, unmounts it and then mount it again with different option, it looks like the new options are applied but they aren't. * Remount is disallowed. The behaviors changes are documented in the comment above CGRP_ROOT_SANE_BEHAVIOR enum and will be expanded as different controllers are converted and planned improvements progress. v2: Dropped unnecessary explicit file permission setting sane_behavior cftype entry as suggested by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com>
2013-04-15 07:15:26 +04:00
continue;
if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp))
continue;
if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp))
continue;
if (is_add) {
ret = cgroup_add_file(css, cgrp, cft);
if (ret) {
pr_warn("%s: failed to add %s, err=%d\n",
__func__, cft->name, ret);
cft_end = cft;
is_add = false;
goto restart;
}
} else {
cgroup_rm_file(cgrp, cft);
}
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
return ret;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add)
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
{
LIST_HEAD(pending);
struct cgroup_subsys *ss = cfts[0].ss;
struct cgroup *root = &ss->root->cgrp;
2013-08-09 04:11:25 +04:00
struct cgroup_subsys_state *css;
int ret = 0;
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
lockdep_assert_held(&cgroup_mutex);
/* add/rm files for all cgroups created before */
css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
2013-08-09 04:11:25 +04:00
struct cgroup *cgrp = css->cgroup;
if (!(css->flags & CSS_VISIBLE))
continue;
ret = cgroup_addrm_files(css, cgrp, cfts, is_add);
if (ret)
break;
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
}
if (is_add && !ret)
kernfs_activate(root->kn);
return ret;
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
}
static void cgroup_exit_cftypes(struct cftype *cfts)
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
{
struct cftype *cft;
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
for (cft = cfts; cft->name[0] != '\0'; cft++) {
/* free copy for custom atomic_write_len, see init_cftypes() */
if (cft->max_write_len && cft->max_write_len != PAGE_SIZE)
kfree(cft->kf_ops);
cft->kf_ops = NULL;
cft->ss = NULL;
cgroup: distinguish the default and legacy hierarchies when handling cftypes Until now, cftype arrays carried files for both the default and legacy hierarchies and the files which needed to be used on only one of them were flagged with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE. This gets confusing very quickly and we may end up exposing interface files to the default hierarchy without thinking it through. This patch makes cgroup core provide separate sets of interfaces for cftype handling so that the cftypes for the default and legacy hierarchies are clearly distinguished. The previous two patches renamed the existing ones so that they clearly indicate that they're for the legacy hierarchies. This patch adds the interface for the default hierarchy and apply them selectively depending on the hierarchy type. * cftypes added through cgroup_subsys->dfl_cftypes and cgroup_add_dfl_cftypes() only show up on the default hierarchy. * cftypes added through cgroup_subsys->legacy_cftypes and cgroup_add_legacy_cftypes() only show up on the legacy hierarchies. * cgroup_subsys->dfl_cftypes and ->legacy_cftypes can point to the same array for the cases where the interface files are identical on both types of hierarchies. * This makes all the existing subsystem interface files legacy-only by default and all subsystems will have no interface file created when enabled on the default hierarchy. Each subsystem should explicitly review and compose the interface for the default hierarchy. * A boot param "cgroup__DEVEL__legacy_files_on_dfl" is added which makes subsystems which haven't decided the interface files for the default hierarchy to present the legacy files on the default hierarchy so that its behavior on the default hierarchy can be tested. As the awkward name suggests, this is for development only. * memcg's CFTYPE_INSANE on "use_hierarchy" is noop now as the whole array isn't used on the default hierarchy. The flag is removed. v2: Updated documentation for cgroup__DEVEL__legacy_files_on_dfl. v3: Clear CFTYPE_ONLY_ON_DFL and CFTYPE_INSANE when cfts are removed as suggested by Li. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Aristeu Rozanski <aris@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2014-07-15 19:05:10 +04:00
/* revert flags set by cgroup core while adding @cfts */
cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
}
}
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
{
struct cftype *cft;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
for (cft = cfts; cft->name[0] != '\0'; cft++) {
struct kernfs_ops *kf_ops;
WARN_ON(cft->ss || cft->kf_ops);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
if (cft->seq_start)
kf_ops = &cgroup_kf_ops;
else
kf_ops = &cgroup_kf_single_ops;
/*
* Ugh... if @cft wants a custom max_write_len, we need to
* make a copy of kf_ops to set its atomic_write_len.
*/
if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) {
kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL);
if (!kf_ops) {
cgroup_exit_cftypes(cfts);
return -ENOMEM;
}
kf_ops->atomic_write_len = cft->max_write_len;
}
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
cft->kf_ops = kf_ops;
cft->ss = ss;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
}
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
return 0;
}
static int cgroup_rm_cftypes_locked(struct cftype *cfts)
{
lockdep_assert_held(&cgroup_mutex);
if (!cfts || !cfts[0].ss)
return -ENOENT;
list_del(&cfts->node);
cgroup_apply_cftypes(cfts, false);
cgroup_exit_cftypes(cfts);
return 0;
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
}
/**
* cgroup_rm_cftypes - remove an array of cftypes from a subsystem
* @cfts: zero-length name terminated array of cftypes
*
* Unregister @cfts. Files described by @cfts are removed from all
* existing cgroups and all future cgroups won't have them either. This
* function can be called anytime whether @cfts' subsys is attached or not.
*
* Returns 0 on successful unregistration, -ENOENT if @cfts is not
* registered.
*/
int cgroup_rm_cftypes(struct cftype *cfts)
{
int ret;
mutex_lock(&cgroup_mutex);
ret = cgroup_rm_cftypes_locked(cfts);
mutex_unlock(&cgroup_mutex);
return ret;
}
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
/**
* cgroup_add_cftypes - add an array of cftypes to a subsystem
* @ss: target cgroup subsystem
* @cfts: zero-length name terminated array of cftypes
*
* Register @cfts to @ss. Files described by @cfts are created for all
* existing cgroups to which @ss is attached and all future cgroups will
* have them too. This function can be called anytime whether @ss is
* attached or not.
*
* Returns 0 on successful registration, -errno on failure. Note that this
* function currently returns 0 as long as @cfts registration is successful
* even if some file creation attempts on existing cgroups fail.
*/
static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
{
int ret;
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
if (!cgroup_ssid_enabled(ss->id))
return 0;
if (!cfts || cfts[0].name[0] == '\0')
return 0;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
ret = cgroup_init_cftypes(ss, cfts);
if (ret)
return ret;
mutex_lock(&cgroup_mutex);
list_add_tail(&cfts->node, &ss->cfts);
ret = cgroup_apply_cftypes(cfts, true);
if (ret)
cgroup_rm_cftypes_locked(cfts);
mutex_unlock(&cgroup_mutex);
return ret;
}
cgroup: distinguish the default and legacy hierarchies when handling cftypes Until now, cftype arrays carried files for both the default and legacy hierarchies and the files which needed to be used on only one of them were flagged with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE. This gets confusing very quickly and we may end up exposing interface files to the default hierarchy without thinking it through. This patch makes cgroup core provide separate sets of interfaces for cftype handling so that the cftypes for the default and legacy hierarchies are clearly distinguished. The previous two patches renamed the existing ones so that they clearly indicate that they're for the legacy hierarchies. This patch adds the interface for the default hierarchy and apply them selectively depending on the hierarchy type. * cftypes added through cgroup_subsys->dfl_cftypes and cgroup_add_dfl_cftypes() only show up on the default hierarchy. * cftypes added through cgroup_subsys->legacy_cftypes and cgroup_add_legacy_cftypes() only show up on the legacy hierarchies. * cgroup_subsys->dfl_cftypes and ->legacy_cftypes can point to the same array for the cases where the interface files are identical on both types of hierarchies. * This makes all the existing subsystem interface files legacy-only by default and all subsystems will have no interface file created when enabled on the default hierarchy. Each subsystem should explicitly review and compose the interface for the default hierarchy. * A boot param "cgroup__DEVEL__legacy_files_on_dfl" is added which makes subsystems which haven't decided the interface files for the default hierarchy to present the legacy files on the default hierarchy so that its behavior on the default hierarchy can be tested. As the awkward name suggests, this is for development only. * memcg's CFTYPE_INSANE on "use_hierarchy" is noop now as the whole array isn't used on the default hierarchy. The flag is removed. v2: Updated documentation for cgroup__DEVEL__legacy_files_on_dfl. v3: Clear CFTYPE_ONLY_ON_DFL and CFTYPE_INSANE when cfts are removed as suggested by Li. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Aristeu Rozanski <aris@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2014-07-15 19:05:10 +04:00
/**
* cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
* @ss: target cgroup subsystem
* @cfts: zero-length name terminated array of cftypes
*
* Similar to cgroup_add_cftypes() but the added files are only used for
* the default hierarchy.
*/
int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
{
struct cftype *cft;
for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
cft->flags |= __CFTYPE_ONLY_ON_DFL;
cgroup: distinguish the default and legacy hierarchies when handling cftypes Until now, cftype arrays carried files for both the default and legacy hierarchies and the files which needed to be used on only one of them were flagged with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE. This gets confusing very quickly and we may end up exposing interface files to the default hierarchy without thinking it through. This patch makes cgroup core provide separate sets of interfaces for cftype handling so that the cftypes for the default and legacy hierarchies are clearly distinguished. The previous two patches renamed the existing ones so that they clearly indicate that they're for the legacy hierarchies. This patch adds the interface for the default hierarchy and apply them selectively depending on the hierarchy type. * cftypes added through cgroup_subsys->dfl_cftypes and cgroup_add_dfl_cftypes() only show up on the default hierarchy. * cftypes added through cgroup_subsys->legacy_cftypes and cgroup_add_legacy_cftypes() only show up on the legacy hierarchies. * cgroup_subsys->dfl_cftypes and ->legacy_cftypes can point to the same array for the cases where the interface files are identical on both types of hierarchies. * This makes all the existing subsystem interface files legacy-only by default and all subsystems will have no interface file created when enabled on the default hierarchy. Each subsystem should explicitly review and compose the interface for the default hierarchy. * A boot param "cgroup__DEVEL__legacy_files_on_dfl" is added which makes subsystems which haven't decided the interface files for the default hierarchy to present the legacy files on the default hierarchy so that its behavior on the default hierarchy can be tested. As the awkward name suggests, this is for development only. * memcg's CFTYPE_INSANE on "use_hierarchy" is noop now as the whole array isn't used on the default hierarchy. The flag is removed. v2: Updated documentation for cgroup__DEVEL__legacy_files_on_dfl. v3: Clear CFTYPE_ONLY_ON_DFL and CFTYPE_INSANE when cfts are removed as suggested by Li. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Aristeu Rozanski <aris@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2014-07-15 19:05:10 +04:00
return cgroup_add_cftypes(ss, cfts);
}
/**
* cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
* @ss: target cgroup subsystem
* @cfts: zero-length name terminated array of cftypes
*
* Similar to cgroup_add_cftypes() but the added files are only used for
* the legacy hierarchies.
*/
int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
{
cgroup: distinguish the default and legacy hierarchies when handling cftypes Until now, cftype arrays carried files for both the default and legacy hierarchies and the files which needed to be used on only one of them were flagged with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE. This gets confusing very quickly and we may end up exposing interface files to the default hierarchy without thinking it through. This patch makes cgroup core provide separate sets of interfaces for cftype handling so that the cftypes for the default and legacy hierarchies are clearly distinguished. The previous two patches renamed the existing ones so that they clearly indicate that they're for the legacy hierarchies. This patch adds the interface for the default hierarchy and apply them selectively depending on the hierarchy type. * cftypes added through cgroup_subsys->dfl_cftypes and cgroup_add_dfl_cftypes() only show up on the default hierarchy. * cftypes added through cgroup_subsys->legacy_cftypes and cgroup_add_legacy_cftypes() only show up on the legacy hierarchies. * cgroup_subsys->dfl_cftypes and ->legacy_cftypes can point to the same array for the cases where the interface files are identical on both types of hierarchies. * This makes all the existing subsystem interface files legacy-only by default and all subsystems will have no interface file created when enabled on the default hierarchy. Each subsystem should explicitly review and compose the interface for the default hierarchy. * A boot param "cgroup__DEVEL__legacy_files_on_dfl" is added which makes subsystems which haven't decided the interface files for the default hierarchy to present the legacy files on the default hierarchy so that its behavior on the default hierarchy can be tested. As the awkward name suggests, this is for development only. * memcg's CFTYPE_INSANE on "use_hierarchy" is noop now as the whole array isn't used on the default hierarchy. The flag is removed. v2: Updated documentation for cgroup__DEVEL__legacy_files_on_dfl. v3: Clear CFTYPE_ONLY_ON_DFL and CFTYPE_INSANE when cfts are removed as suggested by Li. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Aristeu Rozanski <aris@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2014-07-15 19:05:10 +04:00
struct cftype *cft;
for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
cft->flags |= __CFTYPE_NOT_ON_DFL;
return cgroup_add_cftypes(ss, cfts);
}
/**
* cgroup_file_notify - generate a file modified event for a cgroup_file
* @cfile: target cgroup_file
*
* @cfile must have been obtained by setting cftype->file_offset.
*/
void cgroup_file_notify(struct cgroup_file *cfile)
{
unsigned long flags;
spin_lock_irqsave(&cgroup_file_kn_lock, flags);
if (cfile->kn)
kernfs_notify(cfile->kn);
spin_unlock_irqrestore(&cgroup_file_kn_lock, flags);
}
/**
* cgroup_task_count - count the number of tasks in a cgroup.
* @cgrp: the cgroup in question
*
* Return the number of tasks in the cgroup.
*/
static int cgroup_task_count(const struct cgroup *cgrp)
{
int count = 0;
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
struct cgrp_cset_link *link;
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
spin_lock_bh(&css_set_lock);
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
list_for_each_entry(link, &cgrp->cset_links, cset_link)
count += atomic_read(&link->cset->refcount);
spin_unlock_bh(&css_set_lock);
return count;
}
cgroup: add cgroup->serial_nr and implement cgroup_next_sibling() Currently, there's no easy way to find out the next sibling cgroup unless it's known that the current cgroup is accessed from the parent's children list in a single RCU critical section. This in turn forces all iterators to require whole iteration to be enclosed in a single RCU critical section, which sometimes is too restrictive. This patch implements cgroup_next_sibling() which can reliably determine the next sibling regardless of the state of the current cgroup as long as it's accessible. It currently is impossible to determine the next sibling after dropping RCU read lock because the cgroup being iterated could be removed anytime and if RCU read lock is dropped, nothing guarantess its ->sibling.next pointer is accessible. A removed cgroup would continue to point to its next sibling for RCU accesses but stop receiving updates from the sibling. IOW, the next sibling could be removed and then complete its grace period while RCU read lock is dropped, making it unsafe to dereference ->sibling.next after dropping and re-acquiring RCU read lock. This can be solved by adding a way to traverse to the next sibling without dereferencing ->sibling.next. This patch adds a monotonically increasing cgroup serial number, cgroup->serial_nr, which guarantees that all cgroup->children lists are kept in increasing serial_nr order. A new function, cgroup_next_sibling(), is implemented, which, if CGRP_REMOVED is not set on the current cgroup, follows ->sibling.next; otherwise, traverses the parent's ->children list until it sees a sibling with higher ->serial_nr. This allows the function to always return the next sibling regardless of the state of the current cgroup without adding overhead in the fast path. Further patches will update the iterators to use cgroup_next_sibling() so that they allow dropping RCU read lock and blocking while iteration is in progress which in turn will be used to simplify controllers. v2: Typo fix as per Serge. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
2013-05-24 05:55:38 +04:00
/**
2013-08-09 04:11:25 +04:00
* css_next_child - find the next child of a given css
cgroup: iterate cgroup_subsys_states directly Currently, css_next_child() is implemented as finding the next child cgroup which has the css enabled, which used to be the only way to do it as only cgroups participated in sibling lists and thus could be iteratd. This works as long as what's required during iteration is not missing online csses; however, it turns out that there are use cases where offlined but not yet released csses need to be iterated. This is difficult to implement through cgroup iteration the unified hierarchy as there may be multiple dying csses for the same subsystem associated with single cgroup. After the recent changes, the cgroup self and regular csses behave identically in how they're linked and unlinked from the sibling lists including assertion of CSS_RELEASED and css_next_child() can simply switch to iterating csses directly. This both simplifies the logic and ensures that all visible non-released csses are included in the iteration whether there are multiple dying csses for a subsystem or not. As all other iterators depend on css_next_child() for sibling iteration, this changes behaviors of all css iterators. Add and update explanations on the css states which are included in traversal to all iterators. As css iteration could always contain offlined csses, this shouldn't break any of the current users and new usages which need iteration of all on and offline csses can make use of the new semantics. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16 21:22:51 +04:00
* @pos: the current position (%NULL to initiate traversal)
* @parent: css whose children to walk
cgroup: add cgroup->serial_nr and implement cgroup_next_sibling() Currently, there's no easy way to find out the next sibling cgroup unless it's known that the current cgroup is accessed from the parent's children list in a single RCU critical section. This in turn forces all iterators to require whole iteration to be enclosed in a single RCU critical section, which sometimes is too restrictive. This patch implements cgroup_next_sibling() which can reliably determine the next sibling regardless of the state of the current cgroup as long as it's accessible. It currently is impossible to determine the next sibling after dropping RCU read lock because the cgroup being iterated could be removed anytime and if RCU read lock is dropped, nothing guarantess its ->sibling.next pointer is accessible. A removed cgroup would continue to point to its next sibling for RCU accesses but stop receiving updates from the sibling. IOW, the next sibling could be removed and then complete its grace period while RCU read lock is dropped, making it unsafe to dereference ->sibling.next after dropping and re-acquiring RCU read lock. This can be solved by adding a way to traverse to the next sibling without dereferencing ->sibling.next. This patch adds a monotonically increasing cgroup serial number, cgroup->serial_nr, which guarantees that all cgroup->children lists are kept in increasing serial_nr order. A new function, cgroup_next_sibling(), is implemented, which, if CGRP_REMOVED is not set on the current cgroup, follows ->sibling.next; otherwise, traverses the parent's ->children list until it sees a sibling with higher ->serial_nr. This allows the function to always return the next sibling regardless of the state of the current cgroup without adding overhead in the fast path. Further patches will update the iterators to use cgroup_next_sibling() so that they allow dropping RCU read lock and blocking while iteration is in progress which in turn will be used to simplify controllers. v2: Typo fix as per Serge. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
2013-05-24 05:55:38 +04:00
*
cgroup: iterate cgroup_subsys_states directly Currently, css_next_child() is implemented as finding the next child cgroup which has the css enabled, which used to be the only way to do it as only cgroups participated in sibling lists and thus could be iteratd. This works as long as what's required during iteration is not missing online csses; however, it turns out that there are use cases where offlined but not yet released csses need to be iterated. This is difficult to implement through cgroup iteration the unified hierarchy as there may be multiple dying csses for the same subsystem associated with single cgroup. After the recent changes, the cgroup self and regular csses behave identically in how they're linked and unlinked from the sibling lists including assertion of CSS_RELEASED and css_next_child() can simply switch to iterating csses directly. This both simplifies the logic and ensures that all visible non-released csses are included in the iteration whether there are multiple dying csses for a subsystem or not. As all other iterators depend on css_next_child() for sibling iteration, this changes behaviors of all css iterators. Add and update explanations on the css states which are included in traversal to all iterators. As css iteration could always contain offlined csses, this shouldn't break any of the current users and new usages which need iteration of all on and offline csses can make use of the new semantics. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16 21:22:51 +04:00
* This function returns the next child of @parent and should be called
* under either cgroup_mutex or RCU read lock. The only requirement is
cgroup: iterate cgroup_subsys_states directly Currently, css_next_child() is implemented as finding the next child cgroup which has the css enabled, which used to be the only way to do it as only cgroups participated in sibling lists and thus could be iteratd. This works as long as what's required during iteration is not missing online csses; however, it turns out that there are use cases where offlined but not yet released csses need to be iterated. This is difficult to implement through cgroup iteration the unified hierarchy as there may be multiple dying csses for the same subsystem associated with single cgroup. After the recent changes, the cgroup self and regular csses behave identically in how they're linked and unlinked from the sibling lists including assertion of CSS_RELEASED and css_next_child() can simply switch to iterating csses directly. This both simplifies the logic and ensures that all visible non-released csses are included in the iteration whether there are multiple dying csses for a subsystem or not. As all other iterators depend on css_next_child() for sibling iteration, this changes behaviors of all css iterators. Add and update explanations on the css states which are included in traversal to all iterators. As css iteration could always contain offlined csses, this shouldn't break any of the current users and new usages which need iteration of all on and offline csses can make use of the new semantics. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16 21:22:51 +04:00
* that @parent and @pos are accessible. The next sibling is guaranteed to
* be returned regardless of their states.
*
* If a subsystem synchronizes ->css_online() and the start of iteration, a
* css which finished ->css_online() is guaranteed to be visible in the
* future iterations and will stay visible until the last reference is put.
* A css which hasn't finished ->css_online() or already finished
* ->css_offline() may show up during traversal. It's each subsystem's
* responsibility to synchronize against on/offlining.
cgroup: add cgroup->serial_nr and implement cgroup_next_sibling() Currently, there's no easy way to find out the next sibling cgroup unless it's known that the current cgroup is accessed from the parent's children list in a single RCU critical section. This in turn forces all iterators to require whole iteration to be enclosed in a single RCU critical section, which sometimes is too restrictive. This patch implements cgroup_next_sibling() which can reliably determine the next sibling regardless of the state of the current cgroup as long as it's accessible. It currently is impossible to determine the next sibling after dropping RCU read lock because the cgroup being iterated could be removed anytime and if RCU read lock is dropped, nothing guarantess its ->sibling.next pointer is accessible. A removed cgroup would continue to point to its next sibling for RCU accesses but stop receiving updates from the sibling. IOW, the next sibling could be removed and then complete its grace period while RCU read lock is dropped, making it unsafe to dereference ->sibling.next after dropping and re-acquiring RCU read lock. This can be solved by adding a way to traverse to the next sibling without dereferencing ->sibling.next. This patch adds a monotonically increasing cgroup serial number, cgroup->serial_nr, which guarantees that all cgroup->children lists are kept in increasing serial_nr order. A new function, cgroup_next_sibling(), is implemented, which, if CGRP_REMOVED is not set on the current cgroup, follows ->sibling.next; otherwise, traverses the parent's ->children list until it sees a sibling with higher ->serial_nr. This allows the function to always return the next sibling regardless of the state of the current cgroup without adding overhead in the fast path. Further patches will update the iterators to use cgroup_next_sibling() so that they allow dropping RCU read lock and blocking while iteration is in progress which in turn will be used to simplify controllers. v2: Typo fix as per Serge. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
2013-05-24 05:55:38 +04:00
*/
cgroup: iterate cgroup_subsys_states directly Currently, css_next_child() is implemented as finding the next child cgroup which has the css enabled, which used to be the only way to do it as only cgroups participated in sibling lists and thus could be iteratd. This works as long as what's required during iteration is not missing online csses; however, it turns out that there are use cases where offlined but not yet released csses need to be iterated. This is difficult to implement through cgroup iteration the unified hierarchy as there may be multiple dying csses for the same subsystem associated with single cgroup. After the recent changes, the cgroup self and regular csses behave identically in how they're linked and unlinked from the sibling lists including assertion of CSS_RELEASED and css_next_child() can simply switch to iterating csses directly. This both simplifies the logic and ensures that all visible non-released csses are included in the iteration whether there are multiple dying csses for a subsystem or not. As all other iterators depend on css_next_child() for sibling iteration, this changes behaviors of all css iterators. Add and update explanations on the css states which are included in traversal to all iterators. As css iteration could always contain offlined csses, this shouldn't break any of the current users and new usages which need iteration of all on and offline csses can make use of the new semantics. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16 21:22:51 +04:00
struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
struct cgroup_subsys_state *parent)
cgroup: add cgroup->serial_nr and implement cgroup_next_sibling() Currently, there's no easy way to find out the next sibling cgroup unless it's known that the current cgroup is accessed from the parent's children list in a single RCU critical section. This in turn forces all iterators to require whole iteration to be enclosed in a single RCU critical section, which sometimes is too restrictive. This patch implements cgroup_next_sibling() which can reliably determine the next sibling regardless of the state of the current cgroup as long as it's accessible. It currently is impossible to determine the next sibling after dropping RCU read lock because the cgroup being iterated could be removed anytime and if RCU read lock is dropped, nothing guarantess its ->sibling.next pointer is accessible. A removed cgroup would continue to point to its next sibling for RCU accesses but stop receiving updates from the sibling. IOW, the next sibling could be removed and then complete its grace period while RCU read lock is dropped, making it unsafe to dereference ->sibling.next after dropping and re-acquiring RCU read lock. This can be solved by adding a way to traverse to the next sibling without dereferencing ->sibling.next. This patch adds a monotonically increasing cgroup serial number, cgroup->serial_nr, which guarantees that all cgroup->children lists are kept in increasing serial_nr order. A new function, cgroup_next_sibling(), is implemented, which, if CGRP_REMOVED is not set on the current cgroup, follows ->sibling.next; otherwise, traverses the parent's ->children list until it sees a sibling with higher ->serial_nr. This allows the function to always return the next sibling regardless of the state of the current cgroup without adding overhead in the fast path. Further patches will update the iterators to use cgroup_next_sibling() so that they allow dropping RCU read lock and blocking while iteration is in progress which in turn will be used to simplify controllers. v2: Typo fix as per Serge. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
2013-05-24 05:55:38 +04:00
{
cgroup: iterate cgroup_subsys_states directly Currently, css_next_child() is implemented as finding the next child cgroup which has the css enabled, which used to be the only way to do it as only cgroups participated in sibling lists and thus could be iteratd. This works as long as what's required during iteration is not missing online csses; however, it turns out that there are use cases where offlined but not yet released csses need to be iterated. This is difficult to implement through cgroup iteration the unified hierarchy as there may be multiple dying csses for the same subsystem associated with single cgroup. After the recent changes, the cgroup self and regular csses behave identically in how they're linked and unlinked from the sibling lists including assertion of CSS_RELEASED and css_next_child() can simply switch to iterating csses directly. This both simplifies the logic and ensures that all visible non-released csses are included in the iteration whether there are multiple dying csses for a subsystem or not. As all other iterators depend on css_next_child() for sibling iteration, this changes behaviors of all css iterators. Add and update explanations on the css states which are included in traversal to all iterators. As css iteration could always contain offlined csses, this shouldn't break any of the current users and new usages which need iteration of all on and offline csses can make use of the new semantics. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16 21:22:51 +04:00
struct cgroup_subsys_state *next;
cgroup: add cgroup->serial_nr and implement cgroup_next_sibling() Currently, there's no easy way to find out the next sibling cgroup unless it's known that the current cgroup is accessed from the parent's children list in a single RCU critical section. This in turn forces all iterators to require whole iteration to be enclosed in a single RCU critical section, which sometimes is too restrictive. This patch implements cgroup_next_sibling() which can reliably determine the next sibling regardless of the state of the current cgroup as long as it's accessible. It currently is impossible to determine the next sibling after dropping RCU read lock because the cgroup being iterated could be removed anytime and if RCU read lock is dropped, nothing guarantess its ->sibling.next pointer is accessible. A removed cgroup would continue to point to its next sibling for RCU accesses but stop receiving updates from the sibling. IOW, the next sibling could be removed and then complete its grace period while RCU read lock is dropped, making it unsafe to dereference ->sibling.next after dropping and re-acquiring RCU read lock. This can be solved by adding a way to traverse to the next sibling without dereferencing ->sibling.next. This patch adds a monotonically increasing cgroup serial number, cgroup->serial_nr, which guarantees that all cgroup->children lists are kept in increasing serial_nr order. A new function, cgroup_next_sibling(), is implemented, which, if CGRP_REMOVED is not set on the current cgroup, follows ->sibling.next; otherwise, traverses the parent's ->children list until it sees a sibling with higher ->serial_nr. This allows the function to always return the next sibling regardless of the state of the current cgroup without adding overhead in the fast path. Further patches will update the iterators to use cgroup_next_sibling() so that they allow dropping RCU read lock and blocking while iteration is in progress which in turn will be used to simplify controllers. v2: Typo fix as per Serge. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
2013-05-24 05:55:38 +04:00
cgroup_assert_mutex_or_rcu_locked();
cgroup: add cgroup->serial_nr and implement cgroup_next_sibling() Currently, there's no easy way to find out the next sibling cgroup unless it's known that the current cgroup is accessed from the parent's children list in a single RCU critical section. This in turn forces all iterators to require whole iteration to be enclosed in a single RCU critical section, which sometimes is too restrictive. This patch implements cgroup_next_sibling() which can reliably determine the next sibling regardless of the state of the current cgroup as long as it's accessible. It currently is impossible to determine the next sibling after dropping RCU read lock because the cgroup being iterated could be removed anytime and if RCU read lock is dropped, nothing guarantess its ->sibling.next pointer is accessible. A removed cgroup would continue to point to its next sibling for RCU accesses but stop receiving updates from the sibling. IOW, the next sibling could be removed and then complete its grace period while RCU read lock is dropped, making it unsafe to dereference ->sibling.next after dropping and re-acquiring RCU read lock. This can be solved by adding a way to traverse to the next sibling without dereferencing ->sibling.next. This patch adds a monotonically increasing cgroup serial number, cgroup->serial_nr, which guarantees that all cgroup->children lists are kept in increasing serial_nr order. A new function, cgroup_next_sibling(), is implemented, which, if CGRP_REMOVED is not set on the current cgroup, follows ->sibling.next; otherwise, traverses the parent's ->children list until it sees a sibling with higher ->serial_nr. This allows the function to always return the next sibling regardless of the state of the current cgroup without adding overhead in the fast path. Further patches will update the iterators to use cgroup_next_sibling() so that they allow dropping RCU read lock and blocking while iteration is in progress which in turn will be used to simplify controllers. v2: Typo fix as per Serge. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
2013-05-24 05:55:38 +04:00
/*
* @pos could already have been unlinked from the sibling list.
* Once a cgroup is removed, its ->sibling.next is no longer
* updated when its next sibling changes. CSS_RELEASED is set when
* @pos is taken off list, at which time its next pointer is valid,
* and, as releases are serialized, the one pointed to by the next
* pointer is guaranteed to not have started release yet. This
* implies that if we observe !CSS_RELEASED on @pos in this RCU
* critical section, the one pointed to by its next pointer is
* guaranteed to not have finished its RCU grace period even if we
* have dropped rcu_read_lock() inbetween iterations.
*
* If @pos has CSS_RELEASED set, its next pointer can't be
* dereferenced; however, as each css is given a monotonically
* increasing unique serial number and always appended to the
* sibling list, the next one can be found by walking the parent's
* children until the first css with higher serial number than
* @pos's. While this path can be slower, it happens iff iteration
* races against release and the race window is very small.
cgroup: add cgroup->serial_nr and implement cgroup_next_sibling() Currently, there's no easy way to find out the next sibling cgroup unless it's known that the current cgroup is accessed from the parent's children list in a single RCU critical section. This in turn forces all iterators to require whole iteration to be enclosed in a single RCU critical section, which sometimes is too restrictive. This patch implements cgroup_next_sibling() which can reliably determine the next sibling regardless of the state of the current cgroup as long as it's accessible. It currently is impossible to determine the next sibling after dropping RCU read lock because the cgroup being iterated could be removed anytime and if RCU read lock is dropped, nothing guarantess its ->sibling.next pointer is accessible. A removed cgroup would continue to point to its next sibling for RCU accesses but stop receiving updates from the sibling. IOW, the next sibling could be removed and then complete its grace period while RCU read lock is dropped, making it unsafe to dereference ->sibling.next after dropping and re-acquiring RCU read lock. This can be solved by adding a way to traverse to the next sibling without dereferencing ->sibling.next. This patch adds a monotonically increasing cgroup serial number, cgroup->serial_nr, which guarantees that all cgroup->children lists are kept in increasing serial_nr order. A new function, cgroup_next_sibling(), is implemented, which, if CGRP_REMOVED is not set on the current cgroup, follows ->sibling.next; otherwise, traverses the parent's ->children list until it sees a sibling with higher ->serial_nr. This allows the function to always return the next sibling regardless of the state of the current cgroup without adding overhead in the fast path. Further patches will update the iterators to use cgroup_next_sibling() so that they allow dropping RCU read lock and blocking while iteration is in progress which in turn will be used to simplify controllers. v2: Typo fix as per Serge. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
2013-05-24 05:55:38 +04:00
*/
if (!pos) {
cgroup: iterate cgroup_subsys_states directly Currently, css_next_child() is implemented as finding the next child cgroup which has the css enabled, which used to be the only way to do it as only cgroups participated in sibling lists and thus could be iteratd. This works as long as what's required during iteration is not missing online csses; however, it turns out that there are use cases where offlined but not yet released csses need to be iterated. This is difficult to implement through cgroup iteration the unified hierarchy as there may be multiple dying csses for the same subsystem associated with single cgroup. After the recent changes, the cgroup self and regular csses behave identically in how they're linked and unlinked from the sibling lists including assertion of CSS_RELEASED and css_next_child() can simply switch to iterating csses directly. This both simplifies the logic and ensures that all visible non-released csses are included in the iteration whether there are multiple dying csses for a subsystem or not. As all other iterators depend on css_next_child() for sibling iteration, this changes behaviors of all css iterators. Add and update explanations on the css states which are included in traversal to all iterators. As css iteration could always contain offlined csses, this shouldn't break any of the current users and new usages which need iteration of all on and offline csses can make use of the new semantics. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16 21:22:51 +04:00
next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling);
} else if (likely(!(pos->flags & CSS_RELEASED))) {
next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling);
} else {
cgroup: iterate cgroup_subsys_states directly Currently, css_next_child() is implemented as finding the next child cgroup which has the css enabled, which used to be the only way to do it as only cgroups participated in sibling lists and thus could be iteratd. This works as long as what's required during iteration is not missing online csses; however, it turns out that there are use cases where offlined but not yet released csses need to be iterated. This is difficult to implement through cgroup iteration the unified hierarchy as there may be multiple dying csses for the same subsystem associated with single cgroup. After the recent changes, the cgroup self and regular csses behave identically in how they're linked and unlinked from the sibling lists including assertion of CSS_RELEASED and css_next_child() can simply switch to iterating csses directly. This both simplifies the logic and ensures that all visible non-released csses are included in the iteration whether there are multiple dying csses for a subsystem or not. As all other iterators depend on css_next_child() for sibling iteration, this changes behaviors of all css iterators. Add and update explanations on the css states which are included in traversal to all iterators. As css iteration could always contain offlined csses, this shouldn't break any of the current users and new usages which need iteration of all on and offline csses can make use of the new semantics. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16 21:22:51 +04:00
list_for_each_entry_rcu(next, &parent->children, sibling)
if (next->serial_nr > pos->serial_nr)
break;
cgroup: add cgroup->serial_nr and implement cgroup_next_sibling() Currently, there's no easy way to find out the next sibling cgroup unless it's known that the current cgroup is accessed from the parent's children list in a single RCU critical section. This in turn forces all iterators to require whole iteration to be enclosed in a single RCU critical section, which sometimes is too restrictive. This patch implements cgroup_next_sibling() which can reliably determine the next sibling regardless of the state of the current cgroup as long as it's accessible. It currently is impossible to determine the next sibling after dropping RCU read lock because the cgroup being iterated could be removed anytime and if RCU read lock is dropped, nothing guarantess its ->sibling.next pointer is accessible. A removed cgroup would continue to point to its next sibling for RCU accesses but stop receiving updates from the sibling. IOW, the next sibling could be removed and then complete its grace period while RCU read lock is dropped, making it unsafe to dereference ->sibling.next after dropping and re-acquiring RCU read lock. This can be solved by adding a way to traverse to the next sibling without dereferencing ->sibling.next. This patch adds a monotonically increasing cgroup serial number, cgroup->serial_nr, which guarantees that all cgroup->children lists are kept in increasing serial_nr order. A new function, cgroup_next_sibling(), is implemented, which, if CGRP_REMOVED is not set on the current cgroup, follows ->sibling.next; otherwise, traverses the parent's ->children list until it sees a sibling with higher ->serial_nr. This allows the function to always return the next sibling regardless of the state of the current cgroup without adding overhead in the fast path. Further patches will update the iterators to use cgroup_next_sibling() so that they allow dropping RCU read lock and blocking while iteration is in progress which in turn will be used to simplify controllers. v2: Typo fix as per Serge. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
2013-05-24 05:55:38 +04:00
}
/*
* @next, if not pointing to the head, can be dereferenced and is
cgroup: iterate cgroup_subsys_states directly Currently, css_next_child() is implemented as finding the next child cgroup which has the css enabled, which used to be the only way to do it as only cgroups participated in sibling lists and thus could be iteratd. This works as long as what's required during iteration is not missing online csses; however, it turns out that there are use cases where offlined but not yet released csses need to be iterated. This is difficult to implement through cgroup iteration the unified hierarchy as there may be multiple dying csses for the same subsystem associated with single cgroup. After the recent changes, the cgroup self and regular csses behave identically in how they're linked and unlinked from the sibling lists including assertion of CSS_RELEASED and css_next_child() can simply switch to iterating csses directly. This both simplifies the logic and ensures that all visible non-released csses are included in the iteration whether there are multiple dying csses for a subsystem or not. As all other iterators depend on css_next_child() for sibling iteration, this changes behaviors of all css iterators. Add and update explanations on the css states which are included in traversal to all iterators. As css iteration could always contain offlined csses, this shouldn't break any of the current users and new usages which need iteration of all on and offline csses can make use of the new semantics. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16 21:22:51 +04:00
* the next sibling.
*/
cgroup: iterate cgroup_subsys_states directly Currently, css_next_child() is implemented as finding the next child cgroup which has the css enabled, which used to be the only way to do it as only cgroups participated in sibling lists and thus could be iteratd. This works as long as what's required during iteration is not missing online csses; however, it turns out that there are use cases where offlined but not yet released csses need to be iterated. This is difficult to implement through cgroup iteration the unified hierarchy as there may be multiple dying csses for the same subsystem associated with single cgroup. After the recent changes, the cgroup self and regular csses behave identically in how they're linked and unlinked from the sibling lists including assertion of CSS_RELEASED and css_next_child() can simply switch to iterating csses directly. This both simplifies the logic and ensures that all visible non-released csses are included in the iteration whether there are multiple dying csses for a subsystem or not. As all other iterators depend on css_next_child() for sibling iteration, this changes behaviors of all css iterators. Add and update explanations on the css states which are included in traversal to all iterators. As css iteration could always contain offlined csses, this shouldn't break any of the current users and new usages which need iteration of all on and offline csses can make use of the new semantics. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16 21:22:51 +04:00
if (&next->sibling != &parent->children)
return next;
return NULL;
cgroup: add cgroup->serial_nr and implement cgroup_next_sibling() Currently, there's no easy way to find out the next sibling cgroup unless it's known that the current cgroup is accessed from the parent's children list in a single RCU critical section. This in turn forces all iterators to require whole iteration to be enclosed in a single RCU critical section, which sometimes is too restrictive. This patch implements cgroup_next_sibling() which can reliably determine the next sibling regardless of the state of the current cgroup as long as it's accessible. It currently is impossible to determine the next sibling after dropping RCU read lock because the cgroup being iterated could be removed anytime and if RCU read lock is dropped, nothing guarantess its ->sibling.next pointer is accessible. A removed cgroup would continue to point to its next sibling for RCU accesses but stop receiving updates from the sibling. IOW, the next sibling could be removed and then complete its grace period while RCU read lock is dropped, making it unsafe to dereference ->sibling.next after dropping and re-acquiring RCU read lock. This can be solved by adding a way to traverse to the next sibling without dereferencing ->sibling.next. This patch adds a monotonically increasing cgroup serial number, cgroup->serial_nr, which guarantees that all cgroup->children lists are kept in increasing serial_nr order. A new function, cgroup_next_sibling(), is implemented, which, if CGRP_REMOVED is not set on the current cgroup, follows ->sibling.next; otherwise, traverses the parent's ->children list until it sees a sibling with higher ->serial_nr. This allows the function to always return the next sibling regardless of the state of the current cgroup without adding overhead in the fast path. Further patches will update the iterators to use cgroup_next_sibling() so that they allow dropping RCU read lock and blocking while iteration is in progress which in turn will be used to simplify controllers. v2: Typo fix as per Serge. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
2013-05-24 05:55:38 +04:00
}
/**
2013-08-09 04:11:25 +04:00
* css_next_descendant_pre - find the next descendant for pre-order walk
* @pos: the current position (%NULL to initiate traversal)
2013-08-09 04:11:25 +04:00
* @root: css whose descendants to walk
*
2013-08-09 04:11:25 +04:00
* To be used by css_for_each_descendant_pre(). Find the next descendant
cgroup: make css_for_each_descendant() and friends include the origin css in the iteration Previously, all css descendant iterators didn't include the origin (root of subtree) css in the iteration. The reasons were maintaining consistency with css_for_each_child() and that at the time of introduction more use cases needed skipping the origin anyway; however, given that css_is_descendant() considers self to be a descendant, omitting the origin css has become more confusing and looking at the accumulated use cases rather clearly indicates that including origin would result in simpler code overall. While this is a change which can easily lead to subtle bugs, cgroup API including the iterators has recently gone through major restructuring and no out-of-tree changes will be applicable without adjustments making this a relatively acceptable opportunity for this type of change. The conversions are mostly straight-forward. If the iteration block had explicit origin handling before or after, it's moved inside the iteration. If not, if (pos == origin) continue; is added. Some conversions add extra reference get/put around origin handling by consolidating origin handling and the rest. While the extra ref operations aren't strictly necessary, this shouldn't cause any noticeable difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Jens Axboe <axboe@kernel.dk> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com>
2013-08-09 04:11:27 +04:00
* to visit for pre-order traversal of @root's descendants. @root is
* included in the iteration and the first node to be visited.
*
* While this function requires cgroup_mutex or RCU read locking, it
* doesn't require the whole traversal to be contained in a single critical
* section. This function will return the correct next descendant as long
* as both @pos and @root are accessible and @pos is a descendant of @root.
cgroup: iterate cgroup_subsys_states directly Currently, css_next_child() is implemented as finding the next child cgroup which has the css enabled, which used to be the only way to do it as only cgroups participated in sibling lists and thus could be iteratd. This works as long as what's required during iteration is not missing online csses; however, it turns out that there are use cases where offlined but not yet released csses need to be iterated. This is difficult to implement through cgroup iteration the unified hierarchy as there may be multiple dying csses for the same subsystem associated with single cgroup. After the recent changes, the cgroup self and regular csses behave identically in how they're linked and unlinked from the sibling lists including assertion of CSS_RELEASED and css_next_child() can simply switch to iterating csses directly. This both simplifies the logic and ensures that all visible non-released csses are included in the iteration whether there are multiple dying csses for a subsystem or not. As all other iterators depend on css_next_child() for sibling iteration, this changes behaviors of all css iterators. Add and update explanations on the css states which are included in traversal to all iterators. As css iteration could always contain offlined csses, this shouldn't break any of the current users and new usages which need iteration of all on and offline csses can make use of the new semantics. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16 21:22:51 +04:00
*
* If a subsystem synchronizes ->css_online() and the start of iteration, a
* css which finished ->css_online() is guaranteed to be visible in the
* future iterations and will stay visible until the last reference is put.
* A css which hasn't finished ->css_online() or already finished
* ->css_offline() may show up during traversal. It's each subsystem's
* responsibility to synchronize against on/offlining.
*/
2013-08-09 04:11:25 +04:00
struct cgroup_subsys_state *
css_next_descendant_pre(struct cgroup_subsys_state *pos,
struct cgroup_subsys_state *root)
{
2013-08-09 04:11:25 +04:00
struct cgroup_subsys_state *next;
cgroup_assert_mutex_or_rcu_locked();
cgroup: make css_for_each_descendant() and friends include the origin css in the iteration Previously, all css descendant iterators didn't include the origin (root of subtree) css in the iteration. The reasons were maintaining consistency with css_for_each_child() and that at the time of introduction more use cases needed skipping the origin anyway; however, given that css_is_descendant() considers self to be a descendant, omitting the origin css has become more confusing and looking at the accumulated use cases rather clearly indicates that including origin would result in simpler code overall. While this is a change which can easily lead to subtle bugs, cgroup API including the iterators has recently gone through major restructuring and no out-of-tree changes will be applicable without adjustments making this a relatively acceptable opportunity for this type of change. The conversions are mostly straight-forward. If the iteration block had explicit origin handling before or after, it's moved inside the iteration. If not, if (pos == origin) continue; is added. Some conversions add extra reference get/put around origin handling by consolidating origin handling and the rest. While the extra ref operations aren't strictly necessary, this shouldn't cause any noticeable difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Jens Axboe <axboe@kernel.dk> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com>
2013-08-09 04:11:27 +04:00
/* if first iteration, visit @root */
if (!pos)
cgroup: make css_for_each_descendant() and friends include the origin css in the iteration Previously, all css descendant iterators didn't include the origin (root of subtree) css in the iteration. The reasons were maintaining consistency with css_for_each_child() and that at the time of introduction more use cases needed skipping the origin anyway; however, given that css_is_descendant() considers self to be a descendant, omitting the origin css has become more confusing and looking at the accumulated use cases rather clearly indicates that including origin would result in simpler code overall. While this is a change which can easily lead to subtle bugs, cgroup API including the iterators has recently gone through major restructuring and no out-of-tree changes will be applicable without adjustments making this a relatively acceptable opportunity for this type of change. The conversions are mostly straight-forward. If the iteration block had explicit origin handling before or after, it's moved inside the iteration. If not, if (pos == origin) continue; is added. Some conversions add extra reference get/put around origin handling by consolidating origin handling and the rest. While the extra ref operations aren't strictly necessary, this shouldn't cause any noticeable difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Jens Axboe <axboe@kernel.dk> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com>
2013-08-09 04:11:27 +04:00
return root;
/* visit the first child if exists */
2013-08-09 04:11:25 +04:00
next = css_next_child(NULL, pos);
if (next)
return next;
/* no child, visit my or the closest ancestor's next sibling */
2013-08-09 04:11:25 +04:00
while (pos != root) {
next = css_next_child(pos, pos->parent);
if (next)
return next;
pos = pos->parent;
}
return NULL;
}
/**
2013-08-09 04:11:25 +04:00
* css_rightmost_descendant - return the rightmost descendant of a css
* @pos: css of interest
*
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* Return the rightmost descendant of @pos. If there's no descendant, @pos
* is returned. This can be used during pre-order traversal to skip
* subtree of @pos.
*
* While this function requires cgroup_mutex or RCU read locking, it
* doesn't require the whole traversal to be contained in a single critical
* section. This function will return the correct rightmost descendant as
* long as @pos is accessible.
*/
2013-08-09 04:11:25 +04:00
struct cgroup_subsys_state *
css_rightmost_descendant(struct cgroup_subsys_state *pos)
{
2013-08-09 04:11:25 +04:00
struct cgroup_subsys_state *last, *tmp;
cgroup_assert_mutex_or_rcu_locked();
do {
last = pos;
/* ->prev isn't RCU safe, walk ->next till the end */
pos = NULL;
2013-08-09 04:11:25 +04:00
css_for_each_child(tmp, last)
pos = tmp;
} while (pos);
return last;
}
2013-08-09 04:11:25 +04:00
static struct cgroup_subsys_state *
css_leftmost_descendant(struct cgroup_subsys_state *pos)
{
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struct cgroup_subsys_state *last;
do {
last = pos;
2013-08-09 04:11:25 +04:00
pos = css_next_child(NULL, pos);
} while (pos);
return last;
}
/**
2013-08-09 04:11:25 +04:00
* css_next_descendant_post - find the next descendant for post-order walk
* @pos: the current position (%NULL to initiate traversal)
2013-08-09 04:11:25 +04:00
* @root: css whose descendants to walk
*
2013-08-09 04:11:25 +04:00
* To be used by css_for_each_descendant_post(). Find the next descendant
cgroup: make css_for_each_descendant() and friends include the origin css in the iteration Previously, all css descendant iterators didn't include the origin (root of subtree) css in the iteration. The reasons were maintaining consistency with css_for_each_child() and that at the time of introduction more use cases needed skipping the origin anyway; however, given that css_is_descendant() considers self to be a descendant, omitting the origin css has become more confusing and looking at the accumulated use cases rather clearly indicates that including origin would result in simpler code overall. While this is a change which can easily lead to subtle bugs, cgroup API including the iterators has recently gone through major restructuring and no out-of-tree changes will be applicable without adjustments making this a relatively acceptable opportunity for this type of change. The conversions are mostly straight-forward. If the iteration block had explicit origin handling before or after, it's moved inside the iteration. If not, if (pos == origin) continue; is added. Some conversions add extra reference get/put around origin handling by consolidating origin handling and the rest. While the extra ref operations aren't strictly necessary, this shouldn't cause any noticeable difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Jens Axboe <axboe@kernel.dk> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com>
2013-08-09 04:11:27 +04:00
* to visit for post-order traversal of @root's descendants. @root is
* included in the iteration and the last node to be visited.
*
* While this function requires cgroup_mutex or RCU read locking, it
* doesn't require the whole traversal to be contained in a single critical
* section. This function will return the correct next descendant as long
* as both @pos and @cgroup are accessible and @pos is a descendant of
* @cgroup.
cgroup: iterate cgroup_subsys_states directly Currently, css_next_child() is implemented as finding the next child cgroup which has the css enabled, which used to be the only way to do it as only cgroups participated in sibling lists and thus could be iteratd. This works as long as what's required during iteration is not missing online csses; however, it turns out that there are use cases where offlined but not yet released csses need to be iterated. This is difficult to implement through cgroup iteration the unified hierarchy as there may be multiple dying csses for the same subsystem associated with single cgroup. After the recent changes, the cgroup self and regular csses behave identically in how they're linked and unlinked from the sibling lists including assertion of CSS_RELEASED and css_next_child() can simply switch to iterating csses directly. This both simplifies the logic and ensures that all visible non-released csses are included in the iteration whether there are multiple dying csses for a subsystem or not. As all other iterators depend on css_next_child() for sibling iteration, this changes behaviors of all css iterators. Add and update explanations on the css states which are included in traversal to all iterators. As css iteration could always contain offlined csses, this shouldn't break any of the current users and new usages which need iteration of all on and offline csses can make use of the new semantics. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org>
2014-05-16 21:22:51 +04:00
*
* If a subsystem synchronizes ->css_online() and the start of iteration, a
* css which finished ->css_online() is guaranteed to be visible in the
* future iterations and will stay visible until the last reference is put.
* A css which hasn't finished ->css_online() or already finished
* ->css_offline() may show up during traversal. It's each subsystem's
* responsibility to synchronize against on/offlining.
*/
2013-08-09 04:11:25 +04:00
struct cgroup_subsys_state *
css_next_descendant_post(struct cgroup_subsys_state *pos,
struct cgroup_subsys_state *root)
{
2013-08-09 04:11:25 +04:00
struct cgroup_subsys_state *next;
cgroup_assert_mutex_or_rcu_locked();
/* if first iteration, visit leftmost descendant which may be @root */
if (!pos)
return css_leftmost_descendant(root);
cgroup: make css_for_each_descendant() and friends include the origin css in the iteration Previously, all css descendant iterators didn't include the origin (root of subtree) css in the iteration. The reasons were maintaining consistency with css_for_each_child() and that at the time of introduction more use cases needed skipping the origin anyway; however, given that css_is_descendant() considers self to be a descendant, omitting the origin css has become more confusing and looking at the accumulated use cases rather clearly indicates that including origin would result in simpler code overall. While this is a change which can easily lead to subtle bugs, cgroup API including the iterators has recently gone through major restructuring and no out-of-tree changes will be applicable without adjustments making this a relatively acceptable opportunity for this type of change. The conversions are mostly straight-forward. If the iteration block had explicit origin handling before or after, it's moved inside the iteration. If not, if (pos == origin) continue; is added. Some conversions add extra reference get/put around origin handling by consolidating origin handling and the rest. While the extra ref operations aren't strictly necessary, this shouldn't cause any noticeable difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Jens Axboe <axboe@kernel.dk> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com>
2013-08-09 04:11:27 +04:00
/* if we visited @root, we're done */
if (pos == root)
return NULL;
/* if there's an unvisited sibling, visit its leftmost descendant */
next = css_next_child(pos, pos->parent);
if (next)
2013-08-09 04:11:25 +04:00
return css_leftmost_descendant(next);
/* no sibling left, visit parent */
return pos->parent;
}
/**
* css_has_online_children - does a css have online children
* @css: the target css
*
* Returns %true if @css has any online children; otherwise, %false. This
* function can be called from any context but the caller is responsible
* for synchronizing against on/offlining as necessary.
*/
bool css_has_online_children(struct cgroup_subsys_state *css)
{
struct cgroup_subsys_state *child;
bool ret = false;
rcu_read_lock();
css_for_each_child(child, css) {
if (child->flags & CSS_ONLINE) {
ret = true;
break;
}
}
rcu_read_unlock();
return ret;
}
/**
* css_task_iter_advance_css_set - advance a task itererator to the next css_set
* @it: the iterator to advance
*
* Advance @it to the next css_set to walk.
*/
static void css_task_iter_advance_css_set(struct css_task_iter *it)
{
struct list_head *l = it->cset_pos;
struct cgrp_cset_link *link;
struct css_set *cset;
lockdep_assert_held(&css_set_lock);
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
/* Advance to the next non-empty css_set */
do {
l = l->next;
if (l == it->cset_head) {
it->cset_pos = NULL;
it->task_pos = NULL;
return;
}
if (it->ss) {
cset = container_of(l, struct css_set,
e_cset_node[it->ss->id]);
} else {
link = list_entry(l, struct cgrp_cset_link, cset_link);
cset = link->cset;
}
} while (!css_set_populated(cset));
cgroup: add css_set->mg_tasks Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, we're going to use task->cg_list during migration too. Instead of building a separate array, target tasks will be linked into a dedicated migration list_head on the owning css_set. Tasks on the migration list are treated the same as tasks on the usual tasks list; however, being on a separate list allows cgroup migration code path to keep track of the target tasks by simply keeping the list of css_sets with tasks being migrated, making unpredictable dynamic allocation unnecessary. In prepartion of such migration path update, this patch introduces css_set->mg_tasks list and updates css_set task iterations so that they walk both css_set->tasks and ->mg_tasks. Note that ->mg_tasks isn't used yet. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
it->cset_pos = l;
cgroup: add css_set->mg_tasks Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, we're going to use task->cg_list during migration too. Instead of building a separate array, target tasks will be linked into a dedicated migration list_head on the owning css_set. Tasks on the migration list are treated the same as tasks on the usual tasks list; however, being on a separate list allows cgroup migration code path to keep track of the target tasks by simply keeping the list of css_sets with tasks being migrated, making unpredictable dynamic allocation unnecessary. In prepartion of such migration path update, this patch introduces css_set->mg_tasks list and updates css_set task iterations so that they walk both css_set->tasks and ->mg_tasks. Note that ->mg_tasks isn't used yet. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
if (!list_empty(&cset->tasks))
it->task_pos = cset->tasks.next;
cgroup: add css_set->mg_tasks Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, we're going to use task->cg_list during migration too. Instead of building a separate array, target tasks will be linked into a dedicated migration list_head on the owning css_set. Tasks on the migration list are treated the same as tasks on the usual tasks list; however, being on a separate list allows cgroup migration code path to keep track of the target tasks by simply keeping the list of css_sets with tasks being migrated, making unpredictable dynamic allocation unnecessary. In prepartion of such migration path update, this patch introduces css_set->mg_tasks list and updates css_set task iterations so that they walk both css_set->tasks and ->mg_tasks. Note that ->mg_tasks isn't used yet. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
else
it->task_pos = cset->mg_tasks.next;
it->tasks_head = &cset->tasks;
it->mg_tasks_head = &cset->mg_tasks;
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
/*
* We don't keep css_sets locked across iteration steps and thus
* need to take steps to ensure that iteration can be resumed after
* the lock is re-acquired. Iteration is performed at two levels -
* css_sets and tasks in them.
*
* Once created, a css_set never leaves its cgroup lists, so a
* pinned css_set is guaranteed to stay put and we can resume
* iteration afterwards.
*
* Tasks may leave @cset across iteration steps. This is resolved
* by registering each iterator with the css_set currently being
* walked and making css_set_move_task() advance iterators whose
* next task is leaving.
*/
if (it->cur_cset) {
list_del(&it->iters_node);
put_css_set_locked(it->cur_cset);
}
get_css_set(cset);
it->cur_cset = cset;
list_add(&it->iters_node, &cset->task_iters);
}
static void css_task_iter_advance(struct css_task_iter *it)
{
struct list_head *l = it->task_pos;
lockdep_assert_held(&css_set_lock);
WARN_ON_ONCE(!l);
/*
* Advance iterator to find next entry. cset->tasks is consumed
* first and then ->mg_tasks. After ->mg_tasks, we move onto the
* next cset.
*/
l = l->next;
if (l == it->tasks_head)
l = it->mg_tasks_head->next;
if (l == it->mg_tasks_head)
css_task_iter_advance_css_set(it);
else
it->task_pos = l;
}
/**
* css_task_iter_start - initiate task iteration
* @css: the css to walk tasks of
* @it: the task iterator to use
*
* Initiate iteration through the tasks of @css. The caller can call
* css_task_iter_next() to walk through the tasks until the function
* returns NULL. On completion of iteration, css_task_iter_end() must be
* called.
*/
void css_task_iter_start(struct cgroup_subsys_state *css,
struct css_task_iter *it)
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
{
/* no one should try to iterate before mounting cgroups */
WARN_ON_ONCE(!use_task_css_set_links);
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
memset(it, 0, sizeof(*it));
spin_lock_bh(&css_set_lock);
it->ss = css->ss;
if (it->ss)
it->cset_pos = &css->cgroup->e_csets[css->ss->id];
else
it->cset_pos = &css->cgroup->cset_links;
it->cset_head = it->cset_pos;
css_task_iter_advance_css_set(it);
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
spin_unlock_bh(&css_set_lock);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
}
/**
* css_task_iter_next - return the next task for the iterator
* @it: the task iterator being iterated
*
* The "next" function for task iteration. @it should have been
* initialized via css_task_iter_start(). Returns NULL when the iteration
* reaches the end.
*/
struct task_struct *css_task_iter_next(struct css_task_iter *it)
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
{
cgroup: fix race condition around termination check in css_task_iter_next() css_task_iter_next() checked @it->cur_task before grabbing css_set_lock and assumed that the result won't change afterwards; however, tasks could leave the cgroup being iterated terminating the iterator before css_task_lock is acquired. If this happens, css_task_iter_next() tries to calculate the current task from NULL cg_list pointer leading to the following oops. BUG: unable to handle kernel paging request at fffffffffffff7d0 IP: [<ffffffff810d5f22>] css_task_iter_next+0x42/0x80 ... CPU: 4 PID: 6391 Comm: JobQDisp2 Not tainted 4.0.9-22_fbk4_rc3_81616_ge8d9cb6 #1 Hardware name: Quanta Freedom/Winterfell, BIOS F03_3B08 03/04/2014 task: ffff880868e46400 ti: ffff88083404c000 task.ti: ffff88083404c000 RIP: 0010:[<ffffffff810d5f22>] [<ffffffff810d5f22>] css_task_iter_next+0x42/0x80 RSP: 0018:ffff88083404fd28 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff88083404fd68 RCX: ffff8804697fb8b0 RDX: fffffffffffff7c0 RSI: ffff8803b7dff800 RDI: ffffffff822c0278 RBP: ffff88083404fd38 R08: 0000000000017160 R09: ffff88046f4070c0 R10: ffffffff810d61f7 R11: 0000000000000293 R12: ffff880863bf8400 R13: ffff88046b87fd80 R14: 0000000000000000 R15: ffff88083404fe58 FS: 00007fa0567e2700(0000) GS:ffff88046f900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffffffffff7d0 CR3: 0000000469568000 CR4: 00000000001406e0 Stack: 0000000000000246 0000000000000000 ffff88083404fde8 ffffffff810d6248 ffff88083404fd68 0000000000000000 ffff8803b7dff800 000001ef000001ee 0000000000000000 0000000000000000 ffff880863bf8568 0000000000000000 Call Trace: [<ffffffff810d6248>] cgroup_pidlist_start+0x258/0x550 [<ffffffff810cf66d>] cgroup_seqfile_start+0x1d/0x20 [<ffffffff8121f8ef>] kernfs_seq_start+0x5f/0xa0 [<ffffffff811cab76>] seq_read+0x166/0x380 [<ffffffff812200fd>] kernfs_fop_read+0x11d/0x180 [<ffffffff811a7398>] __vfs_read+0x18/0x50 [<ffffffff811a745d>] vfs_read+0x8d/0x150 [<ffffffff811a756f>] SyS_read+0x4f/0xb0 [<ffffffff818d4772>] system_call_fastpath+0x12/0x17 Fix it by moving the termination condition check inside css_set_lock. @it->cur_task is now cleared after being put and @it->task_pos is tested for termination instead of @it->cset_pos as they indicate the same condition and @it->task_pos is what's being dereferenced. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Calvin Owens <calvinowens@fb.com> Fixes: ed27b9f7a17d ("cgroup: don't hold css_set_rwsem across css task iteration") Acked-by: Zefan Li <lizefan@huawei.com>
2015-10-29 05:43:05 +03:00
if (it->cur_task) {
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
put_task_struct(it->cur_task);
cgroup: fix race condition around termination check in css_task_iter_next() css_task_iter_next() checked @it->cur_task before grabbing css_set_lock and assumed that the result won't change afterwards; however, tasks could leave the cgroup being iterated terminating the iterator before css_task_lock is acquired. If this happens, css_task_iter_next() tries to calculate the current task from NULL cg_list pointer leading to the following oops. BUG: unable to handle kernel paging request at fffffffffffff7d0 IP: [<ffffffff810d5f22>] css_task_iter_next+0x42/0x80 ... CPU: 4 PID: 6391 Comm: JobQDisp2 Not tainted 4.0.9-22_fbk4_rc3_81616_ge8d9cb6 #1 Hardware name: Quanta Freedom/Winterfell, BIOS F03_3B08 03/04/2014 task: ffff880868e46400 ti: ffff88083404c000 task.ti: ffff88083404c000 RIP: 0010:[<ffffffff810d5f22>] [<ffffffff810d5f22>] css_task_iter_next+0x42/0x80 RSP: 0018:ffff88083404fd28 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff88083404fd68 RCX: ffff8804697fb8b0 RDX: fffffffffffff7c0 RSI: ffff8803b7dff800 RDI: ffffffff822c0278 RBP: ffff88083404fd38 R08: 0000000000017160 R09: ffff88046f4070c0 R10: ffffffff810d61f7 R11: 0000000000000293 R12: ffff880863bf8400 R13: ffff88046b87fd80 R14: 0000000000000000 R15: ffff88083404fe58 FS: 00007fa0567e2700(0000) GS:ffff88046f900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffffffffff7d0 CR3: 0000000469568000 CR4: 00000000001406e0 Stack: 0000000000000246 0000000000000000 ffff88083404fde8 ffffffff810d6248 ffff88083404fd68 0000000000000000 ffff8803b7dff800 000001ef000001ee 0000000000000000 0000000000000000 ffff880863bf8568 0000000000000000 Call Trace: [<ffffffff810d6248>] cgroup_pidlist_start+0x258/0x550 [<ffffffff810cf66d>] cgroup_seqfile_start+0x1d/0x20 [<ffffffff8121f8ef>] kernfs_seq_start+0x5f/0xa0 [<ffffffff811cab76>] seq_read+0x166/0x380 [<ffffffff812200fd>] kernfs_fop_read+0x11d/0x180 [<ffffffff811a7398>] __vfs_read+0x18/0x50 [<ffffffff811a745d>] vfs_read+0x8d/0x150 [<ffffffff811a756f>] SyS_read+0x4f/0xb0 [<ffffffff818d4772>] system_call_fastpath+0x12/0x17 Fix it by moving the termination condition check inside css_set_lock. @it->cur_task is now cleared after being put and @it->task_pos is tested for termination instead of @it->cset_pos as they indicate the same condition and @it->task_pos is what's being dereferenced. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Calvin Owens <calvinowens@fb.com> Fixes: ed27b9f7a17d ("cgroup: don't hold css_set_rwsem across css task iteration") Acked-by: Zefan Li <lizefan@huawei.com>
2015-10-29 05:43:05 +03:00
it->cur_task = NULL;
}
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
spin_lock_bh(&css_set_lock);
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
cgroup: fix race condition around termination check in css_task_iter_next() css_task_iter_next() checked @it->cur_task before grabbing css_set_lock and assumed that the result won't change afterwards; however, tasks could leave the cgroup being iterated terminating the iterator before css_task_lock is acquired. If this happens, css_task_iter_next() tries to calculate the current task from NULL cg_list pointer leading to the following oops. BUG: unable to handle kernel paging request at fffffffffffff7d0 IP: [<ffffffff810d5f22>] css_task_iter_next+0x42/0x80 ... CPU: 4 PID: 6391 Comm: JobQDisp2 Not tainted 4.0.9-22_fbk4_rc3_81616_ge8d9cb6 #1 Hardware name: Quanta Freedom/Winterfell, BIOS F03_3B08 03/04/2014 task: ffff880868e46400 ti: ffff88083404c000 task.ti: ffff88083404c000 RIP: 0010:[<ffffffff810d5f22>] [<ffffffff810d5f22>] css_task_iter_next+0x42/0x80 RSP: 0018:ffff88083404fd28 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff88083404fd68 RCX: ffff8804697fb8b0 RDX: fffffffffffff7c0 RSI: ffff8803b7dff800 RDI: ffffffff822c0278 RBP: ffff88083404fd38 R08: 0000000000017160 R09: ffff88046f4070c0 R10: ffffffff810d61f7 R11: 0000000000000293 R12: ffff880863bf8400 R13: ffff88046b87fd80 R14: 0000000000000000 R15: ffff88083404fe58 FS: 00007fa0567e2700(0000) GS:ffff88046f900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffffffffff7d0 CR3: 0000000469568000 CR4: 00000000001406e0 Stack: 0000000000000246 0000000000000000 ffff88083404fde8 ffffffff810d6248 ffff88083404fd68 0000000000000000 ffff8803b7dff800 000001ef000001ee 0000000000000000 0000000000000000 ffff880863bf8568 0000000000000000 Call Trace: [<ffffffff810d6248>] cgroup_pidlist_start+0x258/0x550 [<ffffffff810cf66d>] cgroup_seqfile_start+0x1d/0x20 [<ffffffff8121f8ef>] kernfs_seq_start+0x5f/0xa0 [<ffffffff811cab76>] seq_read+0x166/0x380 [<ffffffff812200fd>] kernfs_fop_read+0x11d/0x180 [<ffffffff811a7398>] __vfs_read+0x18/0x50 [<ffffffff811a745d>] vfs_read+0x8d/0x150 [<ffffffff811a756f>] SyS_read+0x4f/0xb0 [<ffffffff818d4772>] system_call_fastpath+0x12/0x17 Fix it by moving the termination condition check inside css_set_lock. @it->cur_task is now cleared after being put and @it->task_pos is tested for termination instead of @it->cset_pos as they indicate the same condition and @it->task_pos is what's being dereferenced. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Calvin Owens <calvinowens@fb.com> Fixes: ed27b9f7a17d ("cgroup: don't hold css_set_rwsem across css task iteration") Acked-by: Zefan Li <lizefan@huawei.com>
2015-10-29 05:43:05 +03:00
if (it->task_pos) {
it->cur_task = list_entry(it->task_pos, struct task_struct,
cg_list);
get_task_struct(it->cur_task);
css_task_iter_advance(it);
}
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
spin_unlock_bh(&css_set_lock);
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
return it->cur_task;
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
}
/**
* css_task_iter_end - finish task iteration
* @it: the task iterator to finish
*
* Finish task iteration started by css_task_iter_start().
*/
void css_task_iter_end(struct css_task_iter *it)
{
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
if (it->cur_cset) {
spin_lock_bh(&css_set_lock);
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
list_del(&it->iters_node);
put_css_set_locked(it->cur_cset);
spin_unlock_bh(&css_set_lock);
cgroup: don't hold css_set_rwsem across css task iteration css_sets are synchronized through css_set_rwsem but the locking scheme is kinda bizarre. The hot paths - fork and exit - have to write lock the rwsem making the rw part pointless; furthermore, many readers already hold cgroup_mutex. One of the readers is css task iteration. It read locks the rwsem over the entire duration of iteration. This leads to silly locking behavior. When cpuset tries to migrate processes of a cgroup to a different NUMA node, css_set_rwsem is held across the entire migration attempt which can take a long time locking out forking, exiting and other cgroup operations. This patch updates css task iteration so that it locks css_set_rwsem only while the iterator is being advanced. css task iteration involves two levels - css_set and task iteration. As css_sets in use are practically immutable, simply pinning the current one is enough for resuming iteration afterwards. Task iteration is tricky as tasks may leave their css_set while iteration is in progress. This is solved by keeping track of active iterators and advancing them if their next task leaves its css_set. v2: put_task_struct() in css_task_iter_next() moved outside css_set_rwsem. A later patch will add cgroup operations to task_struct free path which may grab the same lock and this avoids deadlock possibilities. css_set_move_task() updated to use list_for_each_entry_safe() when walking task_iters and advancing them. This is necessary as advancing an iter may remove it from the list. Signed-off-by: Tejun Heo <tj@kernel.org>
2015-10-15 23:41:52 +03:00
}
if (it->cur_task)
put_task_struct(it->cur_task);
}
/**
* cgroup_trasnsfer_tasks - move tasks from one cgroup to another
* @to: cgroup to which the tasks will be moved
* @from: cgroup in which the tasks currently reside
*
cgroup: update how a newly forked task gets associated with css_set When a new process is forked, cgroup_fork() associates it with the css_set of its parent but doesn't link it into it. After the new process is linked to tasklist, cgroup_post_fork() does the linking. This is problematic for cgroup_transfer_tasks() as there's no way to tell whether there are tasks which are pointing to a css_set but not linked yet. It is impossible to implement an operation which transfer all tasks of a cgroup to another and the current cgroup_transfer_tasks() can easily be tricked into leaving a newly forked process behind if it gets called between cgroup_fork() and cgroup_post_fork(). Let's make association with a css_set and linking atomic by moving it to cgroup_post_fork(). cgroup_fork() sets child->cgroups to init_css_set as a placeholder and cgroup_post_fork() is updated to perform both the association with the parent's cgroup and linking there. This means that a newly created task will point to init_css_set without holding a ref to it much like what it does on the exit path. Empty cg_list is used to indicate that the task isn't holding a ref to the associated css_set. This fixes an actual bug with cgroup_transfer_tasks(); however, I'm not marking it for -stable. The whole thing is broken in multiple other ways which require invasive updates to fix and I don't think it's worthwhile to bother with backporting this particular one. Fortunately, the only user is cpuset and these bugs don't crash the machine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
* Locking rules between cgroup_post_fork() and the migration path
* guarantee that, if a task is forking while being migrated, the new child
* is guaranteed to be either visible in the source cgroup after the
* parent's migration is complete or put into the target cgroup. No task
* can slip out of migration through forking.
*/
int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
{
LIST_HEAD(preloaded_csets);
struct cgrp_cset_link *link;
struct css_task_iter it;
struct task_struct *task;
int ret;
mutex_lock(&cgroup_mutex);
/* all tasks in @from are being moved, all csets are source */
spin_lock_bh(&css_set_lock);
list_for_each_entry(link, &from->cset_links, cset_link)
cgroup_migrate_add_src(link->cset, to, &preloaded_csets);
spin_unlock_bh(&css_set_lock);
ret = cgroup_migrate_prepare_dst(to, &preloaded_csets);
if (ret)
goto out_err;
/*
* Migrate tasks one-by-one until @from is empty. This fails iff
* ->can_attach() fails.
*/
do {
css_task_iter_start(&from->self, &it);
task = css_task_iter_next(&it);
if (task)
get_task_struct(task);
css_task_iter_end(&it);
if (task) {
ret = cgroup_migrate(task, false, to);
put_task_struct(task);
}
} while (task && !ret);
out_err:
cgroup_migrate_finish(&preloaded_csets);
mutex_unlock(&cgroup_mutex);
return ret;
}
/*
* Stuff for reading the 'tasks'/'procs' files.
*
* Reading this file can return large amounts of data if a cgroup has
* *lots* of attached tasks. So it may need several calls to read(),
* but we cannot guarantee that the information we produce is correct
* unless we produce it entirely atomically.
*
*/
/* which pidlist file are we talking about? */
enum cgroup_filetype {
CGROUP_FILE_PROCS,
CGROUP_FILE_TASKS,
};
/*
* A pidlist is a list of pids that virtually represents the contents of one
* of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
* a pair (one each for procs, tasks) for each pid namespace that's relevant
* to the cgroup.
*/
struct cgroup_pidlist {
/*
* used to find which pidlist is wanted. doesn't change as long as
* this particular list stays in the list.
*/
struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
/* array of xids */
pid_t *list;
/* how many elements the above list has */
int length;
/* each of these stored in a list by its cgroup */
struct list_head links;
/* pointer to the cgroup we belong to, for list removal purposes */
struct cgroup *owner;
2013-11-29 19:42:58 +04:00
/* for delayed destruction */
struct delayed_work destroy_dwork;
};
/*
* The following two functions "fix" the issue where there are more pids
* than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
* TODO: replace with a kernel-wide solution to this problem
*/
#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
static void *pidlist_allocate(int count)
{
if (PIDLIST_TOO_LARGE(count))
return vmalloc(count * sizeof(pid_t));
else
return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
}
2013-11-29 19:42:58 +04:00
static void pidlist_free(void *p)
{
kvfree(p);
}
2013-11-29 19:42:58 +04:00
/*
* Used to destroy all pidlists lingering waiting for destroy timer. None
* should be left afterwards.
*/
static void cgroup_pidlist_destroy_all(struct cgroup *cgrp)
{
struct cgroup_pidlist *l, *tmp_l;
mutex_lock(&cgrp->pidlist_mutex);
list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
mutex_unlock(&cgrp->pidlist_mutex);
flush_workqueue(cgroup_pidlist_destroy_wq);
BUG_ON(!list_empty(&cgrp->pidlists));
}
static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
{
struct delayed_work *dwork = to_delayed_work(work);
struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
destroy_dwork);
struct cgroup_pidlist *tofree = NULL;
mutex_lock(&l->owner->pidlist_mutex);
/*
* Destroy iff we didn't get queued again. The state won't change
* as destroy_dwork can only be queued while locked.
2013-11-29 19:42:58 +04:00
*/
if (!delayed_work_pending(dwork)) {
2013-11-29 19:42:58 +04:00
list_del(&l->links);
pidlist_free(l->list);
put_pid_ns(l->key.ns);
tofree = l;
}
mutex_unlock(&l->owner->pidlist_mutex);
kfree(tofree);
}
/*
* pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
* Returns the number of unique elements.
*/
static int pidlist_uniq(pid_t *list, int length)
{
int src, dest = 1;
/*
* we presume the 0th element is unique, so i starts at 1. trivial
* edge cases first; no work needs to be done for either
*/
if (length == 0 || length == 1)
return length;
/* src and dest walk down the list; dest counts unique elements */
for (src = 1; src < length; src++) {
/* find next unique element */
while (list[src] == list[src-1]) {
src++;
if (src == length)
goto after;
}
/* dest always points to where the next unique element goes */
list[dest] = list[src];
dest++;
}
after:
return dest;
}
/*
* The two pid files - task and cgroup.procs - guaranteed that the result
* is sorted, which forced this whole pidlist fiasco. As pid order is
* different per namespace, each namespace needs differently sorted list,
* making it impossible to use, for example, single rbtree of member tasks
* sorted by task pointer. As pidlists can be fairly large, allocating one
* per open file is dangerous, so cgroup had to implement shared pool of
* pidlists keyed by cgroup and namespace.
*
* All this extra complexity was caused by the original implementation
* committing to an entirely unnecessary property. In the long term, we
* want to do away with it. Explicitly scramble sort order if on the
* default hierarchy so that no such expectation exists in the new
* interface.
*
* Scrambling is done by swapping every two consecutive bits, which is
* non-identity one-to-one mapping which disturbs sort order sufficiently.
*/
static pid_t pid_fry(pid_t pid)
{
unsigned a = pid & 0x55555555;
unsigned b = pid & 0xAAAAAAAA;
return (a << 1) | (b >> 1);
}
static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid)
{
if (cgroup_on_dfl(cgrp))
return pid_fry(pid);
else
return pid;
}
static int cmppid(const void *a, const void *b)
{
return *(pid_t *)a - *(pid_t *)b;
}
static int fried_cmppid(const void *a, const void *b)
{
return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b);
}
static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
enum cgroup_filetype type)
{
struct cgroup_pidlist *l;
/* don't need task_nsproxy() if we're looking at ourself */
struct pid_namespace *ns = task_active_pid_ns(current);
lockdep_assert_held(&cgrp->pidlist_mutex);
list_for_each_entry(l, &cgrp->pidlists, links)
if (l->key.type == type && l->key.ns == ns)
return l;
return NULL;
}
/*
* find the appropriate pidlist for our purpose (given procs vs tasks)
* returns with the lock on that pidlist already held, and takes care
* of the use count, or returns NULL with no locks held if we're out of
* memory.
*/
static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
enum cgroup_filetype type)
{
struct cgroup_pidlist *l;
lockdep_assert_held(&cgrp->pidlist_mutex);
l = cgroup_pidlist_find(cgrp, type);
if (l)
return l;
/* entry not found; create a new one */
l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
if (!l)
return l;
2013-11-29 19:42:58 +04:00
INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
l->key.type = type;
/* don't need task_nsproxy() if we're looking at ourself */
l->key.ns = get_pid_ns(task_active_pid_ns(current));
l->owner = cgrp;
list_add(&l->links, &cgrp->pidlists);
return l;
}
/*
* Load a cgroup's pidarray with either procs' tgids or tasks' pids
*/
static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
struct cgroup_pidlist **lp)
{
pid_t *array;
int length;
int pid, n = 0; /* used for populating the array */
struct css_task_iter it;
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
struct task_struct *tsk;
struct cgroup_pidlist *l;
cgroup: load and release pidlists from seq_file start and stop respectively Currently, pidlists are reference counted from file open and release methods. This means that holding onto an open file may waste memory and reads may return data which is very stale. Both aren't critical because pidlists are keyed and shared per namespace and, well, the user isn't supposed to have large delay between open and reads. cgroup is planned to be converted to use kernfs and it'd be best if we can stick to just the seq_file operations - start, next, stop and show. This can be achieved by loading pidlist on demand from start and release with time delay from stop, so that consecutive reads don't end up reloading the pidlist on each iteration. This would remove the need for hooking into open and release while also avoiding issues with holding onto pidlist for too long. The previous patches implemented delayed release and restructured pidlist handling so that pidlists can be loaded and released from seq_file start / stop. This patch actually moves pidlist load to start and release to stop. This means that pidlist is pinned only between start and stop and may go away between two consecutive read calls if the two calls are apart by more than CGROUP_PIDLIST_DESTROY_DELAY. cgroup_pidlist_start() thus can't re-use the stored cgroup_pid_list_open_file->pidlist directly. During start, it's only used as a hint indicating whether this is the first start after open or not and pidlist is always looked up or created. pidlist_mutex locking and reference counting are moved out of pidlist_array_load() so that pidlist_array_load() can perform lookup and creation atomically. While this enlarges the area covered by pidlist_mutex, given how the lock is used, it's highly unlikely to be noticeable. v2: Refreshed on top of the updated "cgroup: introduce struct cgroup_pidlist_open_file". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-11-29 19:42:59 +04:00
lockdep_assert_held(&cgrp->pidlist_mutex);
/*
* If cgroup gets more users after we read count, we won't have
* enough space - tough. This race is indistinguishable to the
* caller from the case that the additional cgroup users didn't
* show up until sometime later on.
*/
length = cgroup_task_count(cgrp);
array = pidlist_allocate(length);
if (!array)
return -ENOMEM;
/* now, populate the array */
css_task_iter_start(&cgrp->self, &it);
while ((tsk = css_task_iter_next(&it))) {
if (unlikely(n == length))
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
break;
/* get tgid or pid for procs or tasks file respectively */
if (type == CGROUP_FILE_PROCS)
pid = task_tgid_vnr(tsk);
else
pid = task_pid_vnr(tsk);
if (pid > 0) /* make sure to only use valid results */
array[n++] = pid;
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
}
css_task_iter_end(&it);
length = n;
/* now sort & (if procs) strip out duplicates */
if (cgroup_on_dfl(cgrp))
sort(array, length, sizeof(pid_t), fried_cmppid, NULL);
else
sort(array, length, sizeof(pid_t), cmppid, NULL);
if (type == CGROUP_FILE_PROCS)
length = pidlist_uniq(array, length);
l = cgroup_pidlist_find_create(cgrp, type);
if (!l) {
pidlist_free(array);
return -ENOMEM;
}
/* store array, freeing old if necessary */
pidlist_free(l->list);
l->list = array;
l->length = length;
*lp = l;
return 0;
}
Add cgroupstats This patch is inspired by the discussion at http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263. The patch is on top of 2.6.21-mm1 with Paul's cgroups v9 patches (forward ported) This patch implements per cgroup statistics infrastructure and re-uses code from the taskstats interface. A new set of cgroup operations are registered with commands and attributes. It should be very easy to *extend* per cgroup statistics, by adding members to the cgroupstats structure. The current model for cgroupstats is a pull, a push model (to post statistics on interesting events), should be very easy to add. Currently user space requests for statistics by passing the cgroup file descriptor. Statistics about the state of all the tasks in the cgroup is returned to user space. TODO's/NOTE: This patch provides an infrastructure for implementing cgroup statistics. Based on the needs of each controller, we can incrementally add more statistics, event based support for notification of statistics, accumulation of taskstats into cgroup statistics in the future. Sample output # ./cgroupstats -C /cgroup/a sleeping 2, blocked 0, running 1, stopped 0, uninterruptible 0 # ./cgroupstats -C /cgroup/ sleeping 154, blocked 0, running 0, stopped 0, uninterruptible 0 If the approach looks good, I'll enhance and post the user space utility for the same Feedback, comments, test results are always welcome! [akpm@linux-foundation.org: build fix] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:44 +04:00
/**
* cgroupstats_build - build and fill cgroupstats
Add cgroupstats This patch is inspired by the discussion at http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263. The patch is on top of 2.6.21-mm1 with Paul's cgroups v9 patches (forward ported) This patch implements per cgroup statistics infrastructure and re-uses code from the taskstats interface. A new set of cgroup operations are registered with commands and attributes. It should be very easy to *extend* per cgroup statistics, by adding members to the cgroupstats structure. The current model for cgroupstats is a pull, a push model (to post statistics on interesting events), should be very easy to add. Currently user space requests for statistics by passing the cgroup file descriptor. Statistics about the state of all the tasks in the cgroup is returned to user space. TODO's/NOTE: This patch provides an infrastructure for implementing cgroup statistics. Based on the needs of each controller, we can incrementally add more statistics, event based support for notification of statistics, accumulation of taskstats into cgroup statistics in the future. Sample output # ./cgroupstats -C /cgroup/a sleeping 2, blocked 0, running 1, stopped 0, uninterruptible 0 # ./cgroupstats -C /cgroup/ sleeping 154, blocked 0, running 0, stopped 0, uninterruptible 0 If the approach looks good, I'll enhance and post the user space utility for the same Feedback, comments, test results are always welcome! [akpm@linux-foundation.org: build fix] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:44 +04:00
* @stats: cgroupstats to fill information into
* @dentry: A dentry entry belonging to the cgroup for which stats have
* been requested.
*
* Build and fill cgroupstats so that taskstats can export it to user
* space.
Add cgroupstats This patch is inspired by the discussion at http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263. The patch is on top of 2.6.21-mm1 with Paul's cgroups v9 patches (forward ported) This patch implements per cgroup statistics infrastructure and re-uses code from the taskstats interface. A new set of cgroup operations are registered with commands and attributes. It should be very easy to *extend* per cgroup statistics, by adding members to the cgroupstats structure. The current model for cgroupstats is a pull, a push model (to post statistics on interesting events), should be very easy to add. Currently user space requests for statistics by passing the cgroup file descriptor. Statistics about the state of all the tasks in the cgroup is returned to user space. TODO's/NOTE: This patch provides an infrastructure for implementing cgroup statistics. Based on the needs of each controller, we can incrementally add more statistics, event based support for notification of statistics, accumulation of taskstats into cgroup statistics in the future. Sample output # ./cgroupstats -C /cgroup/a sleeping 2, blocked 0, running 1, stopped 0, uninterruptible 0 # ./cgroupstats -C /cgroup/ sleeping 154, blocked 0, running 0, stopped 0, uninterruptible 0 If the approach looks good, I'll enhance and post the user space utility for the same Feedback, comments, test results are always welcome! [akpm@linux-foundation.org: build fix] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:44 +04:00
*/
int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
{
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
struct cgroup *cgrp;
struct css_task_iter it;
Add cgroupstats This patch is inspired by the discussion at http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263. The patch is on top of 2.6.21-mm1 with Paul's cgroups v9 patches (forward ported) This patch implements per cgroup statistics infrastructure and re-uses code from the taskstats interface. A new set of cgroup operations are registered with commands and attributes. It should be very easy to *extend* per cgroup statistics, by adding members to the cgroupstats structure. The current model for cgroupstats is a pull, a push model (to post statistics on interesting events), should be very easy to add. Currently user space requests for statistics by passing the cgroup file descriptor. Statistics about the state of all the tasks in the cgroup is returned to user space. TODO's/NOTE: This patch provides an infrastructure for implementing cgroup statistics. Based on the needs of each controller, we can incrementally add more statistics, event based support for notification of statistics, accumulation of taskstats into cgroup statistics in the future. Sample output # ./cgroupstats -C /cgroup/a sleeping 2, blocked 0, running 1, stopped 0, uninterruptible 0 # ./cgroupstats -C /cgroup/ sleeping 154, blocked 0, running 0, stopped 0, uninterruptible 0 If the approach looks good, I'll enhance and post the user space utility for the same Feedback, comments, test results are always welcome! [akpm@linux-foundation.org: build fix] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:44 +04:00
struct task_struct *tsk;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
/* it should be kernfs_node belonging to cgroupfs and is a directory */
if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
kernfs_type(kn) != KERNFS_DIR)
return -EINVAL;
mutex_lock(&cgroup_mutex);
Add cgroupstats This patch is inspired by the discussion at http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263. The patch is on top of 2.6.21-mm1 with Paul's cgroups v9 patches (forward ported) This patch implements per cgroup statistics infrastructure and re-uses code from the taskstats interface. A new set of cgroup operations are registered with commands and attributes. It should be very easy to *extend* per cgroup statistics, by adding members to the cgroupstats structure. The current model for cgroupstats is a pull, a push model (to post statistics on interesting events), should be very easy to add. Currently user space requests for statistics by passing the cgroup file descriptor. Statistics about the state of all the tasks in the cgroup is returned to user space. TODO's/NOTE: This patch provides an infrastructure for implementing cgroup statistics. Based on the needs of each controller, we can incrementally add more statistics, event based support for notification of statistics, accumulation of taskstats into cgroup statistics in the future. Sample output # ./cgroupstats -C /cgroup/a sleeping 2, blocked 0, running 1, stopped 0, uninterruptible 0 # ./cgroupstats -C /cgroup/ sleeping 154, blocked 0, running 0, stopped 0, uninterruptible 0 If the approach looks good, I'll enhance and post the user space utility for the same Feedback, comments, test results are always welcome! [akpm@linux-foundation.org: build fix] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:44 +04:00
/*
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
* We aren't being called from kernfs and there's no guarantee on
* @kn->priv's validity. For this and css_tryget_online_from_dir(),
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
* @kn->priv is RCU safe. Let's do the RCU dancing.
Add cgroupstats This patch is inspired by the discussion at http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263. The patch is on top of 2.6.21-mm1 with Paul's cgroups v9 patches (forward ported) This patch implements per cgroup statistics infrastructure and re-uses code from the taskstats interface. A new set of cgroup operations are registered with commands and attributes. It should be very easy to *extend* per cgroup statistics, by adding members to the cgroupstats structure. The current model for cgroupstats is a pull, a push model (to post statistics on interesting events), should be very easy to add. Currently user space requests for statistics by passing the cgroup file descriptor. Statistics about the state of all the tasks in the cgroup is returned to user space. TODO's/NOTE: This patch provides an infrastructure for implementing cgroup statistics. Based on the needs of each controller, we can incrementally add more statistics, event based support for notification of statistics, accumulation of taskstats into cgroup statistics in the future. Sample output # ./cgroupstats -C /cgroup/a sleeping 2, blocked 0, running 1, stopped 0, uninterruptible 0 # ./cgroupstats -C /cgroup/ sleeping 154, blocked 0, running 0, stopped 0, uninterruptible 0 If the approach looks good, I'll enhance and post the user space utility for the same Feedback, comments, test results are always welcome! [akpm@linux-foundation.org: build fix] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:44 +04:00
*/
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
rcu_read_lock();
cgrp = rcu_dereference(kn->priv);
if (!cgrp || cgroup_is_dead(cgrp)) {
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
rcu_read_unlock();
mutex_unlock(&cgroup_mutex);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
return -ENOENT;
}
rcu_read_unlock();
Add cgroupstats This patch is inspired by the discussion at http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263. The patch is on top of 2.6.21-mm1 with Paul's cgroups v9 patches (forward ported) This patch implements per cgroup statistics infrastructure and re-uses code from the taskstats interface. A new set of cgroup operations are registered with commands and attributes. It should be very easy to *extend* per cgroup statistics, by adding members to the cgroupstats structure. The current model for cgroupstats is a pull, a push model (to post statistics on interesting events), should be very easy to add. Currently user space requests for statistics by passing the cgroup file descriptor. Statistics about the state of all the tasks in the cgroup is returned to user space. TODO's/NOTE: This patch provides an infrastructure for implementing cgroup statistics. Based on the needs of each controller, we can incrementally add more statistics, event based support for notification of statistics, accumulation of taskstats into cgroup statistics in the future. Sample output # ./cgroupstats -C /cgroup/a sleeping 2, blocked 0, running 1, stopped 0, uninterruptible 0 # ./cgroupstats -C /cgroup/ sleeping 154, blocked 0, running 0, stopped 0, uninterruptible 0 If the approach looks good, I'll enhance and post the user space utility for the same Feedback, comments, test results are always welcome! [akpm@linux-foundation.org: build fix] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:44 +04:00
css_task_iter_start(&cgrp->self, &it);
while ((tsk = css_task_iter_next(&it))) {
Add cgroupstats This patch is inspired by the discussion at http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263. The patch is on top of 2.6.21-mm1 with Paul's cgroups v9 patches (forward ported) This patch implements per cgroup statistics infrastructure and re-uses code from the taskstats interface. A new set of cgroup operations are registered with commands and attributes. It should be very easy to *extend* per cgroup statistics, by adding members to the cgroupstats structure. The current model for cgroupstats is a pull, a push model (to post statistics on interesting events), should be very easy to add. Currently user space requests for statistics by passing the cgroup file descriptor. Statistics about the state of all the tasks in the cgroup is returned to user space. TODO's/NOTE: This patch provides an infrastructure for implementing cgroup statistics. Based on the needs of each controller, we can incrementally add more statistics, event based support for notification of statistics, accumulation of taskstats into cgroup statistics in the future. Sample output # ./cgroupstats -C /cgroup/a sleeping 2, blocked 0, running 1, stopped 0, uninterruptible 0 # ./cgroupstats -C /cgroup/ sleeping 154, blocked 0, running 0, stopped 0, uninterruptible 0 If the approach looks good, I'll enhance and post the user space utility for the same Feedback, comments, test results are always welcome! [akpm@linux-foundation.org: build fix] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:44 +04:00
switch (tsk->state) {
case TASK_RUNNING:
stats->nr_running++;
break;
case TASK_INTERRUPTIBLE:
stats->nr_sleeping++;
break;
case TASK_UNINTERRUPTIBLE:
stats->nr_uninterruptible++;
break;
case TASK_STOPPED:
stats->nr_stopped++;
break;
default:
if (delayacct_is_task_waiting_on_io(tsk))
stats->nr_io_wait++;
break;
}
}
css_task_iter_end(&it);
Add cgroupstats This patch is inspired by the discussion at http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263. The patch is on top of 2.6.21-mm1 with Paul's cgroups v9 patches (forward ported) This patch implements per cgroup statistics infrastructure and re-uses code from the taskstats interface. A new set of cgroup operations are registered with commands and attributes. It should be very easy to *extend* per cgroup statistics, by adding members to the cgroupstats structure. The current model for cgroupstats is a pull, a push model (to post statistics on interesting events), should be very easy to add. Currently user space requests for statistics by passing the cgroup file descriptor. Statistics about the state of all the tasks in the cgroup is returned to user space. TODO's/NOTE: This patch provides an infrastructure for implementing cgroup statistics. Based on the needs of each controller, we can incrementally add more statistics, event based support for notification of statistics, accumulation of taskstats into cgroup statistics in the future. Sample output # ./cgroupstats -C /cgroup/a sleeping 2, blocked 0, running 1, stopped 0, uninterruptible 0 # ./cgroupstats -C /cgroup/ sleeping 154, blocked 0, running 0, stopped 0, uninterruptible 0 If the approach looks good, I'll enhance and post the user space utility for the same Feedback, comments, test results are always welcome! [akpm@linux-foundation.org: build fix] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:44 +04:00
mutex_unlock(&cgroup_mutex);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
return 0;
Add cgroupstats This patch is inspired by the discussion at http://lkml.org/lkml/2007/4/11/187 and implements per cgroup statistics as suggested by Andrew Morton in http://lkml.org/lkml/2007/4/11/263. The patch is on top of 2.6.21-mm1 with Paul's cgroups v9 patches (forward ported) This patch implements per cgroup statistics infrastructure and re-uses code from the taskstats interface. A new set of cgroup operations are registered with commands and attributes. It should be very easy to *extend* per cgroup statistics, by adding members to the cgroupstats structure. The current model for cgroupstats is a pull, a push model (to post statistics on interesting events), should be very easy to add. Currently user space requests for statistics by passing the cgroup file descriptor. Statistics about the state of all the tasks in the cgroup is returned to user space. TODO's/NOTE: This patch provides an infrastructure for implementing cgroup statistics. Based on the needs of each controller, we can incrementally add more statistics, event based support for notification of statistics, accumulation of taskstats into cgroup statistics in the future. Sample output # ./cgroupstats -C /cgroup/a sleeping 2, blocked 0, running 1, stopped 0, uninterruptible 0 # ./cgroupstats -C /cgroup/ sleeping 154, blocked 0, running 0, stopped 0, uninterruptible 0 If the approach looks good, I'll enhance and post the user space utility for the same Feedback, comments, test results are always welcome! [akpm@linux-foundation.org: build fix] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:44 +04:00
}
cgroups: revert "cgroups: fix pid namespace bug" The following series adds a "cgroup.procs" file to each cgroup that reports unique tgids rather than pids, and allows all threads in a threadgroup to be atomically moved to a new cgroup. The subsystem "attach" interface is modified to support attaching whole threadgroups at a time, which could introduce potential problems if any subsystem were to need to access the old cgroup of every thread being moved. The attach interface may need to be revised if this becomes the case. Also added is functionality for read/write locking all CLONE_THREAD fork()ing within a threadgroup, by means of an rwsem that lives in the sighand_struct, for per-threadgroup-ness and also for sharing a cacheline with the sighand's atomic count. This scheme should introduce no extra overhead in the fork path when there's no contention. The final patch reveals potential for a race when forking before a subsystem's attach function is called - one potential solution in case any subsystem has this problem is to hang on to the group's fork mutex through the attach() calls, though no subsystem yet demonstrates need for an extended critical section. This patch: Revert commit 096b7fe012d66ed55e98bc8022405ede0cc80e96 Author: Li Zefan <lizf@cn.fujitsu.com> AuthorDate: Wed Jul 29 15:04:04 2009 -0700 Commit: Linus Torvalds <torvalds@linux-foundation.org> CommitDate: Wed Jul 29 19:10:35 2009 -0700 cgroups: fix pid namespace bug This is in preparation for some clashing cgroups changes that subsume the original commit's functionaliy. The original commit fixed a pid namespace bug which Ben Blum fixed independently (in the same way, but with different code) as part of a series of patches. I played around with trying to reconcile Ben's patch series with Li's patch, but concluded that it was simpler to just revert Li's, given that Ben's patch series contained essentially the same fix. Signed-off-by: Paul Menage <menage@google.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-24 02:56:25 +04:00
/*
* seq_file methods for the tasks/procs files. The seq_file position is the
* next pid to display; the seq_file iterator is a pointer to the pid
* in the cgroup->l->list array.
*/
static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
{
/*
* Initially we receive a position value that corresponds to
* one more than the last pid shown (or 0 on the first call or
* after a seek to the start). Use a binary-search to find the
* next pid to display, if any
*/
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct kernfs_open_file *of = s->private;
struct cgroup *cgrp = seq_css(s)->cgroup;
cgroup: load and release pidlists from seq_file start and stop respectively Currently, pidlists are reference counted from file open and release methods. This means that holding onto an open file may waste memory and reads may return data which is very stale. Both aren't critical because pidlists are keyed and shared per namespace and, well, the user isn't supposed to have large delay between open and reads. cgroup is planned to be converted to use kernfs and it'd be best if we can stick to just the seq_file operations - start, next, stop and show. This can be achieved by loading pidlist on demand from start and release with time delay from stop, so that consecutive reads don't end up reloading the pidlist on each iteration. This would remove the need for hooking into open and release while also avoiding issues with holding onto pidlist for too long. The previous patches implemented delayed release and restructured pidlist handling so that pidlists can be loaded and released from seq_file start / stop. This patch actually moves pidlist load to start and release to stop. This means that pidlist is pinned only between start and stop and may go away between two consecutive read calls if the two calls are apart by more than CGROUP_PIDLIST_DESTROY_DELAY. cgroup_pidlist_start() thus can't re-use the stored cgroup_pid_list_open_file->pidlist directly. During start, it's only used as a hint indicating whether this is the first start after open or not and pidlist is always looked up or created. pidlist_mutex locking and reference counting are moved out of pidlist_array_load() so that pidlist_array_load() can perform lookup and creation atomically. While this enlarges the area covered by pidlist_mutex, given how the lock is used, it's highly unlikely to be noticeable. v2: Refreshed on top of the updated "cgroup: introduce struct cgroup_pidlist_open_file". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-11-29 19:42:59 +04:00
struct cgroup_pidlist *l;
enum cgroup_filetype type = seq_cft(s)->private;
int index = 0, pid = *pos;
cgroup: load and release pidlists from seq_file start and stop respectively Currently, pidlists are reference counted from file open and release methods. This means that holding onto an open file may waste memory and reads may return data which is very stale. Both aren't critical because pidlists are keyed and shared per namespace and, well, the user isn't supposed to have large delay between open and reads. cgroup is planned to be converted to use kernfs and it'd be best if we can stick to just the seq_file operations - start, next, stop and show. This can be achieved by loading pidlist on demand from start and release with time delay from stop, so that consecutive reads don't end up reloading the pidlist on each iteration. This would remove the need for hooking into open and release while also avoiding issues with holding onto pidlist for too long. The previous patches implemented delayed release and restructured pidlist handling so that pidlists can be loaded and released from seq_file start / stop. This patch actually moves pidlist load to start and release to stop. This means that pidlist is pinned only between start and stop and may go away between two consecutive read calls if the two calls are apart by more than CGROUP_PIDLIST_DESTROY_DELAY. cgroup_pidlist_start() thus can't re-use the stored cgroup_pid_list_open_file->pidlist directly. During start, it's only used as a hint indicating whether this is the first start after open or not and pidlist is always looked up or created. pidlist_mutex locking and reference counting are moved out of pidlist_array_load() so that pidlist_array_load() can perform lookup and creation atomically. While this enlarges the area covered by pidlist_mutex, given how the lock is used, it's highly unlikely to be noticeable. v2: Refreshed on top of the updated "cgroup: introduce struct cgroup_pidlist_open_file". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-11-29 19:42:59 +04:00
int *iter, ret;
mutex_lock(&cgrp->pidlist_mutex);
/*
* !NULL @of->priv indicates that this isn't the first start()
cgroup: load and release pidlists from seq_file start and stop respectively Currently, pidlists are reference counted from file open and release methods. This means that holding onto an open file may waste memory and reads may return data which is very stale. Both aren't critical because pidlists are keyed and shared per namespace and, well, the user isn't supposed to have large delay between open and reads. cgroup is planned to be converted to use kernfs and it'd be best if we can stick to just the seq_file operations - start, next, stop and show. This can be achieved by loading pidlist on demand from start and release with time delay from stop, so that consecutive reads don't end up reloading the pidlist on each iteration. This would remove the need for hooking into open and release while also avoiding issues with holding onto pidlist for too long. The previous patches implemented delayed release and restructured pidlist handling so that pidlists can be loaded and released from seq_file start / stop. This patch actually moves pidlist load to start and release to stop. This means that pidlist is pinned only between start and stop and may go away between two consecutive read calls if the two calls are apart by more than CGROUP_PIDLIST_DESTROY_DELAY. cgroup_pidlist_start() thus can't re-use the stored cgroup_pid_list_open_file->pidlist directly. During start, it's only used as a hint indicating whether this is the first start after open or not and pidlist is always looked up or created. pidlist_mutex locking and reference counting are moved out of pidlist_array_load() so that pidlist_array_load() can perform lookup and creation atomically. While this enlarges the area covered by pidlist_mutex, given how the lock is used, it's highly unlikely to be noticeable. v2: Refreshed on top of the updated "cgroup: introduce struct cgroup_pidlist_open_file". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-11-29 19:42:59 +04:00
* after open. If the matching pidlist is around, we can use that.
* Look for it. Note that @of->priv can't be used directly. It
cgroup: load and release pidlists from seq_file start and stop respectively Currently, pidlists are reference counted from file open and release methods. This means that holding onto an open file may waste memory and reads may return data which is very stale. Both aren't critical because pidlists are keyed and shared per namespace and, well, the user isn't supposed to have large delay between open and reads. cgroup is planned to be converted to use kernfs and it'd be best if we can stick to just the seq_file operations - start, next, stop and show. This can be achieved by loading pidlist on demand from start and release with time delay from stop, so that consecutive reads don't end up reloading the pidlist on each iteration. This would remove the need for hooking into open and release while also avoiding issues with holding onto pidlist for too long. The previous patches implemented delayed release and restructured pidlist handling so that pidlists can be loaded and released from seq_file start / stop. This patch actually moves pidlist load to start and release to stop. This means that pidlist is pinned only between start and stop and may go away between two consecutive read calls if the two calls are apart by more than CGROUP_PIDLIST_DESTROY_DELAY. cgroup_pidlist_start() thus can't re-use the stored cgroup_pid_list_open_file->pidlist directly. During start, it's only used as a hint indicating whether this is the first start after open or not and pidlist is always looked up or created. pidlist_mutex locking and reference counting are moved out of pidlist_array_load() so that pidlist_array_load() can perform lookup and creation atomically. While this enlarges the area covered by pidlist_mutex, given how the lock is used, it's highly unlikely to be noticeable. v2: Refreshed on top of the updated "cgroup: introduce struct cgroup_pidlist_open_file". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-11-29 19:42:59 +04:00
* could already have been destroyed.
*/
if (of->priv)
of->priv = cgroup_pidlist_find(cgrp, type);
cgroup: load and release pidlists from seq_file start and stop respectively Currently, pidlists are reference counted from file open and release methods. This means that holding onto an open file may waste memory and reads may return data which is very stale. Both aren't critical because pidlists are keyed and shared per namespace and, well, the user isn't supposed to have large delay between open and reads. cgroup is planned to be converted to use kernfs and it'd be best if we can stick to just the seq_file operations - start, next, stop and show. This can be achieved by loading pidlist on demand from start and release with time delay from stop, so that consecutive reads don't end up reloading the pidlist on each iteration. This would remove the need for hooking into open and release while also avoiding issues with holding onto pidlist for too long. The previous patches implemented delayed release and restructured pidlist handling so that pidlists can be loaded and released from seq_file start / stop. This patch actually moves pidlist load to start and release to stop. This means that pidlist is pinned only between start and stop and may go away between two consecutive read calls if the two calls are apart by more than CGROUP_PIDLIST_DESTROY_DELAY. cgroup_pidlist_start() thus can't re-use the stored cgroup_pid_list_open_file->pidlist directly. During start, it's only used as a hint indicating whether this is the first start after open or not and pidlist is always looked up or created. pidlist_mutex locking and reference counting are moved out of pidlist_array_load() so that pidlist_array_load() can perform lookup and creation atomically. While this enlarges the area covered by pidlist_mutex, given how the lock is used, it's highly unlikely to be noticeable. v2: Refreshed on top of the updated "cgroup: introduce struct cgroup_pidlist_open_file". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-11-29 19:42:59 +04:00
/*
* Either this is the first start() after open or the matching
* pidlist has been destroyed inbetween. Create a new one.
*/
if (!of->priv) {
ret = pidlist_array_load(cgrp, type,
(struct cgroup_pidlist **)&of->priv);
cgroup: load and release pidlists from seq_file start and stop respectively Currently, pidlists are reference counted from file open and release methods. This means that holding onto an open file may waste memory and reads may return data which is very stale. Both aren't critical because pidlists are keyed and shared per namespace and, well, the user isn't supposed to have large delay between open and reads. cgroup is planned to be converted to use kernfs and it'd be best if we can stick to just the seq_file operations - start, next, stop and show. This can be achieved by loading pidlist on demand from start and release with time delay from stop, so that consecutive reads don't end up reloading the pidlist on each iteration. This would remove the need for hooking into open and release while also avoiding issues with holding onto pidlist for too long. The previous patches implemented delayed release and restructured pidlist handling so that pidlists can be loaded and released from seq_file start / stop. This patch actually moves pidlist load to start and release to stop. This means that pidlist is pinned only between start and stop and may go away between two consecutive read calls if the two calls are apart by more than CGROUP_PIDLIST_DESTROY_DELAY. cgroup_pidlist_start() thus can't re-use the stored cgroup_pid_list_open_file->pidlist directly. During start, it's only used as a hint indicating whether this is the first start after open or not and pidlist is always looked up or created. pidlist_mutex locking and reference counting are moved out of pidlist_array_load() so that pidlist_array_load() can perform lookup and creation atomically. While this enlarges the area covered by pidlist_mutex, given how the lock is used, it's highly unlikely to be noticeable. v2: Refreshed on top of the updated "cgroup: introduce struct cgroup_pidlist_open_file". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-11-29 19:42:59 +04:00
if (ret)
return ERR_PTR(ret);
}
l = of->priv;
if (pid) {
int end = l->length;
while (index < end) {
int mid = (index + end) / 2;
if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) {
index = mid;
break;
} else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid)
index = mid + 1;
else
end = mid;
}
}
/* If we're off the end of the array, we're done */
if (index >= l->length)
return NULL;
/* Update the abstract position to be the actual pid that we found */
iter = l->list + index;
*pos = cgroup_pid_fry(cgrp, *iter);
return iter;
}
static void cgroup_pidlist_stop(struct seq_file *s, void *v)
{
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct kernfs_open_file *of = s->private;
struct cgroup_pidlist *l = of->priv;
if (l)
mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
CGROUP_PIDLIST_DESTROY_DELAY);
mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
}
static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
{
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct kernfs_open_file *of = s->private;
struct cgroup_pidlist *l = of->priv;
pid_t *p = v;
pid_t *end = l->list + l->length;
/*
* Advance to the next pid in the array. If this goes off the
* end, we're done
*/
p++;
if (p >= end) {
return NULL;
} else {
*pos = cgroup_pid_fry(seq_css(s)->cgroup, *p);
return p;
}
}
static int cgroup_pidlist_show(struct seq_file *s, void *v)
{
seq_printf(s, "%d\n", *(int *)v);
return 0;
}
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
struct cftype *cft)
{
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
return notify_on_release(css->cgroup);
}
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
{
if (val)
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
else
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
return 0;
}
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
struct cftype *cft)
cgroup: add clone_children control file The ns_cgroup is a control group interacting with the namespaces. When a new namespace is created, a corresponding cgroup is automatically created too. The cgroup name is the pid of the process who did 'unshare' or the child of 'clone'. This cgroup is tied with the namespace because it prevents a process to escape the control group and use the post_clone callback, so the child cgroup inherits the values of the parent cgroup. Unfortunately, the more we use this cgroup and the more we are facing problems with it: (1) when a process unshares, the cgroup name may conflict with a previous cgroup with the same pid, so unshare or clone return -EEXIST (2) the cgroup creation is out of control because there may have an application creating several namespaces where the system will automatically create several cgroups in his back and let them on the cgroupfs (eg. a vrf based on the network namespace). (3) the mix of (1) and (2) force an administrator to regularly check and clean these cgroups. This patchset removes the ns_cgroup by adding a new flag to the cgroup and the cgroupfs mount option. It enables the copy of the parent cgroup when a child cgroup is created. We can then safely remove the ns_cgroup as this flag brings a compatibility. We have now to manually create and add the task to a cgroup, which is consistent with the cgroup framework. This patch: Sent as an answer to a previous thread around the ns_cgroup. https://lists.linux-foundation.org/pipermail/containers/2009-June/018627.html It adds a control file 'clone_children' for a cgroup. This control file is a boolean specifying if the child cgroup should be a clone of the parent cgroup or not. The default value is 'false'. This flag makes the child cgroup to call the post_clone callback of all the subsystem, if it is available. At present, the cpuset is the only one which had implemented the post_clone callback. The option can be set at mount time by specifying the 'clone_children' mount option. Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Paul Menage <menage@google.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:35 +04:00
{
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
cgroup: add clone_children control file The ns_cgroup is a control group interacting with the namespaces. When a new namespace is created, a corresponding cgroup is automatically created too. The cgroup name is the pid of the process who did 'unshare' or the child of 'clone'. This cgroup is tied with the namespace because it prevents a process to escape the control group and use the post_clone callback, so the child cgroup inherits the values of the parent cgroup. Unfortunately, the more we use this cgroup and the more we are facing problems with it: (1) when a process unshares, the cgroup name may conflict with a previous cgroup with the same pid, so unshare or clone return -EEXIST (2) the cgroup creation is out of control because there may have an application creating several namespaces where the system will automatically create several cgroups in his back and let them on the cgroupfs (eg. a vrf based on the network namespace). (3) the mix of (1) and (2) force an administrator to regularly check and clean these cgroups. This patchset removes the ns_cgroup by adding a new flag to the cgroup and the cgroupfs mount option. It enables the copy of the parent cgroup when a child cgroup is created. We can then safely remove the ns_cgroup as this flag brings a compatibility. We have now to manually create and add the task to a cgroup, which is consistent with the cgroup framework. This patch: Sent as an answer to a previous thread around the ns_cgroup. https://lists.linux-foundation.org/pipermail/containers/2009-June/018627.html It adds a control file 'clone_children' for a cgroup. This control file is a boolean specifying if the child cgroup should be a clone of the parent cgroup or not. The default value is 'false'. This flag makes the child cgroup to call the post_clone callback of all the subsystem, if it is available. At present, the cpuset is the only one which had implemented the post_clone callback. The option can be set at mount time by specifying the 'clone_children' mount option. Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Paul Menage <menage@google.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:35 +04:00
}
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
struct cftype *cft, u64 val)
cgroup: add clone_children control file The ns_cgroup is a control group interacting with the namespaces. When a new namespace is created, a corresponding cgroup is automatically created too. The cgroup name is the pid of the process who did 'unshare' or the child of 'clone'. This cgroup is tied with the namespace because it prevents a process to escape the control group and use the post_clone callback, so the child cgroup inherits the values of the parent cgroup. Unfortunately, the more we use this cgroup and the more we are facing problems with it: (1) when a process unshares, the cgroup name may conflict with a previous cgroup with the same pid, so unshare or clone return -EEXIST (2) the cgroup creation is out of control because there may have an application creating several namespaces where the system will automatically create several cgroups in his back and let them on the cgroupfs (eg. a vrf based on the network namespace). (3) the mix of (1) and (2) force an administrator to regularly check and clean these cgroups. This patchset removes the ns_cgroup by adding a new flag to the cgroup and the cgroupfs mount option. It enables the copy of the parent cgroup when a child cgroup is created. We can then safely remove the ns_cgroup as this flag brings a compatibility. We have now to manually create and add the task to a cgroup, which is consistent with the cgroup framework. This patch: Sent as an answer to a previous thread around the ns_cgroup. https://lists.linux-foundation.org/pipermail/containers/2009-June/018627.html It adds a control file 'clone_children' for a cgroup. This control file is a boolean specifying if the child cgroup should be a clone of the parent cgroup or not. The default value is 'false'. This flag makes the child cgroup to call the post_clone callback of all the subsystem, if it is available. At present, the cpuset is the only one which had implemented the post_clone callback. The option can be set at mount time by specifying the 'clone_children' mount option. Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Paul Menage <menage@google.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:35 +04:00
{
if (val)
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
cgroup: add clone_children control file The ns_cgroup is a control group interacting with the namespaces. When a new namespace is created, a corresponding cgroup is automatically created too. The cgroup name is the pid of the process who did 'unshare' or the child of 'clone'. This cgroup is tied with the namespace because it prevents a process to escape the control group and use the post_clone callback, so the child cgroup inherits the values of the parent cgroup. Unfortunately, the more we use this cgroup and the more we are facing problems with it: (1) when a process unshares, the cgroup name may conflict with a previous cgroup with the same pid, so unshare or clone return -EEXIST (2) the cgroup creation is out of control because there may have an application creating several namespaces where the system will automatically create several cgroups in his back and let them on the cgroupfs (eg. a vrf based on the network namespace). (3) the mix of (1) and (2) force an administrator to regularly check and clean these cgroups. This patchset removes the ns_cgroup by adding a new flag to the cgroup and the cgroupfs mount option. It enables the copy of the parent cgroup when a child cgroup is created. We can then safely remove the ns_cgroup as this flag brings a compatibility. We have now to manually create and add the task to a cgroup, which is consistent with the cgroup framework. This patch: Sent as an answer to a previous thread around the ns_cgroup. https://lists.linux-foundation.org/pipermail/containers/2009-June/018627.html It adds a control file 'clone_children' for a cgroup. This control file is a boolean specifying if the child cgroup should be a clone of the parent cgroup or not. The default value is 'false'. This flag makes the child cgroup to call the post_clone callback of all the subsystem, if it is available. At present, the cpuset is the only one which had implemented the post_clone callback. The option can be set at mount time by specifying the 'clone_children' mount option. Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Paul Menage <menage@google.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:35 +04:00
else
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
cgroup: add clone_children control file The ns_cgroup is a control group interacting with the namespaces. When a new namespace is created, a corresponding cgroup is automatically created too. The cgroup name is the pid of the process who did 'unshare' or the child of 'clone'. This cgroup is tied with the namespace because it prevents a process to escape the control group and use the post_clone callback, so the child cgroup inherits the values of the parent cgroup. Unfortunately, the more we use this cgroup and the more we are facing problems with it: (1) when a process unshares, the cgroup name may conflict with a previous cgroup with the same pid, so unshare or clone return -EEXIST (2) the cgroup creation is out of control because there may have an application creating several namespaces where the system will automatically create several cgroups in his back and let them on the cgroupfs (eg. a vrf based on the network namespace). (3) the mix of (1) and (2) force an administrator to regularly check and clean these cgroups. This patchset removes the ns_cgroup by adding a new flag to the cgroup and the cgroupfs mount option. It enables the copy of the parent cgroup when a child cgroup is created. We can then safely remove the ns_cgroup as this flag brings a compatibility. We have now to manually create and add the task to a cgroup, which is consistent with the cgroup framework. This patch: Sent as an answer to a previous thread around the ns_cgroup. https://lists.linux-foundation.org/pipermail/containers/2009-June/018627.html It adds a control file 'clone_children' for a cgroup. This control file is a boolean specifying if the child cgroup should be a clone of the parent cgroup or not. The default value is 'false'. This flag makes the child cgroup to call the post_clone callback of all the subsystem, if it is available. At present, the cpuset is the only one which had implemented the post_clone callback. The option can be set at mount time by specifying the 'clone_children' mount option. Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Paul Menage <menage@google.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:35 +04:00
return 0;
}
/* cgroup core interface files for the default hierarchy */
static struct cftype cgroup_dfl_base_files[] = {
{
.name = "cgroup.procs",
.file_offset = offsetof(struct cgroup, procs_file),
.seq_start = cgroup_pidlist_start,
.seq_next = cgroup_pidlist_next,
.seq_stop = cgroup_pidlist_stop,
.seq_show = cgroup_pidlist_show,
.private = CGROUP_FILE_PROCS,
.write = cgroup_procs_write,
},
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
{
.name = "cgroup.controllers",
.flags = CFTYPE_ONLY_ON_ROOT,
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
.seq_show = cgroup_root_controllers_show,
},
{
.name = "cgroup.controllers",
.flags = CFTYPE_NOT_ON_ROOT,
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
.seq_show = cgroup_controllers_show,
},
{
.name = "cgroup.subtree_control",
.seq_show = cgroup_subtree_control_show,
.write = cgroup_subtree_control_write,
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
},
cgroup: implement cgroup.populated for the default hierarchy cgroup users often need a way to determine when a cgroup's subhierarchy becomes empty so that it can be cleaned up. cgroup currently provides release_agent for it; unfortunately, this mechanism is riddled with issues. * It delivers events by forking and execing a userland binary specified as the release_agent. This is a long deprecated method of notification delivery. It's extremely heavy, slow and cumbersome to integrate with larger infrastructure. * There is single monitoring point at the root. There's no way to delegate management of a subtree. * The event isn't recursive. It triggers when a cgroup doesn't have any tasks or child cgroups. Events for internal nodes trigger only after all children are removed. This again makes it impossible to delegate management of a subtree. * Events are filtered from the kernel side. "notify_on_release" file is used to subscribe to or suppress release event. This is unnecessarily complicated and probably done this way because event delivery itself was expensive. This patch implements interface file "cgroup.populated" which can be used to monitor whether the cgroup's subhierarchy has tasks in it or not. Its value is 0 if there is no task in the cgroup and its descendants; otherwise, 1, and kernfs_notify() notificaiton is triggers when the value changes, which can be monitored through poll and [di]notify. This is a lot ligther and simpler and trivially allows delegating management of subhierarchy - subhierarchy monitoring can block further propgation simply by putting itself or another process in the root of the subhierarchy and monitor events that it's interested in from there without interfering with monitoring higher in the tree. v2: Patch description updated as per Serge. v3: "cgroup.subtree_populated" renamed to "cgroup.populated". The subtree_ prefix was a bit confusing because "cgroup.subtree_control" uses it to denote the tree rooted at the cgroup sans the cgroup itself while the populated state includes the cgroup itself. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Lennart Poettering <lennart@poettering.net>
2014-04-26 02:28:02 +04:00
{
.name = "cgroup.events",
.flags = CFTYPE_NOT_ON_ROOT,
.file_offset = offsetof(struct cgroup, events_file),
.seq_show = cgroup_events_show,
cgroup: implement cgroup.populated for the default hierarchy cgroup users often need a way to determine when a cgroup's subhierarchy becomes empty so that it can be cleaned up. cgroup currently provides release_agent for it; unfortunately, this mechanism is riddled with issues. * It delivers events by forking and execing a userland binary specified as the release_agent. This is a long deprecated method of notification delivery. It's extremely heavy, slow and cumbersome to integrate with larger infrastructure. * There is single monitoring point at the root. There's no way to delegate management of a subtree. * The event isn't recursive. It triggers when a cgroup doesn't have any tasks or child cgroups. Events for internal nodes trigger only after all children are removed. This again makes it impossible to delegate management of a subtree. * Events are filtered from the kernel side. "notify_on_release" file is used to subscribe to or suppress release event. This is unnecessarily complicated and probably done this way because event delivery itself was expensive. This patch implements interface file "cgroup.populated" which can be used to monitor whether the cgroup's subhierarchy has tasks in it or not. Its value is 0 if there is no task in the cgroup and its descendants; otherwise, 1, and kernfs_notify() notificaiton is triggers when the value changes, which can be monitored through poll and [di]notify. This is a lot ligther and simpler and trivially allows delegating management of subhierarchy - subhierarchy monitoring can block further propgation simply by putting itself or another process in the root of the subhierarchy and monitor events that it's interested in from there without interfering with monitoring higher in the tree. v2: Patch description updated as per Serge. v3: "cgroup.subtree_populated" renamed to "cgroup.populated". The subtree_ prefix was a bit confusing because "cgroup.subtree_control" uses it to denote the tree rooted at the cgroup sans the cgroup itself while the populated state includes the cgroup itself. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge Hallyn <serge.hallyn@ubuntu.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Lennart Poettering <lennart@poettering.net>
2014-04-26 02:28:02 +04:00
},
{ } /* terminate */
};
/* cgroup core interface files for the legacy hierarchies */
static struct cftype cgroup_legacy_base_files[] = {
{
.name = "cgroup.procs",
.seq_start = cgroup_pidlist_start,
.seq_next = cgroup_pidlist_next,
.seq_stop = cgroup_pidlist_stop,
.seq_show = cgroup_pidlist_show,
.private = CGROUP_FILE_PROCS,
.write = cgroup_procs_write,
},
{
.name = "cgroup.clone_children",
.read_u64 = cgroup_clone_children_read,
.write_u64 = cgroup_clone_children_write,
},
{
.name = "cgroup.sane_behavior",
.flags = CFTYPE_ONLY_ON_ROOT,
.seq_show = cgroup_sane_behavior_show,
},
{
.name = "tasks",
.seq_start = cgroup_pidlist_start,
.seq_next = cgroup_pidlist_next,
.seq_stop = cgroup_pidlist_stop,
.seq_show = cgroup_pidlist_show,
.private = CGROUP_FILE_TASKS,
.write = cgroup_tasks_write,
},
{
.name = "notify_on_release",
.read_u64 = cgroup_read_notify_on_release,
.write_u64 = cgroup_write_notify_on_release,
},
{
.name = "release_agent",
.flags = CFTYPE_ONLY_ON_ROOT,
.seq_show = cgroup_release_agent_show,
.write = cgroup_release_agent_write,
.max_write_len = PATH_MAX - 1,
},
{ } /* terminate */
};
cgroup: RCU protect each cgroup_subsys_state release With the planned unified hierarchy, individual css's will be created and destroyed dynamically across the lifetime of a cgroup. To enable such usages, css destruction is being decoupled from cgroup destruction. Most of the destruction path has been decoupled but the actual free of css still depends on cgroup free path. When all css refs are drained, css_release() kicks off css_free_work_fn() which puts the cgroup. When the cgroup refcnt reaches zero, cgroup_diput() is invoked which in turn schedules RCU free of the cgroup. After a grace period, all css's are freed along with the cgroup itself. This patch moves the RCU grace period and css freeing from cgroup release path to css release path. css_release(), instead of kicking off css_free_work_fn() directly, schedules RCU callback css_free_rcu_fn() which in turn kicks off css_free_work_fn() after a RCU grace period. css_free_work_fn() is updated to free the css directly. The five-way punting - percpu ref kill confirmation, a work item, percpu ref release, RCU grace period, and again a work item - is quite hairy but the work items are there only to provide process context and the actual sequence is kill confirm -> release -> RCU free, which isn't simple but not too crazy. This removes cgroup_css() usage after offline_css() allowing clearing cgroup->subsys[] from offline_css(), which makes it consistent with online_css() and brings it closer to proper lifetime management for individual css's. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-08-14 04:22:51 +04:00
/*
* css destruction is four-stage process.
*
* 1. Destruction starts. Killing of the percpu_ref is initiated.
* Implemented in kill_css().
*
* 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
* and thus css_tryget_online() is guaranteed to fail, the css can be
* offlined by invoking offline_css(). After offlining, the base ref is
* put. Implemented in css_killed_work_fn().
cgroup: RCU protect each cgroup_subsys_state release With the planned unified hierarchy, individual css's will be created and destroyed dynamically across the lifetime of a cgroup. To enable such usages, css destruction is being decoupled from cgroup destruction. Most of the destruction path has been decoupled but the actual free of css still depends on cgroup free path. When all css refs are drained, css_release() kicks off css_free_work_fn() which puts the cgroup. When the cgroup refcnt reaches zero, cgroup_diput() is invoked which in turn schedules RCU free of the cgroup. After a grace period, all css's are freed along with the cgroup itself. This patch moves the RCU grace period and css freeing from cgroup release path to css release path. css_release(), instead of kicking off css_free_work_fn() directly, schedules RCU callback css_free_rcu_fn() which in turn kicks off css_free_work_fn() after a RCU grace period. css_free_work_fn() is updated to free the css directly. The five-way punting - percpu ref kill confirmation, a work item, percpu ref release, RCU grace period, and again a work item - is quite hairy but the work items are there only to provide process context and the actual sequence is kill confirm -> release -> RCU free, which isn't simple but not too crazy. This removes cgroup_css() usage after offline_css() allowing clearing cgroup->subsys[] from offline_css(), which makes it consistent with online_css() and brings it closer to proper lifetime management for individual css's. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-08-14 04:22:51 +04:00
*
* 3. When the percpu_ref reaches zero, the only possible remaining
* accessors are inside RCU read sections. css_release() schedules the
* RCU callback.
*
* 4. After the grace period, the css can be freed. Implemented in
* css_free_work_fn().
*
* It is actually hairier because both step 2 and 4 require process context
* and thus involve punting to css->destroy_work adding two additional
* steps to the already complex sequence.
*/
static void css_free_work_fn(struct work_struct *work)
cgroup: make css->refcnt clearing on cgroup removal optional Currently, cgroup removal tries to drain all css references. If there are active css references, the removal logic waits and retries ->pre_detroy() until either all refs drop to zero or removal is cancelled. This semantics is unusual and adds non-trivial complexity to cgroup core and IMHO is fundamentally misguided in that it couples internal implementation details (references to internal data structure) with externally visible operation (rmdir). To userland, this is a behavior peculiarity which is unnecessary and difficult to expect (css refs is otherwise invisible from userland), and, to policy implementations, this is an unnecessary restriction (e.g. blkcg wants to hold css refs for caching purposes but can't as that becomes visible as rmdir hang). Unfortunately, memcg currently depends on ->pre_destroy() retrials and cgroup removal vetoing and can't be immmediately switched to the new behavior. This patch introduces the new behavior of not waiting for css refs to drain and maintains the old behavior for subsystems which have __DEPRECATED_clear_css_refs set. Once, memcg is updated, we can drop the code paths for the old behavior as proposed in the following patch. Note that the following patch is incorrect in that dput work item is in cgroup and may lose some of dputs when multiples css's are released back-to-back, and __css_put() triggers check_for_release() when refcnt reaches 0 instead of 1; however, it shows what part can be removed. http://thread.gmane.org/gmane.linux.kernel.containers/22559/focus=75251 Note that, in not-too-distant future, cgroup core will start emitting warning messages for subsys which require the old behavior, so please get moving. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2012-04-01 23:09:56 +04:00
{
struct cgroup_subsys_state *css =
container_of(work, struct cgroup_subsys_state, destroy_work);
struct cgroup_subsys *ss = css->ss;
cgroup: RCU protect each cgroup_subsys_state release With the planned unified hierarchy, individual css's will be created and destroyed dynamically across the lifetime of a cgroup. To enable such usages, css destruction is being decoupled from cgroup destruction. Most of the destruction path has been decoupled but the actual free of css still depends on cgroup free path. When all css refs are drained, css_release() kicks off css_free_work_fn() which puts the cgroup. When the cgroup refcnt reaches zero, cgroup_diput() is invoked which in turn schedules RCU free of the cgroup. After a grace period, all css's are freed along with the cgroup itself. This patch moves the RCU grace period and css freeing from cgroup release path to css release path. css_release(), instead of kicking off css_free_work_fn() directly, schedules RCU callback css_free_rcu_fn() which in turn kicks off css_free_work_fn() after a RCU grace period. css_free_work_fn() is updated to free the css directly. The five-way punting - percpu ref kill confirmation, a work item, percpu ref release, RCU grace period, and again a work item - is quite hairy but the work items are there only to provide process context and the actual sequence is kill confirm -> release -> RCU free, which isn't simple but not too crazy. This removes cgroup_css() usage after offline_css() allowing clearing cgroup->subsys[] from offline_css(), which makes it consistent with online_css() and brings it closer to proper lifetime management for individual css's. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-08-14 04:22:51 +04:00
struct cgroup *cgrp = css->cgroup;
cgroup: make css->refcnt clearing on cgroup removal optional Currently, cgroup removal tries to drain all css references. If there are active css references, the removal logic waits and retries ->pre_detroy() until either all refs drop to zero or removal is cancelled. This semantics is unusual and adds non-trivial complexity to cgroup core and IMHO is fundamentally misguided in that it couples internal implementation details (references to internal data structure) with externally visible operation (rmdir). To userland, this is a behavior peculiarity which is unnecessary and difficult to expect (css refs is otherwise invisible from userland), and, to policy implementations, this is an unnecessary restriction (e.g. blkcg wants to hold css refs for caching purposes but can't as that becomes visible as rmdir hang). Unfortunately, memcg currently depends on ->pre_destroy() retrials and cgroup removal vetoing and can't be immmediately switched to the new behavior. This patch introduces the new behavior of not waiting for css refs to drain and maintains the old behavior for subsystems which have __DEPRECATED_clear_css_refs set. Once, memcg is updated, we can drop the code paths for the old behavior as proposed in the following patch. Note that the following patch is incorrect in that dput work item is in cgroup and may lose some of dputs when multiples css's are released back-to-back, and __css_put() triggers check_for_release() when refcnt reaches 0 instead of 1; however, it shows what part can be removed. http://thread.gmane.org/gmane.linux.kernel.containers/22559/focus=75251 Note that, in not-too-distant future, cgroup core will start emitting warning messages for subsys which require the old behavior, so please get moving. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2012-04-01 23:09:56 +04:00
percpu_ref_exit(&css->refcnt);
if (ss) {
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
/* css free path */
struct cgroup_subsys_state *parent = css->parent;
int id = css->id;
ss->css_free(css);
cgroup_idr_remove(&ss->css_idr, id);
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
cgroup_put(cgrp);
if (parent)
css_put(parent);
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
} else {
/* cgroup free path */
atomic_dec(&cgrp->root->nr_cgrps);
cgroup_pidlist_destroy_all(cgrp);
cancel_work_sync(&cgrp->release_agent_work);
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
if (cgroup_parent(cgrp)) {
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
/*
* We get a ref to the parent, and put the ref when
* this cgroup is being freed, so it's guaranteed
* that the parent won't be destroyed before its
* children.
*/
cgroup_put(cgroup_parent(cgrp));
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
kernfs_put(cgrp->kn);
kfree(cgrp);
} else {
/*
* This is root cgroup's refcnt reaching zero,
* which indicates that the root should be
* released.
*/
cgroup_destroy_root(cgrp->root);
}
}
cgroup: make css->refcnt clearing on cgroup removal optional Currently, cgroup removal tries to drain all css references. If there are active css references, the removal logic waits and retries ->pre_detroy() until either all refs drop to zero or removal is cancelled. This semantics is unusual and adds non-trivial complexity to cgroup core and IMHO is fundamentally misguided in that it couples internal implementation details (references to internal data structure) with externally visible operation (rmdir). To userland, this is a behavior peculiarity which is unnecessary and difficult to expect (css refs is otherwise invisible from userland), and, to policy implementations, this is an unnecessary restriction (e.g. blkcg wants to hold css refs for caching purposes but can't as that becomes visible as rmdir hang). Unfortunately, memcg currently depends on ->pre_destroy() retrials and cgroup removal vetoing and can't be immmediately switched to the new behavior. This patch introduces the new behavior of not waiting for css refs to drain and maintains the old behavior for subsystems which have __DEPRECATED_clear_css_refs set. Once, memcg is updated, we can drop the code paths for the old behavior as proposed in the following patch. Note that the following patch is incorrect in that dput work item is in cgroup and may lose some of dputs when multiples css's are released back-to-back, and __css_put() triggers check_for_release() when refcnt reaches 0 instead of 1; however, it shows what part can be removed. http://thread.gmane.org/gmane.linux.kernel.containers/22559/focus=75251 Note that, in not-too-distant future, cgroup core will start emitting warning messages for subsys which require the old behavior, so please get moving. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2012-04-01 23:09:56 +04:00
}
cgroup: RCU protect each cgroup_subsys_state release With the planned unified hierarchy, individual css's will be created and destroyed dynamically across the lifetime of a cgroup. To enable such usages, css destruction is being decoupled from cgroup destruction. Most of the destruction path has been decoupled but the actual free of css still depends on cgroup free path. When all css refs are drained, css_release() kicks off css_free_work_fn() which puts the cgroup. When the cgroup refcnt reaches zero, cgroup_diput() is invoked which in turn schedules RCU free of the cgroup. After a grace period, all css's are freed along with the cgroup itself. This patch moves the RCU grace period and css freeing from cgroup release path to css release path. css_release(), instead of kicking off css_free_work_fn() directly, schedules RCU callback css_free_rcu_fn() which in turn kicks off css_free_work_fn() after a RCU grace period. css_free_work_fn() is updated to free the css directly. The five-way punting - percpu ref kill confirmation, a work item, percpu ref release, RCU grace period, and again a work item - is quite hairy but the work items are there only to provide process context and the actual sequence is kill confirm -> release -> RCU free, which isn't simple but not too crazy. This removes cgroup_css() usage after offline_css() allowing clearing cgroup->subsys[] from offline_css(), which makes it consistent with online_css() and brings it closer to proper lifetime management for individual css's. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-08-14 04:22:51 +04:00
static void css_free_rcu_fn(struct rcu_head *rcu_head)
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
{
struct cgroup_subsys_state *css =
cgroup: RCU protect each cgroup_subsys_state release With the planned unified hierarchy, individual css's will be created and destroyed dynamically across the lifetime of a cgroup. To enable such usages, css destruction is being decoupled from cgroup destruction. Most of the destruction path has been decoupled but the actual free of css still depends on cgroup free path. When all css refs are drained, css_release() kicks off css_free_work_fn() which puts the cgroup. When the cgroup refcnt reaches zero, cgroup_diput() is invoked which in turn schedules RCU free of the cgroup. After a grace period, all css's are freed along with the cgroup itself. This patch moves the RCU grace period and css freeing from cgroup release path to css release path. css_release(), instead of kicking off css_free_work_fn() directly, schedules RCU callback css_free_rcu_fn() which in turn kicks off css_free_work_fn() after a RCU grace period. css_free_work_fn() is updated to free the css directly. The five-way punting - percpu ref kill confirmation, a work item, percpu ref release, RCU grace period, and again a work item - is quite hairy but the work items are there only to provide process context and the actual sequence is kill confirm -> release -> RCU free, which isn't simple but not too crazy. This removes cgroup_css() usage after offline_css() allowing clearing cgroup->subsys[] from offline_css(), which makes it consistent with online_css() and brings it closer to proper lifetime management for individual css's. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-08-14 04:22:51 +04:00
container_of(rcu_head, struct cgroup_subsys_state, rcu_head);
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
INIT_WORK(&css->destroy_work, css_free_work_fn);
cgroup: use a dedicated workqueue for cgroup destruction Since be44562613851 ("cgroup: remove synchronize_rcu() from cgroup_diput()"), cgroup destruction path makes use of workqueue. css freeing is performed from a work item from that point on and a later commit, ea15f8ccdb430 ("cgroup: split cgroup destruction into two steps"), moves css offlining to workqueue too. As cgroup destruction isn't depended upon for memory reclaim, the destruction work items were put on the system_wq; unfortunately, some controller may block in the destruction path for considerable duration while holding cgroup_mutex. As large part of destruction path is synchronized through cgroup_mutex, when combined with high rate of cgroup removals, this has potential to fill up system_wq's max_active of 256. Also, it turns out that memcg's css destruction path ends up queueing and waiting for work items on system_wq through work_on_cpu(). If such operation happens while system_wq is fully occupied by cgroup destruction work items, work_on_cpu() can't make forward progress because system_wq is full and other destruction work items on system_wq can't make forward progress because the work item waiting for work_on_cpu() is holding cgroup_mutex, leading to deadlock. This can be fixed by queueing destruction work items on a separate workqueue. This patch creates a dedicated workqueue - cgroup_destroy_wq - for this purpose. As these work items shouldn't have inter-dependencies and mostly serialized by cgroup_mutex anyway, giving high concurrency level doesn't buy anything and the workqueue's @max_active is set to 1 so that destruction work items are executed one by one on each CPU. Hugh Dickins: Because cgroup_init() is run before init_workqueues(), cgroup_destroy_wq can't be allocated from cgroup_init(). Do it from a separate core_initcall(). In the future, we probably want to reorder so that workqueue init happens before cgroup_init(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Hugh Dickins <hughd@google.com> Reported-by: Shawn Bohrer <shawn.bohrer@gmail.com> Link: http://lkml.kernel.org/r/20131111220626.GA7509@sbohrermbp13-local.rgmadvisors.com Link: http://lkml.kernel.org/g/alpine.LNX.2.00.1310301606080.2333@eggly.anvils Cc: stable@vger.kernel.org # v3.9+
2013-11-23 02:14:39 +04:00
queue_work(cgroup_destroy_wq, &css->destroy_work);
cgroup: make css->refcnt clearing on cgroup removal optional Currently, cgroup removal tries to drain all css references. If there are active css references, the removal logic waits and retries ->pre_detroy() until either all refs drop to zero or removal is cancelled. This semantics is unusual and adds non-trivial complexity to cgroup core and IMHO is fundamentally misguided in that it couples internal implementation details (references to internal data structure) with externally visible operation (rmdir). To userland, this is a behavior peculiarity which is unnecessary and difficult to expect (css refs is otherwise invisible from userland), and, to policy implementations, this is an unnecessary restriction (e.g. blkcg wants to hold css refs for caching purposes but can't as that becomes visible as rmdir hang). Unfortunately, memcg currently depends on ->pre_destroy() retrials and cgroup removal vetoing and can't be immmediately switched to the new behavior. This patch introduces the new behavior of not waiting for css refs to drain and maintains the old behavior for subsystems which have __DEPRECATED_clear_css_refs set. Once, memcg is updated, we can drop the code paths for the old behavior as proposed in the following patch. Note that the following patch is incorrect in that dput work item is in cgroup and may lose some of dputs when multiples css's are released back-to-back, and __css_put() triggers check_for_release() when refcnt reaches 0 instead of 1; however, it shows what part can be removed. http://thread.gmane.org/gmane.linux.kernel.containers/22559/focus=75251 Note that, in not-too-distant future, cgroup core will start emitting warning messages for subsys which require the old behavior, so please get moving. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2012-04-01 23:09:56 +04:00
}
static void css_release_work_fn(struct work_struct *work)
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
{
struct cgroup_subsys_state *css =
container_of(work, struct cgroup_subsys_state, destroy_work);
struct cgroup_subsys *ss = css->ss;
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
struct cgroup *cgrp = css->cgroup;
mutex_lock(&cgroup_mutex);
css->flags |= CSS_RELEASED;
list_del_rcu(&css->sibling);
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
if (ss) {
/* css release path */
cgroup_idr_replace(&ss->css_idr, NULL, css->id);
if (ss->css_released)
ss->css_released(css);
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
} else {
/* cgroup release path */
cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
cgrp->id = -1;
/*
* There are two control paths which try to determine
* cgroup from dentry without going through kernfs -
* cgroupstats_build() and css_tryget_online_from_dir().
* Those are supported by RCU protecting clearing of
* cgrp->kn->priv backpointer.
*/
if (cgrp->kn)
RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv,
NULL);
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
}
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
mutex_unlock(&cgroup_mutex);
cgroup: RCU protect each cgroup_subsys_state release With the planned unified hierarchy, individual css's will be created and destroyed dynamically across the lifetime of a cgroup. To enable such usages, css destruction is being decoupled from cgroup destruction. Most of the destruction path has been decoupled but the actual free of css still depends on cgroup free path. When all css refs are drained, css_release() kicks off css_free_work_fn() which puts the cgroup. When the cgroup refcnt reaches zero, cgroup_diput() is invoked which in turn schedules RCU free of the cgroup. After a grace period, all css's are freed along with the cgroup itself. This patch moves the RCU grace period and css freeing from cgroup release path to css release path. css_release(), instead of kicking off css_free_work_fn() directly, schedules RCU callback css_free_rcu_fn() which in turn kicks off css_free_work_fn() after a RCU grace period. css_free_work_fn() is updated to free the css directly. The five-way punting - percpu ref kill confirmation, a work item, percpu ref release, RCU grace period, and again a work item - is quite hairy but the work items are there only to provide process context and the actual sequence is kill confirm -> release -> RCU free, which isn't simple but not too crazy. This removes cgroup_css() usage after offline_css() allowing clearing cgroup->subsys[] from offline_css(), which makes it consistent with online_css() and brings it closer to proper lifetime management for individual css's. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-08-14 04:22:51 +04:00
call_rcu(&css->rcu_head, css_free_rcu_fn);
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
}
static void css_release(struct percpu_ref *ref)
{
struct cgroup_subsys_state *css =
container_of(ref, struct cgroup_subsys_state, refcnt);
INIT_WORK(&css->destroy_work, css_release_work_fn);
queue_work(cgroup_destroy_wq, &css->destroy_work);
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
}
static void init_and_link_css(struct cgroup_subsys_state *css,
struct cgroup_subsys *ss, struct cgroup *cgrp)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
lockdep_assert_held(&cgroup_mutex);
cgroup_get(cgrp);
memset(css, 0, sizeof(*css));
css->cgroup = cgrp;
css->ss = ss;
INIT_LIST_HEAD(&css->sibling);
INIT_LIST_HEAD(&css->children);
css->serial_nr = css_serial_nr_next++;
atomic_set(&css->online_cnt, 0);
if (cgroup_parent(cgrp)) {
css->parent = cgroup_css(cgroup_parent(cgrp), ss);
css_get(css->parent);
}
cgroup: make css->refcnt clearing on cgroup removal optional Currently, cgroup removal tries to drain all css references. If there are active css references, the removal logic waits and retries ->pre_detroy() until either all refs drop to zero or removal is cancelled. This semantics is unusual and adds non-trivial complexity to cgroup core and IMHO is fundamentally misguided in that it couples internal implementation details (references to internal data structure) with externally visible operation (rmdir). To userland, this is a behavior peculiarity which is unnecessary and difficult to expect (css refs is otherwise invisible from userland), and, to policy implementations, this is an unnecessary restriction (e.g. blkcg wants to hold css refs for caching purposes but can't as that becomes visible as rmdir hang). Unfortunately, memcg currently depends on ->pre_destroy() retrials and cgroup removal vetoing and can't be immmediately switched to the new behavior. This patch introduces the new behavior of not waiting for css refs to drain and maintains the old behavior for subsystems which have __DEPRECATED_clear_css_refs set. Once, memcg is updated, we can drop the code paths for the old behavior as proposed in the following patch. Note that the following patch is incorrect in that dput work item is in cgroup and may lose some of dputs when multiples css's are released back-to-back, and __css_put() triggers check_for_release() when refcnt reaches 0 instead of 1; however, it shows what part can be removed. http://thread.gmane.org/gmane.linux.kernel.containers/22559/focus=75251 Note that, in not-too-distant future, cgroup core will start emitting warning messages for subsys which require the old behavior, so please get moving. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2012-04-01 23:09:56 +04:00
BUG_ON(cgroup_css(cgrp, ss));
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
/* invoke ->css_online() on a new CSS and mark it online if successful */
static int online_css(struct cgroup_subsys_state *css)
{
struct cgroup_subsys *ss = css->ss;
int ret = 0;
lockdep_assert_held(&cgroup_mutex);
if (ss->css_online)
cgroup: pass around cgroup_subsys_state instead of cgroup in subsystem methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup * in subsystem implementations for the following reasons. * With unified hierarchy, subsystems will be dynamically bound and unbound from cgroups and thus css's (cgroup_subsys_state) may be created and destroyed dynamically over the lifetime of a cgroup, which is different from the current state where all css's are allocated and destroyed together with the associated cgroup. This in turn means that cgroup_css() should be synchronized and may return NULL, making it more cumbersome to use. * Differing levels of per-subsystem granularity in the unified hierarchy means that the task and descendant iterators should behave differently depending on the specific subsystem the iteration is being performed for. * In majority of the cases, subsystems only care about its part in the cgroup hierarchy - ie. the hierarchy of css's. Subsystem methods often obtain the matching css pointer from the cgroup and don't bother with the cgroup pointer itself. Passing around css fits much better. This patch converts all cgroup_subsys methods to take @css instead of @cgroup. The conversions are mostly straight-forward. A few noteworthy changes are * ->css_alloc() now takes css of the parent cgroup rather than the pointer to the new cgroup as the css for the new cgroup doesn't exist yet. Knowing the parent css is enough for all the existing subsystems. * In kernel/cgroup.c::offline_css(), unnecessary open coded css dereference is replaced with local variable access. This patch shouldn't cause any behavior differences. v2: Unnecessary explicit cgrp->subsys[] deref in css_online() replaced with local variable @css as suggested by Li Zefan. Rebased on top of new for-3.12 which includes for-3.11-fixes so that ->css_free() invocation added by da0a12caff ("cgroup: fix a leak when percpu_ref_init() fails") is converted too. Suggested by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:23 +04:00
ret = ss->css_online(css);
if (!ret) {
cgroup: pass around cgroup_subsys_state instead of cgroup in subsystem methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup * in subsystem implementations for the following reasons. * With unified hierarchy, subsystems will be dynamically bound and unbound from cgroups and thus css's (cgroup_subsys_state) may be created and destroyed dynamically over the lifetime of a cgroup, which is different from the current state where all css's are allocated and destroyed together with the associated cgroup. This in turn means that cgroup_css() should be synchronized and may return NULL, making it more cumbersome to use. * Differing levels of per-subsystem granularity in the unified hierarchy means that the task and descendant iterators should behave differently depending on the specific subsystem the iteration is being performed for. * In majority of the cases, subsystems only care about its part in the cgroup hierarchy - ie. the hierarchy of css's. Subsystem methods often obtain the matching css pointer from the cgroup and don't bother with the cgroup pointer itself. Passing around css fits much better. This patch converts all cgroup_subsys methods to take @css instead of @cgroup. The conversions are mostly straight-forward. A few noteworthy changes are * ->css_alloc() now takes css of the parent cgroup rather than the pointer to the new cgroup as the css for the new cgroup doesn't exist yet. Knowing the parent css is enough for all the existing subsystems. * In kernel/cgroup.c::offline_css(), unnecessary open coded css dereference is replaced with local variable access. This patch shouldn't cause any behavior differences. v2: Unnecessary explicit cgrp->subsys[] deref in css_online() replaced with local variable @css as suggested by Li Zefan. Rebased on top of new for-3.12 which includes for-3.11-fixes so that ->css_free() invocation added by da0a12caff ("cgroup: fix a leak when percpu_ref_init() fails") is converted too. Suggested by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:23 +04:00
css->flags |= CSS_ONLINE;
rcu_assign_pointer(css->cgroup->subsys[ss->id], css);
atomic_inc(&css->online_cnt);
if (css->parent)
atomic_inc(&css->parent->online_cnt);
}
return ret;
}
/* if the CSS is online, invoke ->css_offline() on it and mark it offline */
static void offline_css(struct cgroup_subsys_state *css)
{
struct cgroup_subsys *ss = css->ss;
lockdep_assert_held(&cgroup_mutex);
if (!(css->flags & CSS_ONLINE))
return;
if (ss->css_reset)
ss->css_reset(css);
if (ss->css_offline)
cgroup: pass around cgroup_subsys_state instead of cgroup in subsystem methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup * in subsystem implementations for the following reasons. * With unified hierarchy, subsystems will be dynamically bound and unbound from cgroups and thus css's (cgroup_subsys_state) may be created and destroyed dynamically over the lifetime of a cgroup, which is different from the current state where all css's are allocated and destroyed together with the associated cgroup. This in turn means that cgroup_css() should be synchronized and may return NULL, making it more cumbersome to use. * Differing levels of per-subsystem granularity in the unified hierarchy means that the task and descendant iterators should behave differently depending on the specific subsystem the iteration is being performed for. * In majority of the cases, subsystems only care about its part in the cgroup hierarchy - ie. the hierarchy of css's. Subsystem methods often obtain the matching css pointer from the cgroup and don't bother with the cgroup pointer itself. Passing around css fits much better. This patch converts all cgroup_subsys methods to take @css instead of @cgroup. The conversions are mostly straight-forward. A few noteworthy changes are * ->css_alloc() now takes css of the parent cgroup rather than the pointer to the new cgroup as the css for the new cgroup doesn't exist yet. Knowing the parent css is enough for all the existing subsystems. * In kernel/cgroup.c::offline_css(), unnecessary open coded css dereference is replaced with local variable access. This patch shouldn't cause any behavior differences. v2: Unnecessary explicit cgrp->subsys[] deref in css_online() replaced with local variable @css as suggested by Li Zefan. Rebased on top of new for-3.12 which includes for-3.11-fixes so that ->css_free() invocation added by da0a12caff ("cgroup: fix a leak when percpu_ref_init() fails") is converted too. Suggested by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:23 +04:00
ss->css_offline(css);
cgroup: pass around cgroup_subsys_state instead of cgroup in subsystem methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup * in subsystem implementations for the following reasons. * With unified hierarchy, subsystems will be dynamically bound and unbound from cgroups and thus css's (cgroup_subsys_state) may be created and destroyed dynamically over the lifetime of a cgroup, which is different from the current state where all css's are allocated and destroyed together with the associated cgroup. This in turn means that cgroup_css() should be synchronized and may return NULL, making it more cumbersome to use. * Differing levels of per-subsystem granularity in the unified hierarchy means that the task and descendant iterators should behave differently depending on the specific subsystem the iteration is being performed for. * In majority of the cases, subsystems only care about its part in the cgroup hierarchy - ie. the hierarchy of css's. Subsystem methods often obtain the matching css pointer from the cgroup and don't bother with the cgroup pointer itself. Passing around css fits much better. This patch converts all cgroup_subsys methods to take @css instead of @cgroup. The conversions are mostly straight-forward. A few noteworthy changes are * ->css_alloc() now takes css of the parent cgroup rather than the pointer to the new cgroup as the css for the new cgroup doesn't exist yet. Knowing the parent css is enough for all the existing subsystems. * In kernel/cgroup.c::offline_css(), unnecessary open coded css dereference is replaced with local variable access. This patch shouldn't cause any behavior differences. v2: Unnecessary explicit cgrp->subsys[] deref in css_online() replaced with local variable @css as suggested by Li Zefan. Rebased on top of new for-3.12 which includes for-3.11-fixes so that ->css_free() invocation added by da0a12caff ("cgroup: fix a leak when percpu_ref_init() fails") is converted too. Suggested by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:23 +04:00
css->flags &= ~CSS_ONLINE;
RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL);
cgroup: implement dynamic subtree controller enable/disable on the default hierarchy cgroup is switching away from multiple hierarchies and will use one unified default hierarchy where controllers can be dynamically enabled and disabled per subtree. The default hierarchy will serve as the unified hierarchy to which all controllers are attached and a css on the default hierarchy would need to also serve the tasks of descendant cgroups which don't have the controller enabled - ie. the tree may be collapsed from leaf towards root when viewed from specific controllers. This has been implemented through effective css in the previous patches. This patch finally implements dynamic subtree controller enable/disable on the default hierarchy via a new knob - "cgroup.subtree_control" which controls which controllers are enabled on the child cgroups. Let's assume a hierarchy like the following. root - A - B - C \ D root's "cgroup.subtree_control" determines which controllers are enabled on A. A's on B. B's on C and D. This coincides with the fact that controllers on the immediate sub-level are used to distribute the resources of the parent. In fact, it's natural to assume that resource control knobs of a child belong to its parent. Enabling a controller in "cgroup.subtree_control" declares that distribution of the respective resources of the cgroup will be controlled. Note that this means that controller enable states are shared among siblings. The default hierarchy has an extra restriction - only cgroups which don't contain any task may have controllers enabled in "cgroup.subtree_control". Combined with the other properties of the default hierarchy, this guarantees that, from the view point of controllers, tasks are only on the leaf cgroups. In other words, only leaf csses may contain tasks. This rules out situations where child cgroups compete against internal tasks of the parent, which is a competition between two different types of entities without any clear way to determine resource distribution between the two. Different controllers handle it differently and all the implemented behaviors are ambiguous, ad-hoc, cumbersome and/or just wrong. Having this structural constraints imposed from cgroup core removes the burden from controller implementations and enables showing one consistent behavior across all controllers. When a controller is enabled or disabled, css associations for the controller in the subtrees of each child should be updated. After enabling, the whole subtree of a child should point to the new css of the child. After disabling, the whole subtree of a child should point to the cgroup's css. This is implemented by first updating cgroup states such that cgroup_e_css() result points to the appropriate css and then invoking cgroup_update_dfl_csses() which migrates all tasks in the affected subtrees to the self cgroup on the default hierarchy. * When read, "cgroup.subtree_control" lists all the currently enabled controllers on the children of the cgroup. * White-space separated list of controller names prefixed with either '+' or '-' can be written to "cgroup.subtree_control". The ones prefixed with '+' are enabled on the controller and '-' disabled. * A controller can be enabled iff the parent's "cgroup.subtree_control" enables it and disabled iff no child's "cgroup.subtree_control" has it enabled. * If a cgroup has tasks, no controller can be enabled via "cgroup.subtree_control". Likewise, if "cgroup.subtree_control" has some controllers enabled, tasks can't be migrated into the cgroup. * All controllers which aren't bound on other hierarchies are automatically associated with the root cgroup of the default hierarchy. All the controllers which are bound to the default hierarchy are listed in the read-only file "cgroup.controllers" in the root directory. * "cgroup.controllers" in all non-root cgroups is read-only file whose content is equal to that of "cgroup.subtree_control" of the parent. This indicates which controllers can be used in the cgroup's "cgroup.subtree_control". This is still experimental and there are some holes, one of which is that ->can_attach() failure during cgroup_update_dfl_csses() may leave the cgroups in an undefined state. The issues will be addressed by future patches. v2: Non-root cgroups now also have "cgroup.controllers". Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-04-23 19:13:16 +04:00
wake_up_all(&css->cgroup->offline_waitq);
}
/**
* css_create - create a cgroup_subsys_state
* @cgrp: the cgroup new css will be associated with
* @ss: the subsys of new css
*
* Create a new css associated with @cgrp - @ss pair. On success, the new
* css is online and installed in @cgrp. This function doesn't create the
* interface files. Returns 0 on success, -errno on failure.
*/
static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
struct cgroup_subsys *ss)
{
struct cgroup *parent = cgroup_parent(cgrp);
struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss);
struct cgroup_subsys_state *css;
int err;
lockdep_assert_held(&cgroup_mutex);
css = ss->css_alloc(parent_css);
if (IS_ERR(css))
return css;
init_and_link_css(css, ss, cgrp);
err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL);
if (err)
goto err_free_css;
err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL);
if (err < 0)
goto err_free_percpu_ref;
css->id = err;
/* @css is ready to be brought online now, make it visible */
list_add_tail_rcu(&css->sibling, &parent_css->children);
cgroup_idr_replace(&ss->css_idr, css, css->id);
err = online_css(css);
if (err)
goto err_list_del;
if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
cgroup_parent(parent)) {
pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
current->comm, current->pid, ss->name);
if (!strcmp(ss->name, "memory"))
pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n");
ss->warned_broken_hierarchy = true;
}
return css;
err_list_del:
list_del_rcu(&css->sibling);
cgroup_idr_remove(&ss->css_idr, css->id);
err_free_percpu_ref:
percpu_ref_exit(&css->refcnt);
err_free_css:
call_rcu(&css->rcu_head, css_free_rcu_fn);
return ERR_PTR(err);
}
static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
umode_t mode)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
struct cgroup *parent, *cgrp, *tcgrp;
struct cgroup_root *root;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
struct cgroup_subsys *ss;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct kernfs_node *kn;
int level, ssid, ret;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* Do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable.
*/
if (strchr(name, '\n'))
return -EINVAL;
parent = cgroup_kn_lock_live(parent_kn);
if (!parent)
return -ENODEV;
root = parent->root;
level = parent->level + 1;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* allocate the cgroup and its ID, 0 is reserved for the root */
cgrp = kzalloc(sizeof(*cgrp) +
sizeof(cgrp->ancestor_ids[0]) * (level + 1), GFP_KERNEL);
if (!cgrp) {
ret = -ENOMEM;
goto out_unlock;
cgroup: protect modifications to cgroup_idr with cgroup_mutex Setup cgroupfs like this: # mount -t cgroup -o cpuacct xxx /cgroup # mkdir /cgroup/sub1 # mkdir /cgroup/sub2 Then run these two commands: # for ((; ;)) { mkdir /cgroup/sub1/tmp && rmdir /mnt/sub1/tmp; } & # for ((; ;)) { mkdir /cgroup/sub2/tmp && rmdir /mnt/sub2/tmp; } & After seconds you may see this warning: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 25243 at lib/idr.c:527 sub_remove+0x87/0x1b0() idr_remove called for id=6 which is not allocated. ... Call Trace: [<ffffffff8156063c>] dump_stack+0x7a/0x96 [<ffffffff810591ac>] warn_slowpath_common+0x8c/0xc0 [<ffffffff81059296>] warn_slowpath_fmt+0x46/0x50 [<ffffffff81300aa7>] sub_remove+0x87/0x1b0 [<ffffffff810f3f02>] ? css_killed_work_fn+0x32/0x1b0 [<ffffffff81300bf5>] idr_remove+0x25/0xd0 [<ffffffff810f2bab>] cgroup_destroy_css_killed+0x5b/0xc0 [<ffffffff810f4000>] css_killed_work_fn+0x130/0x1b0 [<ffffffff8107cdbc>] process_one_work+0x26c/0x550 [<ffffffff8107eefe>] worker_thread+0x12e/0x3b0 [<ffffffff81085f96>] kthread+0xe6/0xf0 [<ffffffff81570bac>] ret_from_fork+0x7c/0xb0 ---[ end trace 2d1577ec10cf80d0 ]--- It's because allocating/removing cgroup ID is not properly synchronized. The bug was introduced when we converted cgroup_ida to cgroup_idr. While synchronization is already done inside ida_simple_{get,remove}(), users are responsible for concurrent calls to idr_{alloc,remove}(). tj: Refreshed on top of b58c89986a77 ("cgroup: fix error return from cgroup_create()"). Fixes: 4e96ee8e981b ("cgroup: convert cgroup_ida to cgroup_idr") Cc: <stable@vger.kernel.org> #3.12+ Reported-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2014-02-11 12:05:46 +04:00
}
ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL);
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
if (ret)
goto out_free_cgrp;
cgroup: protect modifications to cgroup_idr with cgroup_mutex Setup cgroupfs like this: # mount -t cgroup -o cpuacct xxx /cgroup # mkdir /cgroup/sub1 # mkdir /cgroup/sub2 Then run these two commands: # for ((; ;)) { mkdir /cgroup/sub1/tmp && rmdir /mnt/sub1/tmp; } & # for ((; ;)) { mkdir /cgroup/sub2/tmp && rmdir /mnt/sub2/tmp; } & After seconds you may see this warning: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 25243 at lib/idr.c:527 sub_remove+0x87/0x1b0() idr_remove called for id=6 which is not allocated. ... Call Trace: [<ffffffff8156063c>] dump_stack+0x7a/0x96 [<ffffffff810591ac>] warn_slowpath_common+0x8c/0xc0 [<ffffffff81059296>] warn_slowpath_fmt+0x46/0x50 [<ffffffff81300aa7>] sub_remove+0x87/0x1b0 [<ffffffff810f3f02>] ? css_killed_work_fn+0x32/0x1b0 [<ffffffff81300bf5>] idr_remove+0x25/0xd0 [<ffffffff810f2bab>] cgroup_destroy_css_killed+0x5b/0xc0 [<ffffffff810f4000>] css_killed_work_fn+0x130/0x1b0 [<ffffffff8107cdbc>] process_one_work+0x26c/0x550 [<ffffffff8107eefe>] worker_thread+0x12e/0x3b0 [<ffffffff81085f96>] kthread+0xe6/0xf0 [<ffffffff81570bac>] ret_from_fork+0x7c/0xb0 ---[ end trace 2d1577ec10cf80d0 ]--- It's because allocating/removing cgroup ID is not properly synchronized. The bug was introduced when we converted cgroup_ida to cgroup_idr. While synchronization is already done inside ida_simple_{get,remove}(), users are responsible for concurrent calls to idr_{alloc,remove}(). tj: Refreshed on top of b58c89986a77 ("cgroup: fix error return from cgroup_create()"). Fixes: 4e96ee8e981b ("cgroup: convert cgroup_ida to cgroup_idr") Cc: <stable@vger.kernel.org> #3.12+ Reported-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2014-02-11 12:05:46 +04:00
/*
* Temporarily set the pointer to NULL, so idr_find() won't return
* a half-baked cgroup.
*/
cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL);
cgroup: protect modifications to cgroup_idr with cgroup_mutex Setup cgroupfs like this: # mount -t cgroup -o cpuacct xxx /cgroup # mkdir /cgroup/sub1 # mkdir /cgroup/sub2 Then run these two commands: # for ((; ;)) { mkdir /cgroup/sub1/tmp && rmdir /mnt/sub1/tmp; } & # for ((; ;)) { mkdir /cgroup/sub2/tmp && rmdir /mnt/sub2/tmp; } & After seconds you may see this warning: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 25243 at lib/idr.c:527 sub_remove+0x87/0x1b0() idr_remove called for id=6 which is not allocated. ... Call Trace: [<ffffffff8156063c>] dump_stack+0x7a/0x96 [<ffffffff810591ac>] warn_slowpath_common+0x8c/0xc0 [<ffffffff81059296>] warn_slowpath_fmt+0x46/0x50 [<ffffffff81300aa7>] sub_remove+0x87/0x1b0 [<ffffffff810f3f02>] ? css_killed_work_fn+0x32/0x1b0 [<ffffffff81300bf5>] idr_remove+0x25/0xd0 [<ffffffff810f2bab>] cgroup_destroy_css_killed+0x5b/0xc0 [<ffffffff810f4000>] css_killed_work_fn+0x130/0x1b0 [<ffffffff8107cdbc>] process_one_work+0x26c/0x550 [<ffffffff8107eefe>] worker_thread+0x12e/0x3b0 [<ffffffff81085f96>] kthread+0xe6/0xf0 [<ffffffff81570bac>] ret_from_fork+0x7c/0xb0 ---[ end trace 2d1577ec10cf80d0 ]--- It's because allocating/removing cgroup ID is not properly synchronized. The bug was introduced when we converted cgroup_ida to cgroup_idr. While synchronization is already done inside ida_simple_{get,remove}(), users are responsible for concurrent calls to idr_{alloc,remove}(). tj: Refreshed on top of b58c89986a77 ("cgroup: fix error return from cgroup_create()"). Fixes: 4e96ee8e981b ("cgroup: convert cgroup_ida to cgroup_idr") Cc: <stable@vger.kernel.org> #3.12+ Reported-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2014-02-11 12:05:46 +04:00
if (cgrp->id < 0) {
ret = -ENOMEM;
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
goto out_cancel_ref;
}
init_cgroup_housekeeping(cgrp);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
cgrp->self.parent = &parent->self;
cgrp->root = root;
cgrp->level = level;
for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp))
cgrp->ancestor_ids[tcgrp->level] = tcgrp->id;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
if (notify_on_release(parent))
set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags))
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
cgroup: add clone_children control file The ns_cgroup is a control group interacting with the namespaces. When a new namespace is created, a corresponding cgroup is automatically created too. The cgroup name is the pid of the process who did 'unshare' or the child of 'clone'. This cgroup is tied with the namespace because it prevents a process to escape the control group and use the post_clone callback, so the child cgroup inherits the values of the parent cgroup. Unfortunately, the more we use this cgroup and the more we are facing problems with it: (1) when a process unshares, the cgroup name may conflict with a previous cgroup with the same pid, so unshare or clone return -EEXIST (2) the cgroup creation is out of control because there may have an application creating several namespaces where the system will automatically create several cgroups in his back and let them on the cgroupfs (eg. a vrf based on the network namespace). (3) the mix of (1) and (2) force an administrator to regularly check and clean these cgroups. This patchset removes the ns_cgroup by adding a new flag to the cgroup and the cgroupfs mount option. It enables the copy of the parent cgroup when a child cgroup is created. We can then safely remove the ns_cgroup as this flag brings a compatibility. We have now to manually create and add the task to a cgroup, which is consistent with the cgroup framework. This patch: Sent as an answer to a previous thread around the ns_cgroup. https://lists.linux-foundation.org/pipermail/containers/2009-June/018627.html It adds a control file 'clone_children' for a cgroup. This control file is a boolean specifying if the child cgroup should be a clone of the parent cgroup or not. The default value is 'false'. This flag makes the child cgroup to call the post_clone callback of all the subsystem, if it is available. At present, the cpuset is the only one which had implemented the post_clone callback. The option can be set at mount time by specifying the 'clone_children' mount option. Signed-off-by: Daniel Lezcano <daniel.lezcano@free.fr> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Acked-by: Paul Menage <menage@google.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Jamal Hadi Salim <hadi@cyberus.ca> Cc: Matt Helsley <matthltc@us.ibm.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-28 02:33:35 +04:00
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
/* create the directory */
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
if (IS_ERR(kn)) {
ret = PTR_ERR(kn);
goto out_free_id;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
}
cgrp->kn = kn;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/*
* This extra ref will be put in cgroup_free_fn() and guarantees
* that @cgrp->kn is always accessible.
*/
kernfs_get(kn);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
cgrp->self.serial_nr = css_serial_nr_next++;
cgroup: add cgroup->serial_nr and implement cgroup_next_sibling() Currently, there's no easy way to find out the next sibling cgroup unless it's known that the current cgroup is accessed from the parent's children list in a single RCU critical section. This in turn forces all iterators to require whole iteration to be enclosed in a single RCU critical section, which sometimes is too restrictive. This patch implements cgroup_next_sibling() which can reliably determine the next sibling regardless of the state of the current cgroup as long as it's accessible. It currently is impossible to determine the next sibling after dropping RCU read lock because the cgroup being iterated could be removed anytime and if RCU read lock is dropped, nothing guarantess its ->sibling.next pointer is accessible. A removed cgroup would continue to point to its next sibling for RCU accesses but stop receiving updates from the sibling. IOW, the next sibling could be removed and then complete its grace period while RCU read lock is dropped, making it unsafe to dereference ->sibling.next after dropping and re-acquiring RCU read lock. This can be solved by adding a way to traverse to the next sibling without dereferencing ->sibling.next. This patch adds a monotonically increasing cgroup serial number, cgroup->serial_nr, which guarantees that all cgroup->children lists are kept in increasing serial_nr order. A new function, cgroup_next_sibling(), is implemented, which, if CGRP_REMOVED is not set on the current cgroup, follows ->sibling.next; otherwise, traverses the parent's ->children list until it sees a sibling with higher ->serial_nr. This allows the function to always return the next sibling regardless of the state of the current cgroup without adding overhead in the fast path. Further patches will update the iterators to use cgroup_next_sibling() so that they allow dropping RCU read lock and blocking while iteration is in progress which in turn will be used to simplify controllers. v2: Typo fix as per Serge. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
2013-05-24 05:55:38 +04:00
/* allocation complete, commit to creation */
list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children);
atomic_inc(&root->nr_cgrps);
cgroup_get(parent);
/*
* @cgrp is now fully operational. If something fails after this
* point, it'll be released via the normal destruction path.
*/
cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id);
ret = cgroup_kn_set_ugid(kn);
if (ret)
goto out_destroy;
ret = css_populate_dir(&cgrp->self, NULL);
if (ret)
goto out_destroy;
/* let's create and online css's */
do_each_subsys_mask(ss, ssid, parent->subtree_ss_mask) {
struct cgroup_subsys_state *css;
css = css_create(cgrp, ss);
if (IS_ERR(css)) {
ret = PTR_ERR(css);
goto out_destroy;
}
if (parent->subtree_control & (1 << ssid)) {
ret = css_populate_dir(css, NULL);
if (ret)
goto out_destroy;
}
} while_each_subsys_mask();
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/*
* On the default hierarchy, a child doesn't automatically inherit
* subtree_control from the parent. Each is configured manually.
*/
if (!cgroup_on_dfl(cgrp)) {
cgrp->subtree_control = parent->subtree_control;
cgroup_refresh_subtree_ss_mask(cgrp);
}
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
kernfs_activate(kn);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
ret = 0;
goto out_unlock;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
out_free_id:
cgroup_idr_remove(&root->cgroup_idr, cgrp->id);
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
out_cancel_ref:
percpu_ref_exit(&cgrp->self.refcnt);
out_free_cgrp:
kfree(cgrp);
out_unlock:
cgroup_kn_unlock(parent_kn);
return ret;
out_destroy:
cgroup_destroy_locked(cgrp);
goto out_unlock;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
/*
* This is called when the refcnt of a css is confirmed to be killed.
* css_tryget_online() is now guaranteed to fail. Tell the subsystem to
* initate destruction and put the css ref from kill_css().
*/
static void css_killed_work_fn(struct work_struct *work)
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
{
struct cgroup_subsys_state *css =
container_of(work, struct cgroup_subsys_state, destroy_work);
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
mutex_lock(&cgroup_mutex);
do {
offline_css(css);
css_put(css);
/* @css can't go away while we're holding cgroup_mutex */
css = css->parent;
} while (css && atomic_dec_and_test(&css->online_cnt));
mutex_unlock(&cgroup_mutex);
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
}
/* css kill confirmation processing requires process context, bounce */
static void css_killed_ref_fn(struct percpu_ref *ref)
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
{
struct cgroup_subsys_state *css =
container_of(ref, struct cgroup_subsys_state, refcnt);
if (atomic_dec_and_test(&css->online_cnt)) {
INIT_WORK(&css->destroy_work, css_killed_work_fn);
queue_work(cgroup_destroy_wq, &css->destroy_work);
}
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
}
/**
* kill_css - destroy a css
* @css: css to destroy
*
* This function initiates destruction of @css by removing cgroup interface
* files and putting its base reference. ->css_offline() will be invoked
* asynchronously once css_tryget_online() is guaranteed to fail and when
* the reference count reaches zero, @css will be released.
*/
static void kill_css(struct cgroup_subsys_state *css)
{
lockdep_assert_held(&cgroup_mutex);
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
/*
* This must happen before css is disassociated with its cgroup.
* See seq_css() for details.
*/
css_clear_dir(css, NULL);
/*
* Killing would put the base ref, but we need to keep it alive
* until after ->css_offline().
*/
css_get(css);
/*
* cgroup core guarantees that, by the time ->css_offline() is
* invoked, no new css reference will be given out via
* css_tryget_online(). We can't simply call percpu_ref_kill() and
* proceed to offlining css's because percpu_ref_kill() doesn't
* guarantee that the ref is seen as killed on all CPUs on return.
*
* Use percpu_ref_kill_and_confirm() to get notifications as each
* css is confirmed to be seen as killed on all CPUs.
*/
percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
}
/**
* cgroup_destroy_locked - the first stage of cgroup destruction
* @cgrp: cgroup to be destroyed
*
* css's make use of percpu refcnts whose killing latency shouldn't be
* exposed to userland and are RCU protected. Also, cgroup core needs to
* guarantee that css_tryget_online() won't succeed by the time
* ->css_offline() is invoked. To satisfy all the requirements,
* destruction is implemented in the following two steps.
cgroup: use percpu refcnt for cgroup_subsys_states A css (cgroup_subsys_state) is how each cgroup is represented to a controller. As such, it can be used in hot paths across the various subsystems different controllers are associated with. One of the common operations is reference counting, which up until now has been implemented using a global atomic counter and can have significant adverse impact on scalability. For example, css refcnt can be gotten and put multiple times by blkcg for each IO request. For highops configurations which try to do as much per-cpu as possible, the global frequent refcnting can be very expensive. In general, given the various and hugely diverse paths css's end up being used from, we need to make it cheap and highly scalable. In its usage, css refcnting isn't very different from module refcnting. This patch converts css refcnting to use the recently added percpu_ref. css_get/tryget/put() directly maps to the matching percpu_ref operations and the deactivation logic is no longer necessary as percpu_ref already has refcnt killing. The only complication is that as the refcnt is per-cpu, percpu_ref_kill() in itself doesn't ensure that further tryget operations will fail, which we need to guarantee before invoking ->css_offline()'s. This is resolved collecting kill confirmation using percpu_ref_kill_and_confirm() and initiating the offline phase of destruction after all css refcnt's are confirmed to be seen as killed on all CPUs. The previous patches already splitted destruction into two phases, so percpu_ref_kill_and_confirm() can be hooked up easily. This patch removes css_refcnt() which is used for rcu dereference sanity check in css_id(). While we can add a percpu refcnt API to ask the same question, css_id() itself is scheduled to be removed fairly soon, so let's not bother with it. Just drop the sanity check and use rcu_dereference_raw() instead. v2: - init_cgroup_css() was calling percpu_ref_init() without checking the return value. This causes two problems - the obvious lack of error handling and percpu_ref_init() being called from cgroup_init_subsys() before the allocators are up, which triggers warnings but doesn't cause actual problems as the refcnt isn't used for roots anyway. Fix both by moving percpu_ref_init() to cgroup_create(). - The base references were put too early by percpu_ref_kill_and_confirm() and cgroup_offline_fn() put the refs one extra time. This wasn't noticeable because css's go through another RCU grace period before being freed. Update cgroup_destroy_locked() to grab an extra reference before killing the refcnts. This problem was noticed by Kent. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <koverstreet@google.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: "Alasdair G. Kergon" <agk@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Glauber Costa <glommer@gmail.com>
2013-06-14 06:39:16 +04:00
*
* s1. Verify @cgrp can be destroyed and mark it dying. Remove all
* userland visible parts and start killing the percpu refcnts of
* css's. Set up so that the next stage will be kicked off once all
* the percpu refcnts are confirmed to be killed.
*
* s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
* rest of destruction. Once all cgroup references are gone, the
* cgroup is RCU-freed.
*
* This function implements s1. After this step, @cgrp is gone as far as
* the userland is concerned and a new cgroup with the same name may be
* created. As cgroup doesn't care about the names internally, this
* doesn't cause any problem.
*/
static int cgroup_destroy_locked(struct cgroup *cgrp)
__releases(&cgroup_mutex) __acquires(&cgroup_mutex)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct cgroup_subsys_state *css;
int ssid;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
lockdep_assert_held(&cgroup_mutex);
/*
* Only migration can raise populated from zero and we're already
* holding cgroup_mutex.
*/
if (cgroup_is_populated(cgrp))
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
return -EBUSY;
/*
* Make sure there's no live children. We can't test emptiness of
* ->self.children as dead children linger on it while being
* drained; otherwise, "rmdir parent/child parent" may fail.
*/
if (css_has_online_children(&cgrp->self))
return -EBUSY;
/*
* Mark @cgrp dead. This prevents further task migration and child
* creation by disabling cgroup_lock_live_group().
*/
cgrp->self.flags &= ~CSS_ONLINE;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* initiate massacre of all css's */
for_each_css(css, ssid, cgrp)
kill_css(css);
/*
* Remove @cgrp directory along with the base files. @cgrp has an
* extra ref on its kn.
*/
kernfs_remove(cgrp->kn);
check_for_release(cgroup_parent(cgrp));
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
/* put the base reference */
cgroup: use cgroup->self.refcnt for cgroup refcnting Currently cgroup implements refcnting separately using atomic_t cgroup->refcnt. The destruction paths of cgroup and css are rather complex and bear a lot of similiarities including the use of RCU and bouncing to a work item. This patch makes cgroup use the refcnt of self css for refcnting instead of using its own. This makes cgroup refcnting use css's percpu refcnt and share the destruction mechanism. * css_release_work_fn() and css_free_work_fn() are updated to handle both csses and cgroups. This is a bit messy but should do until we can make cgroup->self a full css, which currently can't be done thanks to multiple hierarchies. * cgroup_destroy_locked() now performs percpu_ref_kill(&cgrp->self.refcnt) instead of cgroup_put(cgrp). * Negative refcnt sanity check in cgroup_get() is no longer necessary as percpu_ref already handles it. * Similarly, as a cgroup which hasn't been killed will never be released regardless of its refcnt value and percpu_ref has sanity check on kill, cgroup_is_dead() sanity check in cgroup_put() is no longer necessary. * As whether a refcnt reached zero or not can only be decided after the reference count is killed, cgroup_root->cgrp's refcnting can no longer be used to decide whether to kill the root or not. Let's make cgroup_kill_sb() explicitly initiate destruction if the root doesn't have any children. This makes sense anyway as unmounted cgroup hierarchy without any children should be destroyed. While this is a bit messy, this will allow pushing more bookkeeping towards cgroup->self and thus handling cgroups and csses in more uniform way. In the very long term, it should be possible to introduce a base subsystem and convert the self css to a proper one making things whole lot simpler and unified. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-05-14 17:15:02 +04:00
percpu_ref_kill(&cgrp->self.refcnt);
return 0;
};
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
static int cgroup_rmdir(struct kernfs_node *kn)
{
struct cgroup *cgrp;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
int ret = 0;
cgrp = cgroup_kn_lock_live(kn);
if (!cgrp)
return 0;
ret = cgroup_destroy_locked(cgrp);
cgroup_kn_unlock(kn);
return ret;
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
}
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
.remount_fs = cgroup_remount,
.show_options = cgroup_show_options,
.mkdir = cgroup_mkdir,
.rmdir = cgroup_rmdir,
.rename = cgroup_rename,
};
static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
{
struct cgroup_subsys_state *css;
pr_debug("Initializing cgroup subsys %s\n", ss->name);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
mutex_lock(&cgroup_mutex);
idr_init(&ss->css_idr);
INIT_LIST_HEAD(&ss->cfts);
cgroup: implement cgroup_add_cftypes() and friends Currently, cgroup directories are populated by subsys->populate() callback explicitly creating files on each cgroup creation. This level of flexibility isn't needed or desirable. It provides largely unused flexibility which call for abuses while severely limiting what the core layer can do through the lack of structure and conventions. Per each cgroup file type, the only distinction that cgroup users is making is whether a cgroup is root or not, which can easily be expressed with flags. This patch introduces cgroup_add_cftypes(). These deal with cftypes instead of individual files - controllers indicate that certain types of files exist for certain subsystem. Newly added CFTYPE_*_ON_ROOT flags indicate whether a cftype should be excluded or created only on the root cgroup. cgroup_add_cftypes() can be called any time whether the target subsystem is currently attached or not. cgroup core will create files on the existing cgroups as necessary. Also, cgroup_subsys->base_cftypes is added to ease registration of the base files for the subsystem. If non-NULL on subsys init, the cftypes pointed to by ->base_cftypes are automatically registered on subsys init / load. Further patches will convert the existing users and remove the file based interface. Note that this interface allows dynamic addition of files to an active controller. This will be used for sub-controller modularity and unified hierarchy in the longer term. This patch implements the new mechanism but doesn't apply it to any user. v2: replaced DECLARE_CGROUP_CFTYPES[_COND]() with cgroup_subsys->base_cftypes, which works better for cgroup_subsys which is loaded as module. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizf@cn.fujitsu.com>
2012-04-01 23:09:55 +04:00
/* Create the root cgroup state for this subsystem */
ss->root = &cgrp_dfl_root;
css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss));
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* We don't handle early failures gracefully */
BUG_ON(IS_ERR(css));
init_and_link_css(css, ss, &cgrp_dfl_root.cgrp);
/*
* Root csses are never destroyed and we can't initialize
* percpu_ref during early init. Disable refcnting.
*/
css->flags |= CSS_NO_REF;
if (early) {
/* allocation can't be done safely during early init */
css->id = 1;
} else {
css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL);
BUG_ON(css->id < 0);
}
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* Update the init_css_set to contain a subsys
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
* pointer to this state - since the subsystem is
* newly registered, all tasks and hence the
* init_css_set is in the subsystem's root cgroup. */
init_css_set.subsys[ss->id] = css;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
have_fork_callback |= (bool)ss->fork << ss->id;
have_exit_callback |= (bool)ss->exit << ss->id;
have_free_callback |= (bool)ss->free << ss->id;
have_canfork_callback |= (bool)ss->can_fork << ss->id;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/* At system boot, before all subsystems have been
* registered, no tasks have been forked, so we don't
* need to invoke fork callbacks here. */
BUG_ON(!list_empty(&init_task.tasks));
BUG_ON(online_css(css));
mutex_unlock(&cgroup_mutex);
}
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/**
* cgroup_init_early - cgroup initialization at system boot
*
* Initialize cgroups at system boot, and initialize any
* subsystems that request early init.
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
*/
int __init cgroup_init_early(void)
{
static struct cgroup_sb_opts __initdata opts;
struct cgroup_subsys *ss;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
int i;
init_cgroup_root(&cgrp_dfl_root, &opts);
cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF;
RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
for_each_subsys(ss, i) {
WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id,
"invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p id:name=%d:%s\n",
cgroup: clean up cgroup_subsys names and initialization cgroup_subsys is a bit messier than it needs to be. * The name of a subsys can be different from its internal identifier defined in cgroup_subsys.h. Most subsystems use the matching name but three - cpu, memory and perf_event - use different ones. * cgroup_subsys_id enums are postfixed with _subsys_id and each cgroup_subsys is postfixed with _subsys. cgroup.h is widely included throughout various subsystems, it doesn't and shouldn't have claim on such generic names which don't have any qualifier indicating that they belong to cgroup. * cgroup_subsys->subsys_id should always equal the matching cgroup_subsys_id enum; however, we require each controller to initialize it and then BUG if they don't match, which is a bit silly. This patch cleans up cgroup_subsys names and initialization by doing the followings. * cgroup_subsys_id enums are now postfixed with _cgrp_id, and each cgroup_subsys with _cgrp_subsys. * With the above, renaming subsys identifiers to match the userland visible names doesn't cause any naming conflicts. All non-matching identifiers are renamed to match the official names. cpu_cgroup -> cpu mem_cgroup -> memory perf -> perf_event * controllers no longer need to initialize ->subsys_id and ->name. They're generated in cgroup core and set automatically during boot. * Redundant cgroup_subsys declarations removed. * While updating BUG_ON()s in cgroup_init_early(), convert them to WARN()s. BUGging that early during boot is stupid - the kernel can't print anything, even through serial console and the trap handler doesn't even link stack frame properly for back-tracing. This patch doesn't introduce any behavior changes. v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs classid handling into core"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: "David S. Miller" <davem@davemloft.net> Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Ingo Molnar <mingo@redhat.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Thomas Graf <tgraf@suug.ch>
2014-02-08 19:36:58 +04:00
i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free,
ss->id, ss->name);
cgroup: clean up cgroup_subsys names and initialization cgroup_subsys is a bit messier than it needs to be. * The name of a subsys can be different from its internal identifier defined in cgroup_subsys.h. Most subsystems use the matching name but three - cpu, memory and perf_event - use different ones. * cgroup_subsys_id enums are postfixed with _subsys_id and each cgroup_subsys is postfixed with _subsys. cgroup.h is widely included throughout various subsystems, it doesn't and shouldn't have claim on such generic names which don't have any qualifier indicating that they belong to cgroup. * cgroup_subsys->subsys_id should always equal the matching cgroup_subsys_id enum; however, we require each controller to initialize it and then BUG if they don't match, which is a bit silly. This patch cleans up cgroup_subsys names and initialization by doing the followings. * cgroup_subsys_id enums are now postfixed with _cgrp_id, and each cgroup_subsys with _cgrp_subsys. * With the above, renaming subsys identifiers to match the userland visible names doesn't cause any naming conflicts. All non-matching identifiers are renamed to match the official names. cpu_cgroup -> cpu mem_cgroup -> memory perf -> perf_event * controllers no longer need to initialize ->subsys_id and ->name. They're generated in cgroup core and set automatically during boot. * Redundant cgroup_subsys declarations removed. * While updating BUG_ON()s in cgroup_init_early(), convert them to WARN()s. BUGging that early during boot is stupid - the kernel can't print anything, even through serial console and the trap handler doesn't even link stack frame properly for back-tracing. This patch doesn't introduce any behavior changes. v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs classid handling into core"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: "David S. Miller" <davem@davemloft.net> Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Ingo Molnar <mingo@redhat.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Thomas Graf <tgraf@suug.ch>
2014-02-08 19:36:58 +04:00
WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN,
"cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]);
ss->id = i;
cgroup: clean up cgroup_subsys names and initialization cgroup_subsys is a bit messier than it needs to be. * The name of a subsys can be different from its internal identifier defined in cgroup_subsys.h. Most subsystems use the matching name but three - cpu, memory and perf_event - use different ones. * cgroup_subsys_id enums are postfixed with _subsys_id and each cgroup_subsys is postfixed with _subsys. cgroup.h is widely included throughout various subsystems, it doesn't and shouldn't have claim on such generic names which don't have any qualifier indicating that they belong to cgroup. * cgroup_subsys->subsys_id should always equal the matching cgroup_subsys_id enum; however, we require each controller to initialize it and then BUG if they don't match, which is a bit silly. This patch cleans up cgroup_subsys names and initialization by doing the followings. * cgroup_subsys_id enums are now postfixed with _cgrp_id, and each cgroup_subsys with _cgrp_subsys. * With the above, renaming subsys identifiers to match the userland visible names doesn't cause any naming conflicts. All non-matching identifiers are renamed to match the official names. cpu_cgroup -> cpu mem_cgroup -> memory perf -> perf_event * controllers no longer need to initialize ->subsys_id and ->name. They're generated in cgroup core and set automatically during boot. * Redundant cgroup_subsys declarations removed. * While updating BUG_ON()s in cgroup_init_early(), convert them to WARN()s. BUGging that early during boot is stupid - the kernel can't print anything, even through serial console and the trap handler doesn't even link stack frame properly for back-tracing. This patch doesn't introduce any behavior changes. v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs classid handling into core"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: "David S. Miller" <davem@davemloft.net> Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Ingo Molnar <mingo@redhat.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Thomas Graf <tgraf@suug.ch>
2014-02-08 19:36:58 +04:00
ss->name = cgroup_subsys_name[i];
if (!ss->legacy_name)
ss->legacy_name = cgroup_subsys_name[i];
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
if (ss->early_init)
cgroup_init_subsys(ss, true);
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
return 0;
}
static u16 cgroup_disable_mask __initdata;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
/**
* cgroup_init - cgroup initialization
*
* Register cgroup filesystem and /proc file, and initialize
* any subsystems that didn't request early init.
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
*/
int __init cgroup_init(void)
{
struct cgroup_subsys *ss;
int ssid;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16);
BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem));
BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files));
BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files));
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
mutex_lock(&cgroup_mutex);
/*
* Add init_css_set to the hash table so that dfl_root can link to
* it during init.
*/
hash_add(css_set_table, &init_css_set.hlist,
css_set_hash(init_css_set.subsys));
BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0));
mutex_unlock(&cgroup_mutex);
for_each_subsys(ss, ssid) {
if (ss->early_init) {
struct cgroup_subsys_state *css =
init_css_set.subsys[ss->id];
css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2,
GFP_KERNEL);
BUG_ON(css->id < 0);
} else {
cgroup_init_subsys(ss, false);
}
list_add_tail(&init_css_set.e_cset_node[ssid],
&cgrp_dfl_root.cgrp.e_csets[ssid]);
/*
* Setting dfl_root subsys_mask needs to consider the
* disabled flag and cftype registration needs kmalloc,
* both of which aren't available during early_init.
*/
if (cgroup_disable_mask & (1 << ssid)) {
static_branch_disable(cgroup_subsys_enabled_key[ssid]);
printk(KERN_INFO "Disabling %s control group subsystem\n",
ss->name);
cgroup: distinguish the default and legacy hierarchies when handling cftypes Until now, cftype arrays carried files for both the default and legacy hierarchies and the files which needed to be used on only one of them were flagged with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE. This gets confusing very quickly and we may end up exposing interface files to the default hierarchy without thinking it through. This patch makes cgroup core provide separate sets of interfaces for cftype handling so that the cftypes for the default and legacy hierarchies are clearly distinguished. The previous two patches renamed the existing ones so that they clearly indicate that they're for the legacy hierarchies. This patch adds the interface for the default hierarchy and apply them selectively depending on the hierarchy type. * cftypes added through cgroup_subsys->dfl_cftypes and cgroup_add_dfl_cftypes() only show up on the default hierarchy. * cftypes added through cgroup_subsys->legacy_cftypes and cgroup_add_legacy_cftypes() only show up on the legacy hierarchies. * cgroup_subsys->dfl_cftypes and ->legacy_cftypes can point to the same array for the cases where the interface files are identical on both types of hierarchies. * This makes all the existing subsystem interface files legacy-only by default and all subsystems will have no interface file created when enabled on the default hierarchy. Each subsystem should explicitly review and compose the interface for the default hierarchy. * A boot param "cgroup__DEVEL__legacy_files_on_dfl" is added which makes subsystems which haven't decided the interface files for the default hierarchy to present the legacy files on the default hierarchy so that its behavior on the default hierarchy can be tested. As the awkward name suggests, this is for development only. * memcg's CFTYPE_INSANE on "use_hierarchy" is noop now as the whole array isn't used on the default hierarchy. The flag is removed. v2: Updated documentation for cgroup__DEVEL__legacy_files_on_dfl. v3: Clear CFTYPE_ONLY_ON_DFL and CFTYPE_INSANE when cfts are removed as suggested by Li. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Aristeu Rozanski <aris@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2014-07-15 19:05:10 +04:00
continue;
}
cgroup: distinguish the default and legacy hierarchies when handling cftypes Until now, cftype arrays carried files for both the default and legacy hierarchies and the files which needed to be used on only one of them were flagged with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE. This gets confusing very quickly and we may end up exposing interface files to the default hierarchy without thinking it through. This patch makes cgroup core provide separate sets of interfaces for cftype handling so that the cftypes for the default and legacy hierarchies are clearly distinguished. The previous two patches renamed the existing ones so that they clearly indicate that they're for the legacy hierarchies. This patch adds the interface for the default hierarchy and apply them selectively depending on the hierarchy type. * cftypes added through cgroup_subsys->dfl_cftypes and cgroup_add_dfl_cftypes() only show up on the default hierarchy. * cftypes added through cgroup_subsys->legacy_cftypes and cgroup_add_legacy_cftypes() only show up on the legacy hierarchies. * cgroup_subsys->dfl_cftypes and ->legacy_cftypes can point to the same array for the cases where the interface files are identical on both types of hierarchies. * This makes all the existing subsystem interface files legacy-only by default and all subsystems will have no interface file created when enabled on the default hierarchy. Each subsystem should explicitly review and compose the interface for the default hierarchy. * A boot param "cgroup__DEVEL__legacy_files_on_dfl" is added which makes subsystems which haven't decided the interface files for the default hierarchy to present the legacy files on the default hierarchy so that its behavior on the default hierarchy can be tested. As the awkward name suggests, this is for development only. * memcg's CFTYPE_INSANE on "use_hierarchy" is noop now as the whole array isn't used on the default hierarchy. The flag is removed. v2: Updated documentation for cgroup__DEVEL__legacy_files_on_dfl. v3: Clear CFTYPE_ONLY_ON_DFL and CFTYPE_INSANE when cfts are removed as suggested by Li. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Aristeu Rozanski <aris@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2014-07-15 19:05:10 +04:00
if (cgroup_ssid_no_v1(ssid))
printk(KERN_INFO "Disabling %s control group subsystem in v1 mounts\n",
ss->name);
cgroup: distinguish the default and legacy hierarchies when handling cftypes Until now, cftype arrays carried files for both the default and legacy hierarchies and the files which needed to be used on only one of them were flagged with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE. This gets confusing very quickly and we may end up exposing interface files to the default hierarchy without thinking it through. This patch makes cgroup core provide separate sets of interfaces for cftype handling so that the cftypes for the default and legacy hierarchies are clearly distinguished. The previous two patches renamed the existing ones so that they clearly indicate that they're for the legacy hierarchies. This patch adds the interface for the default hierarchy and apply them selectively depending on the hierarchy type. * cftypes added through cgroup_subsys->dfl_cftypes and cgroup_add_dfl_cftypes() only show up on the default hierarchy. * cftypes added through cgroup_subsys->legacy_cftypes and cgroup_add_legacy_cftypes() only show up on the legacy hierarchies. * cgroup_subsys->dfl_cftypes and ->legacy_cftypes can point to the same array for the cases where the interface files are identical on both types of hierarchies. * This makes all the existing subsystem interface files legacy-only by default and all subsystems will have no interface file created when enabled on the default hierarchy. Each subsystem should explicitly review and compose the interface for the default hierarchy. * A boot param "cgroup__DEVEL__legacy_files_on_dfl" is added which makes subsystems which haven't decided the interface files for the default hierarchy to present the legacy files on the default hierarchy so that its behavior on the default hierarchy can be tested. As the awkward name suggests, this is for development only. * memcg's CFTYPE_INSANE on "use_hierarchy" is noop now as the whole array isn't used on the default hierarchy. The flag is removed. v2: Updated documentation for cgroup__DEVEL__legacy_files_on_dfl. v3: Clear CFTYPE_ONLY_ON_DFL and CFTYPE_INSANE when cfts are removed as suggested by Li. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Aristeu Rozanski <aris@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2014-07-15 19:05:10 +04:00
cgrp_dfl_root.subsys_mask |= 1 << ss->id;
if (!ss->dfl_cftypes)
cgrp_dfl_inhibit_ss_mask |= 1 << ss->id;
cgroup: distinguish the default and legacy hierarchies when handling cftypes Until now, cftype arrays carried files for both the default and legacy hierarchies and the files which needed to be used on only one of them were flagged with either CFTYPE_ONLY_ON_DFL or CFTYPE_INSANE. This gets confusing very quickly and we may end up exposing interface files to the default hierarchy without thinking it through. This patch makes cgroup core provide separate sets of interfaces for cftype handling so that the cftypes for the default and legacy hierarchies are clearly distinguished. The previous two patches renamed the existing ones so that they clearly indicate that they're for the legacy hierarchies. This patch adds the interface for the default hierarchy and apply them selectively depending on the hierarchy type. * cftypes added through cgroup_subsys->dfl_cftypes and cgroup_add_dfl_cftypes() only show up on the default hierarchy. * cftypes added through cgroup_subsys->legacy_cftypes and cgroup_add_legacy_cftypes() only show up on the legacy hierarchies. * cgroup_subsys->dfl_cftypes and ->legacy_cftypes can point to the same array for the cases where the interface files are identical on both types of hierarchies. * This makes all the existing subsystem interface files legacy-only by default and all subsystems will have no interface file created when enabled on the default hierarchy. Each subsystem should explicitly review and compose the interface for the default hierarchy. * A boot param "cgroup__DEVEL__legacy_files_on_dfl" is added which makes subsystems which haven't decided the interface files for the default hierarchy to present the legacy files on the default hierarchy so that its behavior on the default hierarchy can be tested. As the awkward name suggests, this is for development only. * memcg's CFTYPE_INSANE on "use_hierarchy" is noop now as the whole array isn't used on the default hierarchy. The flag is removed. v2: Updated documentation for cgroup__DEVEL__legacy_files_on_dfl. v3: Clear CFTYPE_ONLY_ON_DFL and CFTYPE_INSANE when cfts are removed as suggested by Li. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Aristeu Rozanski <aris@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
2014-07-15 19:05:10 +04:00
if (ss->dfl_cftypes == ss->legacy_cftypes) {
WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes));
} else {
WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes));
WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes));
}
if (ss->bind)
ss->bind(init_css_set.subsys[ssid]);
}
/* init_css_set.subsys[] has been updated, re-hash */
hash_del(&init_css_set.hlist);
hash_add(css_set_table, &init_css_set.hlist,
css_set_hash(init_css_set.subsys));
WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup"));
WARN_ON(register_filesystem(&cgroup_fs_type));
WARN_ON(register_filesystem(&cgroup2_fs_type));
WARN_ON(!proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations));
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
return 0;
Task Control Groups: basic task cgroup framework Generic Process Control Groups -------------------------- There have recently been various proposals floating around for resource management/accounting and other task grouping subsystems in the kernel, including ResGroups, User BeanCounters, NSProxy cgroups, and others. These all need the basic abstraction of being able to group together multiple processes in an aggregate, in order to track/limit the resources permitted to those processes, or control other behaviour of the processes, and all implement this grouping in different ways. This patchset provides a framework for tracking and grouping processes into arbitrary "cgroups" and assigning arbitrary state to those groupings, in order to control the behaviour of the cgroup as an aggregate. The intention is that the various resource management and virtualization/cgroup efforts can also become task cgroup clients, with the result that: - the userspace APIs are (somewhat) normalised - it's easier to test e.g. the ResGroups CPU controller in conjunction with the BeanCounters memory controller, or use either of them as the resource-control portion of a virtual server system. - the additional kernel footprint of any of the competing resource management systems is substantially reduced, since it doesn't need to provide process grouping/containment, hence improving their chances of getting into the kernel This patch: Add the main task cgroups framework - the cgroup filesystem, and the basic structures for tracking membership and associating subsystem state objects to tasks. Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:30 +04:00
}
cgroup: use a dedicated workqueue for cgroup destruction Since be44562613851 ("cgroup: remove synchronize_rcu() from cgroup_diput()"), cgroup destruction path makes use of workqueue. css freeing is performed from a work item from that point on and a later commit, ea15f8ccdb430 ("cgroup: split cgroup destruction into two steps"), moves css offlining to workqueue too. As cgroup destruction isn't depended upon for memory reclaim, the destruction work items were put on the system_wq; unfortunately, some controller may block in the destruction path for considerable duration while holding cgroup_mutex. As large part of destruction path is synchronized through cgroup_mutex, when combined with high rate of cgroup removals, this has potential to fill up system_wq's max_active of 256. Also, it turns out that memcg's css destruction path ends up queueing and waiting for work items on system_wq through work_on_cpu(). If such operation happens while system_wq is fully occupied by cgroup destruction work items, work_on_cpu() can't make forward progress because system_wq is full and other destruction work items on system_wq can't make forward progress because the work item waiting for work_on_cpu() is holding cgroup_mutex, leading to deadlock. This can be fixed by queueing destruction work items on a separate workqueue. This patch creates a dedicated workqueue - cgroup_destroy_wq - for this purpose. As these work items shouldn't have inter-dependencies and mostly serialized by cgroup_mutex anyway, giving high concurrency level doesn't buy anything and the workqueue's @max_active is set to 1 so that destruction work items are executed one by one on each CPU. Hugh Dickins: Because cgroup_init() is run before init_workqueues(), cgroup_destroy_wq can't be allocated from cgroup_init(). Do it from a separate core_initcall(). In the future, we probably want to reorder so that workqueue init happens before cgroup_init(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Hugh Dickins <hughd@google.com> Reported-by: Shawn Bohrer <shawn.bohrer@gmail.com> Link: http://lkml.kernel.org/r/20131111220626.GA7509@sbohrermbp13-local.rgmadvisors.com Link: http://lkml.kernel.org/g/alpine.LNX.2.00.1310301606080.2333@eggly.anvils Cc: stable@vger.kernel.org # v3.9+
2013-11-23 02:14:39 +04:00
static int __init cgroup_wq_init(void)
{
/*
* There isn't much point in executing destruction path in
* parallel. Good chunk is serialized with cgroup_mutex anyway.
* Use 1 for @max_active.
cgroup: use a dedicated workqueue for cgroup destruction Since be44562613851 ("cgroup: remove synchronize_rcu() from cgroup_diput()"), cgroup destruction path makes use of workqueue. css freeing is performed from a work item from that point on and a later commit, ea15f8ccdb430 ("cgroup: split cgroup destruction into two steps"), moves css offlining to workqueue too. As cgroup destruction isn't depended upon for memory reclaim, the destruction work items were put on the system_wq; unfortunately, some controller may block in the destruction path for considerable duration while holding cgroup_mutex. As large part of destruction path is synchronized through cgroup_mutex, when combined with high rate of cgroup removals, this has potential to fill up system_wq's max_active of 256. Also, it turns out that memcg's css destruction path ends up queueing and waiting for work items on system_wq through work_on_cpu(). If such operation happens while system_wq is fully occupied by cgroup destruction work items, work_on_cpu() can't make forward progress because system_wq is full and other destruction work items on system_wq can't make forward progress because the work item waiting for work_on_cpu() is holding cgroup_mutex, leading to deadlock. This can be fixed by queueing destruction work items on a separate workqueue. This patch creates a dedicated workqueue - cgroup_destroy_wq - for this purpose. As these work items shouldn't have inter-dependencies and mostly serialized by cgroup_mutex anyway, giving high concurrency level doesn't buy anything and the workqueue's @max_active is set to 1 so that destruction work items are executed one by one on each CPU. Hugh Dickins: Because cgroup_init() is run before init_workqueues(), cgroup_destroy_wq can't be allocated from cgroup_init(). Do it from a separate core_initcall(). In the future, we probably want to reorder so that workqueue init happens before cgroup_init(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Hugh Dickins <hughd@google.com> Reported-by: Shawn Bohrer <shawn.bohrer@gmail.com> Link: http://lkml.kernel.org/r/20131111220626.GA7509@sbohrermbp13-local.rgmadvisors.com Link: http://lkml.kernel.org/g/alpine.LNX.2.00.1310301606080.2333@eggly.anvils Cc: stable@vger.kernel.org # v3.9+
2013-11-23 02:14:39 +04:00
*
* We would prefer to do this in cgroup_init() above, but that
* is called before init_workqueues(): so leave this until after.
*/
cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
cgroup: use a dedicated workqueue for cgroup destruction Since be44562613851 ("cgroup: remove synchronize_rcu() from cgroup_diput()"), cgroup destruction path makes use of workqueue. css freeing is performed from a work item from that point on and a later commit, ea15f8ccdb430 ("cgroup: split cgroup destruction into two steps"), moves css offlining to workqueue too. As cgroup destruction isn't depended upon for memory reclaim, the destruction work items were put on the system_wq; unfortunately, some controller may block in the destruction path for considerable duration while holding cgroup_mutex. As large part of destruction path is synchronized through cgroup_mutex, when combined with high rate of cgroup removals, this has potential to fill up system_wq's max_active of 256. Also, it turns out that memcg's css destruction path ends up queueing and waiting for work items on system_wq through work_on_cpu(). If such operation happens while system_wq is fully occupied by cgroup destruction work items, work_on_cpu() can't make forward progress because system_wq is full and other destruction work items on system_wq can't make forward progress because the work item waiting for work_on_cpu() is holding cgroup_mutex, leading to deadlock. This can be fixed by queueing destruction work items on a separate workqueue. This patch creates a dedicated workqueue - cgroup_destroy_wq - for this purpose. As these work items shouldn't have inter-dependencies and mostly serialized by cgroup_mutex anyway, giving high concurrency level doesn't buy anything and the workqueue's @max_active is set to 1 so that destruction work items are executed one by one on each CPU. Hugh Dickins: Because cgroup_init() is run before init_workqueues(), cgroup_destroy_wq can't be allocated from cgroup_init(). Do it from a separate core_initcall(). In the future, we probably want to reorder so that workqueue init happens before cgroup_init(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Hugh Dickins <hughd@google.com> Reported-by: Shawn Bohrer <shawn.bohrer@gmail.com> Link: http://lkml.kernel.org/r/20131111220626.GA7509@sbohrermbp13-local.rgmadvisors.com Link: http://lkml.kernel.org/g/alpine.LNX.2.00.1310301606080.2333@eggly.anvils Cc: stable@vger.kernel.org # v3.9+
2013-11-23 02:14:39 +04:00
BUG_ON(!cgroup_destroy_wq);
2013-11-29 19:42:58 +04:00
/*
* Used to destroy pidlists and separate to serve as flush domain.
* Cap @max_active to 1 too.
*/
cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
0, 1);
BUG_ON(!cgroup_pidlist_destroy_wq);
cgroup: use a dedicated workqueue for cgroup destruction Since be44562613851 ("cgroup: remove synchronize_rcu() from cgroup_diput()"), cgroup destruction path makes use of workqueue. css freeing is performed from a work item from that point on and a later commit, ea15f8ccdb430 ("cgroup: split cgroup destruction into two steps"), moves css offlining to workqueue too. As cgroup destruction isn't depended upon for memory reclaim, the destruction work items were put on the system_wq; unfortunately, some controller may block in the destruction path for considerable duration while holding cgroup_mutex. As large part of destruction path is synchronized through cgroup_mutex, when combined with high rate of cgroup removals, this has potential to fill up system_wq's max_active of 256. Also, it turns out that memcg's css destruction path ends up queueing and waiting for work items on system_wq through work_on_cpu(). If such operation happens while system_wq is fully occupied by cgroup destruction work items, work_on_cpu() can't make forward progress because system_wq is full and other destruction work items on system_wq can't make forward progress because the work item waiting for work_on_cpu() is holding cgroup_mutex, leading to deadlock. This can be fixed by queueing destruction work items on a separate workqueue. This patch creates a dedicated workqueue - cgroup_destroy_wq - for this purpose. As these work items shouldn't have inter-dependencies and mostly serialized by cgroup_mutex anyway, giving high concurrency level doesn't buy anything and the workqueue's @max_active is set to 1 so that destruction work items are executed one by one on each CPU. Hugh Dickins: Because cgroup_init() is run before init_workqueues(), cgroup_destroy_wq can't be allocated from cgroup_init(). Do it from a separate core_initcall(). In the future, we probably want to reorder so that workqueue init happens before cgroup_init(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Hugh Dickins <hughd@google.com> Reported-by: Shawn Bohrer <shawn.bohrer@gmail.com> Link: http://lkml.kernel.org/r/20131111220626.GA7509@sbohrermbp13-local.rgmadvisors.com Link: http://lkml.kernel.org/g/alpine.LNX.2.00.1310301606080.2333@eggly.anvils Cc: stable@vger.kernel.org # v3.9+
2013-11-23 02:14:39 +04:00
return 0;
}
core_initcall(cgroup_wq_init);
/*
* proc_cgroup_show()
* - Print task's cgroup paths into seq_file, one line for each hierarchy
* - Used for /proc/<pid>/cgroup.
*/
int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *tsk)
{
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
char *buf, *path;
int retval;
struct cgroup_root *root;
retval = -ENOMEM;
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
buf = kmalloc(PATH_MAX, GFP_KERNEL);
if (!buf)
goto out;
mutex_lock(&cgroup_mutex);
spin_lock_bh(&css_set_lock);
for_each_root(root) {
struct cgroup_subsys *ss;
struct cgroup *cgrp;
int ssid, count = 0;
if (root == &cgrp_dfl_root && !cgrp_dfl_visible)
continue;
seq_printf(m, "%d:", root->hierarchy_id);
if (root != &cgrp_dfl_root)
for_each_subsys(ss, ssid)
if (root->subsys_mask & (1 << ssid))
seq_printf(m, "%s%s", count++ ? "," : "",
ss->legacy_name);
if (strlen(root->name))
seq_printf(m, "%sname=%s", count ? "," : "",
root->name);
seq_putc(m, ':');
cgroup: keep zombies associated with their original cgroups cgroup_exit() is called when a task exits and disassociates the exiting task from its cgroups and half-attach it to the root cgroup. This is unnecessary and undesirable. No controller actually needs an exiting task to be disassociated with non-root cgroups. Both cpu and perf_event controllers update the association to the root cgroup from their exit callbacks just to keep consistent with the cgroup core behavior. Also, this disassociation makes it difficult to track resources held by zombies or determine where the zombies came from. Currently, pids controller is completely broken as it uncharges on exit and zombies always escape the resource restriction. With cgroup association being reset on exit, fixing it is pretty painful. There's no reason to reset cgroup membership on exit. The zombie can be removed from its css_set so that it doesn't show up on "cgroup.procs" and thus can't be migrated or interfere with cgroup removal. It can still pin and point to the css_set so that its cgroup membership is maintained. This patch makes cgroup core keep zombies associated with their cgroups at the time of exit. * Previous patches decoupled populated_cnt tracking from css_set lifetime, so a dying task can be simply unlinked from its css_set while pinning and pointing to the css_set. This keeps css_set association from task side alive while hiding it from "cgroup.procs" and populated_cnt tracking. The css_set reference is dropped when the task_struct is freed. * ->exit() callback no longer needs the css arguments as the associated css never changes once PF_EXITING is set. Removed. * cpu and perf_events controllers no longer need ->exit() callbacks. There's no reason to explicitly switch away on exit. The final schedule out is enough. The callbacks are removed. * On traditional hierarchies, nothing changes. "/proc/PID/cgroup" still reports "/" for all zombies. On the default hierarchy, "/proc/PID/cgroup" keeps reporting the cgroup that the task belonged to at the time of exit. If the cgroup gets removed before the task is reaped, " (deleted)" is appended. v2: Build brekage due to missing dummy cgroup_free() when !CONFIG_CGROUP fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
2015-10-15 23:41:53 +03:00
cgrp = task_cgroup_from_root(tsk, root);
cgroup: keep zombies associated with their original cgroups cgroup_exit() is called when a task exits and disassociates the exiting task from its cgroups and half-attach it to the root cgroup. This is unnecessary and undesirable. No controller actually needs an exiting task to be disassociated with non-root cgroups. Both cpu and perf_event controllers update the association to the root cgroup from their exit callbacks just to keep consistent with the cgroup core behavior. Also, this disassociation makes it difficult to track resources held by zombies or determine where the zombies came from. Currently, pids controller is completely broken as it uncharges on exit and zombies always escape the resource restriction. With cgroup association being reset on exit, fixing it is pretty painful. There's no reason to reset cgroup membership on exit. The zombie can be removed from its css_set so that it doesn't show up on "cgroup.procs" and thus can't be migrated or interfere with cgroup removal. It can still pin and point to the css_set so that its cgroup membership is maintained. This patch makes cgroup core keep zombies associated with their cgroups at the time of exit. * Previous patches decoupled populated_cnt tracking from css_set lifetime, so a dying task can be simply unlinked from its css_set while pinning and pointing to the css_set. This keeps css_set association from task side alive while hiding it from "cgroup.procs" and populated_cnt tracking. The css_set reference is dropped when the task_struct is freed. * ->exit() callback no longer needs the css arguments as the associated css never changes once PF_EXITING is set. Removed. * cpu and perf_events controllers no longer need ->exit() callbacks. There's no reason to explicitly switch away on exit. The final schedule out is enough. The callbacks are removed. * On traditional hierarchies, nothing changes. "/proc/PID/cgroup" still reports "/" for all zombies. On the default hierarchy, "/proc/PID/cgroup" keeps reporting the cgroup that the task belonged to at the time of exit. If the cgroup gets removed before the task is reaped, " (deleted)" is appended. v2: Build brekage due to missing dummy cgroup_free() when !CONFIG_CGROUP fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
2015-10-15 23:41:53 +03:00
/*
* On traditional hierarchies, all zombie tasks show up as
* belonging to the root cgroup. On the default hierarchy,
* while a zombie doesn't show up in "cgroup.procs" and
* thus can't be migrated, its /proc/PID/cgroup keeps
* reporting the cgroup it belonged to before exiting. If
* the cgroup is removed before the zombie is reaped,
* " (deleted)" is appended to the cgroup path.
*/
if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) {
path = cgroup_path(cgrp, buf, PATH_MAX);
if (!path) {
retval = -ENAMETOOLONG;
goto out_unlock;
}
} else {
path = "/";
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
}
cgroup: keep zombies associated with their original cgroups cgroup_exit() is called when a task exits and disassociates the exiting task from its cgroups and half-attach it to the root cgroup. This is unnecessary and undesirable. No controller actually needs an exiting task to be disassociated with non-root cgroups. Both cpu and perf_event controllers update the association to the root cgroup from their exit callbacks just to keep consistent with the cgroup core behavior. Also, this disassociation makes it difficult to track resources held by zombies or determine where the zombies came from. Currently, pids controller is completely broken as it uncharges on exit and zombies always escape the resource restriction. With cgroup association being reset on exit, fixing it is pretty painful. There's no reason to reset cgroup membership on exit. The zombie can be removed from its css_set so that it doesn't show up on "cgroup.procs" and thus can't be migrated or interfere with cgroup removal. It can still pin and point to the css_set so that its cgroup membership is maintained. This patch makes cgroup core keep zombies associated with their cgroups at the time of exit. * Previous patches decoupled populated_cnt tracking from css_set lifetime, so a dying task can be simply unlinked from its css_set while pinning and pointing to the css_set. This keeps css_set association from task side alive while hiding it from "cgroup.procs" and populated_cnt tracking. The css_set reference is dropped when the task_struct is freed. * ->exit() callback no longer needs the css arguments as the associated css never changes once PF_EXITING is set. Removed. * cpu and perf_events controllers no longer need ->exit() callbacks. There's no reason to explicitly switch away on exit. The final schedule out is enough. The callbacks are removed. * On traditional hierarchies, nothing changes. "/proc/PID/cgroup" still reports "/" for all zombies. On the default hierarchy, "/proc/PID/cgroup" keeps reporting the cgroup that the task belonged to at the time of exit. If the cgroup gets removed before the task is reaped, " (deleted)" is appended. v2: Build brekage due to missing dummy cgroup_free() when !CONFIG_CGROUP fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
2015-10-15 23:41:53 +03:00
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
seq_puts(m, path);
cgroup: keep zombies associated with their original cgroups cgroup_exit() is called when a task exits and disassociates the exiting task from its cgroups and half-attach it to the root cgroup. This is unnecessary and undesirable. No controller actually needs an exiting task to be disassociated with non-root cgroups. Both cpu and perf_event controllers update the association to the root cgroup from their exit callbacks just to keep consistent with the cgroup core behavior. Also, this disassociation makes it difficult to track resources held by zombies or determine where the zombies came from. Currently, pids controller is completely broken as it uncharges on exit and zombies always escape the resource restriction. With cgroup association being reset on exit, fixing it is pretty painful. There's no reason to reset cgroup membership on exit. The zombie can be removed from its css_set so that it doesn't show up on "cgroup.procs" and thus can't be migrated or interfere with cgroup removal. It can still pin and point to the css_set so that its cgroup membership is maintained. This patch makes cgroup core keep zombies associated with their cgroups at the time of exit. * Previous patches decoupled populated_cnt tracking from css_set lifetime, so a dying task can be simply unlinked from its css_set while pinning and pointing to the css_set. This keeps css_set association from task side alive while hiding it from "cgroup.procs" and populated_cnt tracking. The css_set reference is dropped when the task_struct is freed. * ->exit() callback no longer needs the css arguments as the associated css never changes once PF_EXITING is set. Removed. * cpu and perf_events controllers no longer need ->exit() callbacks. There's no reason to explicitly switch away on exit. The final schedule out is enough. The callbacks are removed. * On traditional hierarchies, nothing changes. "/proc/PID/cgroup" still reports "/" for all zombies. On the default hierarchy, "/proc/PID/cgroup" keeps reporting the cgroup that the task belonged to at the time of exit. If the cgroup gets removed before the task is reaped, " (deleted)" is appended. v2: Build brekage due to missing dummy cgroup_free() when !CONFIG_CGROUP fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
2015-10-15 23:41:53 +03:00
if (cgroup_on_dfl(cgrp) && cgroup_is_dead(cgrp))
seq_puts(m, " (deleted)\n");
else
seq_putc(m, '\n');
}
retval = 0;
out_unlock:
spin_unlock_bh(&css_set_lock);
mutex_unlock(&cgroup_mutex);
kfree(buf);
out:
return retval;
}
/* Display information about each subsystem and each hierarchy */
static int proc_cgroupstats_show(struct seq_file *m, void *v)
{
struct cgroup_subsys *ss;
int i;
cgroups: add cgroup support for enabling controllers at boot time The effects of cgroup_disable=foo are: - foo isn't auto-mounted if you mount all cgroups in a single hierarchy - foo isn't visible as an individually mountable subsystem As a result there will only ever be one call to foo->create(), at init time; all processes will stay in this group, and the group will never be mounted on a visible hierarchy. Any additional effects (e.g. not allocating metadata) are up to the foo subsystem. This doesn't handle early_init subsystems (their "disabled" bit isn't set be, but it could easily be extended to do so if any of the early_init systems wanted it - I think it would just involve some nastier parameter processing since it would occur before the command-line argument parser had been run. Hugh said: Ballpark figures, I'm trying to get this question out rather than processing the exact numbers: CONFIG_CGROUP_MEM_RES_CTLR adds 15% overhead to the affected paths, booting with cgroup_disable=memory cuts that back to 1% overhead (due to slightly bigger struct page). I'm no expert on distros, they may have no interest whatever in CONFIG_CGROUP_MEM_RES_CTLR=y; and the rest of us can easily build with or without it, or apply the cgroup_disable=memory patches. Unix bench's execl test result on x86_64 was == just after boot without mounting any cgroup fs.== mem_cgorup=off : Execl Throughput 43.0 3150.1 732.6 mem_cgroup=on : Execl Throughput 43.0 2932.6 682.0 == [lizf@cn.fujitsu.com: fix boot option parsing] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Sudhir Kumar <skumar@linux.vnet.ibm.com> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-05 01:29:57 +04:00
seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
cgroups: revamp subsys array This patch series provides the ability for cgroup subsystems to be compiled as modules both within and outside the kernel tree. This is mainly useful for classifiers and subsystems that hook into components that are already modules. cls_cgroup and blkio-cgroup serve as the example use cases for this feature. It provides an interface cgroup_load_subsys() and cgroup_unload_subsys() which modular subsystems can use to register and depart during runtime. The net_cls classifier subsystem serves as the example for a subsystem which can be converted into a module using these changes. Patch #1 sets up the subsys[] array so its contents can be dynamic as modules appear and (eventually) disappear. Iterations over the array are modified to handle when subsystems are absent, and the dynamic section of the array is protected by cgroup_mutex. Patch #2 implements an interface for modules to load subsystems, called cgroup_load_subsys, similar to cgroup_init_subsys, and adds a module pointer in struct cgroup_subsys. Patch #3 adds a mechanism for unloading modular subsystems, which includes a more advanced rework of the rudimentary reference counting introduced in patch 2. Patch #4 modifies the net_cls subsystem, which already had some module declarations, to be configurable as a module, which also serves as a simple proof-of-concept. Part of implementing patches 2 and 4 involved updating css pointers in each css_set when the module appears or leaves. In doing this, it was discovered that css_sets always remain linked to the dummy cgroup, regardless of whether or not any subsystems are actually bound to it (i.e., not mounted on an actual hierarchy). The subsystem loading and unloading code therefore should keep in mind the special cases where the added subsystem is the only one in the dummy cgroup (and therefore all css_sets need to be linked back into it) and where the removed subsys was the only one in the dummy cgroup (and therefore all css_sets should be unlinked from it) - however, as all css_sets always stay attached to the dummy cgroup anyway, these cases are ignored. Any fix that addresses this issue should also make sure these cases are addressed in the subsystem loading and unloading code. This patch: Make subsys[] able to be dynamically populated to support modular subsystems This patch reworks the way the subsys[] array is used so that subsystems can register themselves after boot time, and enables the internals of cgroups to be able to handle when subsystems are not present or may appear/disappear. Signed-off-by: Ben Blum <bblum@andrew.cmu.edu> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-11 02:22:07 +03:00
/*
* ideally we don't want subsystems moving around while we do this.
* cgroup_mutex is also necessary to guarantee an atomic snapshot of
* subsys/hierarchy state.
*/
mutex_lock(&cgroup_mutex);
for_each_subsys(ss, i)
seq_printf(m, "%s\t%d\t%d\t%d\n",
ss->legacy_name, ss->root->hierarchy_id,
atomic_read(&ss->root->nr_cgrps),
cgroup_ssid_enabled(i));
mutex_unlock(&cgroup_mutex);
return 0;
}
static int cgroupstats_open(struct inode *inode, struct file *file)
{
return single_open(file, proc_cgroupstats_show, NULL);
}
static const struct file_operations proc_cgroupstats_operations = {
.open = cgroupstats_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
/**
cgroup: update how a newly forked task gets associated with css_set When a new process is forked, cgroup_fork() associates it with the css_set of its parent but doesn't link it into it. After the new process is linked to tasklist, cgroup_post_fork() does the linking. This is problematic for cgroup_transfer_tasks() as there's no way to tell whether there are tasks which are pointing to a css_set but not linked yet. It is impossible to implement an operation which transfer all tasks of a cgroup to another and the current cgroup_transfer_tasks() can easily be tricked into leaving a newly forked process behind if it gets called between cgroup_fork() and cgroup_post_fork(). Let's make association with a css_set and linking atomic by moving it to cgroup_post_fork(). cgroup_fork() sets child->cgroups to init_css_set as a placeholder and cgroup_post_fork() is updated to perform both the association with the parent's cgroup and linking there. This means that a newly created task will point to init_css_set without holding a ref to it much like what it does on the exit path. Empty cg_list is used to indicate that the task isn't holding a ref to the associated css_set. This fixes an actual bug with cgroup_transfer_tasks(); however, I'm not marking it for -stable. The whole thing is broken in multiple other ways which require invasive updates to fix and I don't think it's worthwhile to bother with backporting this particular one. Fortunately, the only user is cpuset and these bugs don't crash the machine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
* cgroup_fork - initialize cgroup related fields during copy_process()
* @child: pointer to task_struct of forking parent process.
*
cgroup: update how a newly forked task gets associated with css_set When a new process is forked, cgroup_fork() associates it with the css_set of its parent but doesn't link it into it. After the new process is linked to tasklist, cgroup_post_fork() does the linking. This is problematic for cgroup_transfer_tasks() as there's no way to tell whether there are tasks which are pointing to a css_set but not linked yet. It is impossible to implement an operation which transfer all tasks of a cgroup to another and the current cgroup_transfer_tasks() can easily be tricked into leaving a newly forked process behind if it gets called between cgroup_fork() and cgroup_post_fork(). Let's make association with a css_set and linking atomic by moving it to cgroup_post_fork(). cgroup_fork() sets child->cgroups to init_css_set as a placeholder and cgroup_post_fork() is updated to perform both the association with the parent's cgroup and linking there. This means that a newly created task will point to init_css_set without holding a ref to it much like what it does on the exit path. Empty cg_list is used to indicate that the task isn't holding a ref to the associated css_set. This fixes an actual bug with cgroup_transfer_tasks(); however, I'm not marking it for -stable. The whole thing is broken in multiple other ways which require invasive updates to fix and I don't think it's worthwhile to bother with backporting this particular one. Fortunately, the only user is cpuset and these bugs don't crash the machine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
* A task is associated with the init_css_set until cgroup_post_fork()
* attaches it to the parent's css_set. Empty cg_list indicates that
* @child isn't holding reference to its css_set.
*/
void cgroup_fork(struct task_struct *child)
{
cgroup: update how a newly forked task gets associated with css_set When a new process is forked, cgroup_fork() associates it with the css_set of its parent but doesn't link it into it. After the new process is linked to tasklist, cgroup_post_fork() does the linking. This is problematic for cgroup_transfer_tasks() as there's no way to tell whether there are tasks which are pointing to a css_set but not linked yet. It is impossible to implement an operation which transfer all tasks of a cgroup to another and the current cgroup_transfer_tasks() can easily be tricked into leaving a newly forked process behind if it gets called between cgroup_fork() and cgroup_post_fork(). Let's make association with a css_set and linking atomic by moving it to cgroup_post_fork(). cgroup_fork() sets child->cgroups to init_css_set as a placeholder and cgroup_post_fork() is updated to perform both the association with the parent's cgroup and linking there. This means that a newly created task will point to init_css_set without holding a ref to it much like what it does on the exit path. Empty cg_list is used to indicate that the task isn't holding a ref to the associated css_set. This fixes an actual bug with cgroup_transfer_tasks(); however, I'm not marking it for -stable. The whole thing is broken in multiple other ways which require invasive updates to fix and I don't think it's worthwhile to bother with backporting this particular one. Fortunately, the only user is cpuset and these bugs don't crash the machine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
RCU_INIT_POINTER(child->cgroups, &init_css_set);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
INIT_LIST_HEAD(&child->cg_list);
}
/**
* cgroup_can_fork - called on a new task before the process is exposed
* @child: the task in question.
*
* This calls the subsystem can_fork() callbacks. If the can_fork() callback
* returns an error, the fork aborts with that error code. This allows for
* a cgroup subsystem to conditionally allow or deny new forks.
*/
int cgroup_can_fork(struct task_struct *child)
{
struct cgroup_subsys *ss;
int i, j, ret;
do_each_subsys_mask(ss, i, have_canfork_callback) {
ret = ss->can_fork(child);
if (ret)
goto out_revert;
} while_each_subsys_mask();
return 0;
out_revert:
for_each_subsys(ss, j) {
if (j >= i)
break;
if (ss->cancel_fork)
ss->cancel_fork(child);
}
return ret;
}
/**
* cgroup_cancel_fork - called if a fork failed after cgroup_can_fork()
* @child: the task in question
*
* This calls the cancel_fork() callbacks if a fork failed *after*
* cgroup_can_fork() succeded.
*/
void cgroup_cancel_fork(struct task_struct *child)
{
struct cgroup_subsys *ss;
int i;
for_each_subsys(ss, i)
if (ss->cancel_fork)
ss->cancel_fork(child);
}
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
/**
* cgroup_post_fork - called on a new task after adding it to the task list
* @child: the task in question
*
* Adds the task to the list running through its css_set if necessary and
* call the subsystem fork() callbacks. Has to be after the task is
* visible on the task list in case we race with the first call to
* cgroup_task_iter_start() - to guarantee that the new task ends up on its
* list.
*/
void cgroup_post_fork(struct task_struct *child)
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
{
struct cgroup_subsys *ss;
int i;
cgroup: Walk task list under tasklist_lock in cgroup_enable_task_cg_list Walking through the tasklist in cgroup_enable_task_cg_list() inside an RCU read side critical section is not enough because: - RCU is not (yet) safe against while_each_thread() - If we use only RCU, a forking task that has passed cgroup_post_fork() without seeing use_task_css_set_links == 1 is not guaranteed to have its child immediately visible in the tasklist if we walk through it remotely with RCU. In this case it will be missing in its css_set's task list. Thus we need to traverse the list (unfortunately) under the tasklist_lock. It makes us safe against while_each_thread() and also make sure we see all forked task that have been added to the tasklist. As a secondary effect, reading and writing use_task_css_set_links are now well ordered against tasklist traversing and modification. The new layout is: CPU 0 CPU 1 use_task_css_set_links = 1 write_lock(tasklist_lock) read_lock(tasklist_lock) add task to tasklist do_each_thread() { write_unlock(tasklist_lock) add thread to css set links if (use_task_css_set_links) } while_each_thread() add thread to css set links read_unlock(tasklist_lock) If CPU 0 traverse the list after the task has been added to the tasklist then it is correctly added to the css set links. OTOH if CPU 0 traverse the tasklist before the new task had the opportunity to be added to the tasklist because it was too early in the fork process, then CPU 1 catches up and add the task to the css set links after it added the task to the tasklist. The right value of use_task_css_set_links is guaranteed to be visible from CPU 1 due to the LOCK/UNLOCK implicit barrier properties: the read_unlock on CPU 0 makes the write on use_task_css_set_links happening and the write_lock on CPU 1 make the read of use_task_css_set_links that comes afterward to return the correct value. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Mandeep Singh Baines <msb@chromium.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-02-08 06:37:27 +04:00
/*
* This may race against cgroup_enable_task_cg_lists(). As that
cgroup: update how a newly forked task gets associated with css_set When a new process is forked, cgroup_fork() associates it with the css_set of its parent but doesn't link it into it. After the new process is linked to tasklist, cgroup_post_fork() does the linking. This is problematic for cgroup_transfer_tasks() as there's no way to tell whether there are tasks which are pointing to a css_set but not linked yet. It is impossible to implement an operation which transfer all tasks of a cgroup to another and the current cgroup_transfer_tasks() can easily be tricked into leaving a newly forked process behind if it gets called between cgroup_fork() and cgroup_post_fork(). Let's make association with a css_set and linking atomic by moving it to cgroup_post_fork(). cgroup_fork() sets child->cgroups to init_css_set as a placeholder and cgroup_post_fork() is updated to perform both the association with the parent's cgroup and linking there. This means that a newly created task will point to init_css_set without holding a ref to it much like what it does on the exit path. Empty cg_list is used to indicate that the task isn't holding a ref to the associated css_set. This fixes an actual bug with cgroup_transfer_tasks(); however, I'm not marking it for -stable. The whole thing is broken in multiple other ways which require invasive updates to fix and I don't think it's worthwhile to bother with backporting this particular one. Fortunately, the only user is cpuset and these bugs don't crash the machine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
* function sets use_task_css_set_links before grabbing
* tasklist_lock and we just went through tasklist_lock to add
* @child, it's guaranteed that either we see the set
* use_task_css_set_links or cgroup_enable_task_cg_lists() sees
* @child during its iteration.
*
* If we won the race, @child is associated with %current's
* css_set. Grabbing css_set_lock guarantees both that the
cgroup: update how a newly forked task gets associated with css_set When a new process is forked, cgroup_fork() associates it with the css_set of its parent but doesn't link it into it. After the new process is linked to tasklist, cgroup_post_fork() does the linking. This is problematic for cgroup_transfer_tasks() as there's no way to tell whether there are tasks which are pointing to a css_set but not linked yet. It is impossible to implement an operation which transfer all tasks of a cgroup to another and the current cgroup_transfer_tasks() can easily be tricked into leaving a newly forked process behind if it gets called between cgroup_fork() and cgroup_post_fork(). Let's make association with a css_set and linking atomic by moving it to cgroup_post_fork(). cgroup_fork() sets child->cgroups to init_css_set as a placeholder and cgroup_post_fork() is updated to perform both the association with the parent's cgroup and linking there. This means that a newly created task will point to init_css_set without holding a ref to it much like what it does on the exit path. Empty cg_list is used to indicate that the task isn't holding a ref to the associated css_set. This fixes an actual bug with cgroup_transfer_tasks(); however, I'm not marking it for -stable. The whole thing is broken in multiple other ways which require invasive updates to fix and I don't think it's worthwhile to bother with backporting this particular one. Fortunately, the only user is cpuset and these bugs don't crash the machine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
* association is stable, and, on completion of the parent's
* migration, @child is visible in the source of migration or
* already in the destination cgroup. This guarantee is necessary
* when implementing operations which need to migrate all tasks of
* a cgroup to another.
*
* Note that if we lose to cgroup_enable_task_cg_lists(), @child
cgroup: update how a newly forked task gets associated with css_set When a new process is forked, cgroup_fork() associates it with the css_set of its parent but doesn't link it into it. After the new process is linked to tasklist, cgroup_post_fork() does the linking. This is problematic for cgroup_transfer_tasks() as there's no way to tell whether there are tasks which are pointing to a css_set but not linked yet. It is impossible to implement an operation which transfer all tasks of a cgroup to another and the current cgroup_transfer_tasks() can easily be tricked into leaving a newly forked process behind if it gets called between cgroup_fork() and cgroup_post_fork(). Let's make association with a css_set and linking atomic by moving it to cgroup_post_fork(). cgroup_fork() sets child->cgroups to init_css_set as a placeholder and cgroup_post_fork() is updated to perform both the association with the parent's cgroup and linking there. This means that a newly created task will point to init_css_set without holding a ref to it much like what it does on the exit path. Empty cg_list is used to indicate that the task isn't holding a ref to the associated css_set. This fixes an actual bug with cgroup_transfer_tasks(); however, I'm not marking it for -stable. The whole thing is broken in multiple other ways which require invasive updates to fix and I don't think it's worthwhile to bother with backporting this particular one. Fortunately, the only user is cpuset and these bugs don't crash the machine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
* will remain in init_css_set. This is safe because all tasks are
* in the init_css_set before cg_links is enabled and there's no
* operation which transfers all tasks out of init_css_set.
cgroup: Walk task list under tasklist_lock in cgroup_enable_task_cg_list Walking through the tasklist in cgroup_enable_task_cg_list() inside an RCU read side critical section is not enough because: - RCU is not (yet) safe against while_each_thread() - If we use only RCU, a forking task that has passed cgroup_post_fork() without seeing use_task_css_set_links == 1 is not guaranteed to have its child immediately visible in the tasklist if we walk through it remotely with RCU. In this case it will be missing in its css_set's task list. Thus we need to traverse the list (unfortunately) under the tasklist_lock. It makes us safe against while_each_thread() and also make sure we see all forked task that have been added to the tasklist. As a secondary effect, reading and writing use_task_css_set_links are now well ordered against tasklist traversing and modification. The new layout is: CPU 0 CPU 1 use_task_css_set_links = 1 write_lock(tasklist_lock) read_lock(tasklist_lock) add task to tasklist do_each_thread() { write_unlock(tasklist_lock) add thread to css set links if (use_task_css_set_links) } while_each_thread() add thread to css set links read_unlock(tasklist_lock) If CPU 0 traverse the list after the task has been added to the tasklist then it is correctly added to the css set links. OTOH if CPU 0 traverse the tasklist before the new task had the opportunity to be added to the tasklist because it was too early in the fork process, then CPU 1 catches up and add the task to the css set links after it added the task to the tasklist. The right value of use_task_css_set_links is guaranteed to be visible from CPU 1 due to the LOCK/UNLOCK implicit barrier properties: the read_unlock on CPU 0 makes the write on use_task_css_set_links happening and the write_lock on CPU 1 make the read of use_task_css_set_links that comes afterward to return the correct value. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Mandeep Singh Baines <msb@chromium.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-02-08 06:37:27 +04:00
*/
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
if (use_task_css_set_links) {
cgroup: update how a newly forked task gets associated with css_set When a new process is forked, cgroup_fork() associates it with the css_set of its parent but doesn't link it into it. After the new process is linked to tasklist, cgroup_post_fork() does the linking. This is problematic for cgroup_transfer_tasks() as there's no way to tell whether there are tasks which are pointing to a css_set but not linked yet. It is impossible to implement an operation which transfer all tasks of a cgroup to another and the current cgroup_transfer_tasks() can easily be tricked into leaving a newly forked process behind if it gets called between cgroup_fork() and cgroup_post_fork(). Let's make association with a css_set and linking atomic by moving it to cgroup_post_fork(). cgroup_fork() sets child->cgroups to init_css_set as a placeholder and cgroup_post_fork() is updated to perform both the association with the parent's cgroup and linking there. This means that a newly created task will point to init_css_set without holding a ref to it much like what it does on the exit path. Empty cg_list is used to indicate that the task isn't holding a ref to the associated css_set. This fixes an actual bug with cgroup_transfer_tasks(); however, I'm not marking it for -stable. The whole thing is broken in multiple other ways which require invasive updates to fix and I don't think it's worthwhile to bother with backporting this particular one. Fortunately, the only user is cpuset and these bugs don't crash the machine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
struct css_set *cset;
spin_lock_bh(&css_set_lock);
cset = task_css_set(current);
cgroup: update how a newly forked task gets associated with css_set When a new process is forked, cgroup_fork() associates it with the css_set of its parent but doesn't link it into it. After the new process is linked to tasklist, cgroup_post_fork() does the linking. This is problematic for cgroup_transfer_tasks() as there's no way to tell whether there are tasks which are pointing to a css_set but not linked yet. It is impossible to implement an operation which transfer all tasks of a cgroup to another and the current cgroup_transfer_tasks() can easily be tricked into leaving a newly forked process behind if it gets called between cgroup_fork() and cgroup_post_fork(). Let's make association with a css_set and linking atomic by moving it to cgroup_post_fork(). cgroup_fork() sets child->cgroups to init_css_set as a placeholder and cgroup_post_fork() is updated to perform both the association with the parent's cgroup and linking there. This means that a newly created task will point to init_css_set without holding a ref to it much like what it does on the exit path. Empty cg_list is used to indicate that the task isn't holding a ref to the associated css_set. This fixes an actual bug with cgroup_transfer_tasks(); however, I'm not marking it for -stable. The whole thing is broken in multiple other ways which require invasive updates to fix and I don't think it's worthwhile to bother with backporting this particular one. Fortunately, the only user is cpuset and these bugs don't crash the machine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
if (list_empty(&child->cg_list)) {
get_css_set(cset);
css_set_move_task(child, NULL, cset, false);
cgroup: update how a newly forked task gets associated with css_set When a new process is forked, cgroup_fork() associates it with the css_set of its parent but doesn't link it into it. After the new process is linked to tasklist, cgroup_post_fork() does the linking. This is problematic for cgroup_transfer_tasks() as there's no way to tell whether there are tasks which are pointing to a css_set but not linked yet. It is impossible to implement an operation which transfer all tasks of a cgroup to another and the current cgroup_transfer_tasks() can easily be tricked into leaving a newly forked process behind if it gets called between cgroup_fork() and cgroup_post_fork(). Let's make association with a css_set and linking atomic by moving it to cgroup_post_fork(). cgroup_fork() sets child->cgroups to init_css_set as a placeholder and cgroup_post_fork() is updated to perform both the association with the parent's cgroup and linking there. This means that a newly created task will point to init_css_set without holding a ref to it much like what it does on the exit path. Empty cg_list is used to indicate that the task isn't holding a ref to the associated css_set. This fixes an actual bug with cgroup_transfer_tasks(); however, I'm not marking it for -stable. The whole thing is broken in multiple other ways which require invasive updates to fix and I don't think it's worthwhile to bother with backporting this particular one. Fortunately, the only user is cpuset and these bugs don't crash the machine. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:03 +04:00
}
spin_unlock_bh(&css_set_lock);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
}
/*
* Call ss->fork(). This must happen after @child is linked on
* css_set; otherwise, @child might change state between ->fork()
* and addition to css_set.
*/
do_each_subsys_mask(ss, i, have_fork_callback) {
ss->fork(child);
} while_each_subsys_mask();
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
}
/**
* cgroup_exit - detach cgroup from exiting task
* @tsk: pointer to task_struct of exiting process
*
* Description: Detach cgroup from @tsk and release it.
*
* Note that cgroups marked notify_on_release force every task in
* them to take the global cgroup_mutex mutex when exiting.
* This could impact scaling on very large systems. Be reluctant to
* use notify_on_release cgroups where very high task exit scaling
* is required on large systems.
*
* We set the exiting tasks cgroup to the root cgroup (top_cgroup). We
* call cgroup_exit() while the task is still competent to handle
* notify_on_release(), then leave the task attached to the root cgroup in
* each hierarchy for the remainder of its exit. No need to bother with
* init_css_set refcnting. init_css_set never goes away and we can't race
* with migration path - PF_EXITING is visible to migration path.
*/
void cgroup_exit(struct task_struct *tsk)
{
struct cgroup_subsys *ss;
struct css_set *cset;
int i;
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
/*
* Unlink from @tsk from its css_set. As migration path can't race
* with us, we can check css_set and cg_list without synchronization.
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
*/
cset = task_css_set(tsk);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
if (!list_empty(&tsk->cg_list)) {
spin_lock_bh(&css_set_lock);
css_set_move_task(tsk, cset, NULL, false);
spin_unlock_bh(&css_set_lock);
cgroup: keep zombies associated with their original cgroups cgroup_exit() is called when a task exits and disassociates the exiting task from its cgroups and half-attach it to the root cgroup. This is unnecessary and undesirable. No controller actually needs an exiting task to be disassociated with non-root cgroups. Both cpu and perf_event controllers update the association to the root cgroup from their exit callbacks just to keep consistent with the cgroup core behavior. Also, this disassociation makes it difficult to track resources held by zombies or determine where the zombies came from. Currently, pids controller is completely broken as it uncharges on exit and zombies always escape the resource restriction. With cgroup association being reset on exit, fixing it is pretty painful. There's no reason to reset cgroup membership on exit. The zombie can be removed from its css_set so that it doesn't show up on "cgroup.procs" and thus can't be migrated or interfere with cgroup removal. It can still pin and point to the css_set so that its cgroup membership is maintained. This patch makes cgroup core keep zombies associated with their cgroups at the time of exit. * Previous patches decoupled populated_cnt tracking from css_set lifetime, so a dying task can be simply unlinked from its css_set while pinning and pointing to the css_set. This keeps css_set association from task side alive while hiding it from "cgroup.procs" and populated_cnt tracking. The css_set reference is dropped when the task_struct is freed. * ->exit() callback no longer needs the css arguments as the associated css never changes once PF_EXITING is set. Removed. * cpu and perf_events controllers no longer need ->exit() callbacks. There's no reason to explicitly switch away on exit. The final schedule out is enough. The callbacks are removed. * On traditional hierarchies, nothing changes. "/proc/PID/cgroup" still reports "/" for all zombies. On the default hierarchy, "/proc/PID/cgroup" keeps reporting the cgroup that the task belonged to at the time of exit. If the cgroup gets removed before the task is reaped, " (deleted)" is appended. v2: Build brekage due to missing dummy cgroup_free() when !CONFIG_CGROUP fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
2015-10-15 23:41:53 +03:00
} else {
get_css_set(cset);
Task Control Groups: shared cgroup subsystem group arrays Replace the struct css_set embedded in task_struct with a pointer; all tasks that have the same set of memberships across all hierarchies will share a css_set object, and will be linked via their css_sets field to the "tasks" list_head in the css_set. Assuming that many tasks share the same cgroup assignments, this reduces overall space usage and keeps the size of the task_struct down (three pointers added to task_struct compared to a non-cgroups kernel, no matter how many subsystems are registered). [akpm@linux-foundation.org: fix a printk] [akpm@linux-foundation.org: build fix] Signed-off-by: Paul Menage <menage@google.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Paul Jackson <pj@sgi.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-19 10:39:36 +04:00
}
/* see cgroup_post_fork() for details */
do_each_subsys_mask(ss, i, have_exit_callback) {
cgroup: keep zombies associated with their original cgroups cgroup_exit() is called when a task exits and disassociates the exiting task from its cgroups and half-attach it to the root cgroup. This is unnecessary and undesirable. No controller actually needs an exiting task to be disassociated with non-root cgroups. Both cpu and perf_event controllers update the association to the root cgroup from their exit callbacks just to keep consistent with the cgroup core behavior. Also, this disassociation makes it difficult to track resources held by zombies or determine where the zombies came from. Currently, pids controller is completely broken as it uncharges on exit and zombies always escape the resource restriction. With cgroup association being reset on exit, fixing it is pretty painful. There's no reason to reset cgroup membership on exit. The zombie can be removed from its css_set so that it doesn't show up on "cgroup.procs" and thus can't be migrated or interfere with cgroup removal. It can still pin and point to the css_set so that its cgroup membership is maintained. This patch makes cgroup core keep zombies associated with their cgroups at the time of exit. * Previous patches decoupled populated_cnt tracking from css_set lifetime, so a dying task can be simply unlinked from its css_set while pinning and pointing to the css_set. This keeps css_set association from task side alive while hiding it from "cgroup.procs" and populated_cnt tracking. The css_set reference is dropped when the task_struct is freed. * ->exit() callback no longer needs the css arguments as the associated css never changes once PF_EXITING is set. Removed. * cpu and perf_events controllers no longer need ->exit() callbacks. There's no reason to explicitly switch away on exit. The final schedule out is enough. The callbacks are removed. * On traditional hierarchies, nothing changes. "/proc/PID/cgroup" still reports "/" for all zombies. On the default hierarchy, "/proc/PID/cgroup" keeps reporting the cgroup that the task belonged to at the time of exit. If the cgroup gets removed before the task is reaped, " (deleted)" is appended. v2: Build brekage due to missing dummy cgroup_free() when !CONFIG_CGROUP fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
2015-10-15 23:41:53 +03:00
ss->exit(tsk);
} while_each_subsys_mask();
cgroup: keep zombies associated with their original cgroups cgroup_exit() is called when a task exits and disassociates the exiting task from its cgroups and half-attach it to the root cgroup. This is unnecessary and undesirable. No controller actually needs an exiting task to be disassociated with non-root cgroups. Both cpu and perf_event controllers update the association to the root cgroup from their exit callbacks just to keep consistent with the cgroup core behavior. Also, this disassociation makes it difficult to track resources held by zombies or determine where the zombies came from. Currently, pids controller is completely broken as it uncharges on exit and zombies always escape the resource restriction. With cgroup association being reset on exit, fixing it is pretty painful. There's no reason to reset cgroup membership on exit. The zombie can be removed from its css_set so that it doesn't show up on "cgroup.procs" and thus can't be migrated or interfere with cgroup removal. It can still pin and point to the css_set so that its cgroup membership is maintained. This patch makes cgroup core keep zombies associated with their cgroups at the time of exit. * Previous patches decoupled populated_cnt tracking from css_set lifetime, so a dying task can be simply unlinked from its css_set while pinning and pointing to the css_set. This keeps css_set association from task side alive while hiding it from "cgroup.procs" and populated_cnt tracking. The css_set reference is dropped when the task_struct is freed. * ->exit() callback no longer needs the css arguments as the associated css never changes once PF_EXITING is set. Removed. * cpu and perf_events controllers no longer need ->exit() callbacks. There's no reason to explicitly switch away on exit. The final schedule out is enough. The callbacks are removed. * On traditional hierarchies, nothing changes. "/proc/PID/cgroup" still reports "/" for all zombies. On the default hierarchy, "/proc/PID/cgroup" keeps reporting the cgroup that the task belonged to at the time of exit. If the cgroup gets removed before the task is reaped, " (deleted)" is appended. v2: Build brekage due to missing dummy cgroup_free() when !CONFIG_CGROUP fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
2015-10-15 23:41:53 +03:00
}
cgroup: keep zombies associated with their original cgroups cgroup_exit() is called when a task exits and disassociates the exiting task from its cgroups and half-attach it to the root cgroup. This is unnecessary and undesirable. No controller actually needs an exiting task to be disassociated with non-root cgroups. Both cpu and perf_event controllers update the association to the root cgroup from their exit callbacks just to keep consistent with the cgroup core behavior. Also, this disassociation makes it difficult to track resources held by zombies or determine where the zombies came from. Currently, pids controller is completely broken as it uncharges on exit and zombies always escape the resource restriction. With cgroup association being reset on exit, fixing it is pretty painful. There's no reason to reset cgroup membership on exit. The zombie can be removed from its css_set so that it doesn't show up on "cgroup.procs" and thus can't be migrated or interfere with cgroup removal. It can still pin and point to the css_set so that its cgroup membership is maintained. This patch makes cgroup core keep zombies associated with their cgroups at the time of exit. * Previous patches decoupled populated_cnt tracking from css_set lifetime, so a dying task can be simply unlinked from its css_set while pinning and pointing to the css_set. This keeps css_set association from task side alive while hiding it from "cgroup.procs" and populated_cnt tracking. The css_set reference is dropped when the task_struct is freed. * ->exit() callback no longer needs the css arguments as the associated css never changes once PF_EXITING is set. Removed. * cpu and perf_events controllers no longer need ->exit() callbacks. There's no reason to explicitly switch away on exit. The final schedule out is enough. The callbacks are removed. * On traditional hierarchies, nothing changes. "/proc/PID/cgroup" still reports "/" for all zombies. On the default hierarchy, "/proc/PID/cgroup" keeps reporting the cgroup that the task belonged to at the time of exit. If the cgroup gets removed before the task is reaped, " (deleted)" is appended. v2: Build brekage due to missing dummy cgroup_free() when !CONFIG_CGROUP fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
2015-10-15 23:41:53 +03:00
void cgroup_free(struct task_struct *task)
{
struct css_set *cset = task_css_set(task);
struct cgroup_subsys *ss;
int ssid;
do_each_subsys_mask(ss, ssid, have_free_callback) {
ss->free(task);
} while_each_subsys_mask();
cgroup: keep zombies associated with their original cgroups cgroup_exit() is called when a task exits and disassociates the exiting task from its cgroups and half-attach it to the root cgroup. This is unnecessary and undesirable. No controller actually needs an exiting task to be disassociated with non-root cgroups. Both cpu and perf_event controllers update the association to the root cgroup from their exit callbacks just to keep consistent with the cgroup core behavior. Also, this disassociation makes it difficult to track resources held by zombies or determine where the zombies came from. Currently, pids controller is completely broken as it uncharges on exit and zombies always escape the resource restriction. With cgroup association being reset on exit, fixing it is pretty painful. There's no reason to reset cgroup membership on exit. The zombie can be removed from its css_set so that it doesn't show up on "cgroup.procs" and thus can't be migrated or interfere with cgroup removal. It can still pin and point to the css_set so that its cgroup membership is maintained. This patch makes cgroup core keep zombies associated with their cgroups at the time of exit. * Previous patches decoupled populated_cnt tracking from css_set lifetime, so a dying task can be simply unlinked from its css_set while pinning and pointing to the css_set. This keeps css_set association from task side alive while hiding it from "cgroup.procs" and populated_cnt tracking. The css_set reference is dropped when the task_struct is freed. * ->exit() callback no longer needs the css arguments as the associated css never changes once PF_EXITING is set. Removed. * cpu and perf_events controllers no longer need ->exit() callbacks. There's no reason to explicitly switch away on exit. The final schedule out is enough. The callbacks are removed. * On traditional hierarchies, nothing changes. "/proc/PID/cgroup" still reports "/" for all zombies. On the default hierarchy, "/proc/PID/cgroup" keeps reporting the cgroup that the task belonged to at the time of exit. If the cgroup gets removed before the task is reaped, " (deleted)" is appended. v2: Build brekage due to missing dummy cgroup_free() when !CONFIG_CGROUP fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
2015-10-15 23:41:53 +03:00
put_css_set(cset);
}
static void check_for_release(struct cgroup *cgrp)
{
if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
!css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
schedule_work(&cgrp->release_agent_work);
}
/*
* Notify userspace when a cgroup is released, by running the
* configured release agent with the name of the cgroup (path
* relative to the root of cgroup file system) as the argument.
*
* Most likely, this user command will try to rmdir this cgroup.
*
* This races with the possibility that some other task will be
* attached to this cgroup before it is removed, or that some other
* user task will 'mkdir' a child cgroup of this cgroup. That's ok.
* The presumed 'rmdir' will fail quietly if this cgroup is no longer
* unused, and this cgroup will be reprieved from its death sentence,
* to continue to serve a useful existence. Next time it's released,
* we will get notified again, if it still has 'notify_on_release' set.
*
* The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
* means only wait until the task is successfully execve()'d. The
* separate release agent task is forked by call_usermodehelper(),
* then control in this thread returns here, without waiting for the
* release agent task. We don't bother to wait because the caller of
* this routine has no use for the exit status of the release agent
* task, so no sense holding our caller up for that.
*/
static void cgroup_release_agent(struct work_struct *work)
{
struct cgroup *cgrp =
container_of(work, struct cgroup, release_agent_work);
char *pathbuf = NULL, *agentbuf = NULL, *path;
char *argv[3], *envp[3];
mutex_lock(&cgroup_mutex);
pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
if (!pathbuf || !agentbuf)
goto out;
path = cgroup_path(cgrp, pathbuf, PATH_MAX);
if (!path)
goto out;
argv[0] = agentbuf;
argv[1] = path;
argv[2] = NULL;
/* minimal command environment */
envp[0] = "HOME=/";
envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
envp[2] = NULL;
mutex_unlock(&cgroup_mutex);
call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
goto out_free;
out:
mutex_unlock(&cgroup_mutex);
out_free:
kfree(agentbuf);
kfree(pathbuf);
}
cgroups: add cgroup support for enabling controllers at boot time The effects of cgroup_disable=foo are: - foo isn't auto-mounted if you mount all cgroups in a single hierarchy - foo isn't visible as an individually mountable subsystem As a result there will only ever be one call to foo->create(), at init time; all processes will stay in this group, and the group will never be mounted on a visible hierarchy. Any additional effects (e.g. not allocating metadata) are up to the foo subsystem. This doesn't handle early_init subsystems (their "disabled" bit isn't set be, but it could easily be extended to do so if any of the early_init systems wanted it - I think it would just involve some nastier parameter processing since it would occur before the command-line argument parser had been run. Hugh said: Ballpark figures, I'm trying to get this question out rather than processing the exact numbers: CONFIG_CGROUP_MEM_RES_CTLR adds 15% overhead to the affected paths, booting with cgroup_disable=memory cuts that back to 1% overhead (due to slightly bigger struct page). I'm no expert on distros, they may have no interest whatever in CONFIG_CGROUP_MEM_RES_CTLR=y; and the rest of us can easily build with or without it, or apply the cgroup_disable=memory patches. Unix bench's execl test result on x86_64 was == just after boot without mounting any cgroup fs.== mem_cgorup=off : Execl Throughput 43.0 3150.1 732.6 mem_cgroup=on : Execl Throughput 43.0 2932.6 682.0 == [lizf@cn.fujitsu.com: fix boot option parsing] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Sudhir Kumar <skumar@linux.vnet.ibm.com> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-05 01:29:57 +04:00
static int __init cgroup_disable(char *str)
{
struct cgroup_subsys *ss;
cgroups: add cgroup support for enabling controllers at boot time The effects of cgroup_disable=foo are: - foo isn't auto-mounted if you mount all cgroups in a single hierarchy - foo isn't visible as an individually mountable subsystem As a result there will only ever be one call to foo->create(), at init time; all processes will stay in this group, and the group will never be mounted on a visible hierarchy. Any additional effects (e.g. not allocating metadata) are up to the foo subsystem. This doesn't handle early_init subsystems (their "disabled" bit isn't set be, but it could easily be extended to do so if any of the early_init systems wanted it - I think it would just involve some nastier parameter processing since it would occur before the command-line argument parser had been run. Hugh said: Ballpark figures, I'm trying to get this question out rather than processing the exact numbers: CONFIG_CGROUP_MEM_RES_CTLR adds 15% overhead to the affected paths, booting with cgroup_disable=memory cuts that back to 1% overhead (due to slightly bigger struct page). I'm no expert on distros, they may have no interest whatever in CONFIG_CGROUP_MEM_RES_CTLR=y; and the rest of us can easily build with or without it, or apply the cgroup_disable=memory patches. Unix bench's execl test result on x86_64 was == just after boot without mounting any cgroup fs.== mem_cgorup=off : Execl Throughput 43.0 3150.1 732.6 mem_cgroup=on : Execl Throughput 43.0 2932.6 682.0 == [lizf@cn.fujitsu.com: fix boot option parsing] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Sudhir Kumar <skumar@linux.vnet.ibm.com> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-05 01:29:57 +04:00
char *token;
int i;
cgroups: add cgroup support for enabling controllers at boot time The effects of cgroup_disable=foo are: - foo isn't auto-mounted if you mount all cgroups in a single hierarchy - foo isn't visible as an individually mountable subsystem As a result there will only ever be one call to foo->create(), at init time; all processes will stay in this group, and the group will never be mounted on a visible hierarchy. Any additional effects (e.g. not allocating metadata) are up to the foo subsystem. This doesn't handle early_init subsystems (their "disabled" bit isn't set be, but it could easily be extended to do so if any of the early_init systems wanted it - I think it would just involve some nastier parameter processing since it would occur before the command-line argument parser had been run. Hugh said: Ballpark figures, I'm trying to get this question out rather than processing the exact numbers: CONFIG_CGROUP_MEM_RES_CTLR adds 15% overhead to the affected paths, booting with cgroup_disable=memory cuts that back to 1% overhead (due to slightly bigger struct page). I'm no expert on distros, they may have no interest whatever in CONFIG_CGROUP_MEM_RES_CTLR=y; and the rest of us can easily build with or without it, or apply the cgroup_disable=memory patches. Unix bench's execl test result on x86_64 was == just after boot without mounting any cgroup fs.== mem_cgorup=off : Execl Throughput 43.0 3150.1 732.6 mem_cgroup=on : Execl Throughput 43.0 2932.6 682.0 == [lizf@cn.fujitsu.com: fix boot option parsing] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Sudhir Kumar <skumar@linux.vnet.ibm.com> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-05 01:29:57 +04:00
while ((token = strsep(&str, ",")) != NULL) {
if (!*token)
continue;
cgroup: Remove CGROUP_BUILTIN_SUBSYS_COUNT CGROUP_BUILTIN_SUBSYS_COUNT is used as start index or stop index when looping over the subsys array looking either at the builtin or the module subsystems. Since all the builtin subsystems have an id which is lower then CGROUP_BUILTIN_SUBSYS_COUNT we know that any module will have an id larger than CGROUP_BUILTIN_SUBSYS_COUNT. In short the ids are sorted. We are about to change id assignment to happen only at compile time later in this series. That means we can't rely on the above trick since all ids will always be defined at compile time. Furthermore, ordering the builtin subsystems and the module subsystems is not really necessary. So we need a different way to know which subsystem is a builtin or a module one. We can use the subsys[]->module pointer for this. Any place where we need to know if a subsys is module we just check for the pointer. If it is NULL then the subsystem is a builtin one. With this we are able to drop the CGROUP_BUILTIN_SUBSYS_COUNT enum. Though we need to introduce a temporary placeholder so that we don't get a compilation error when only CONFIG_CGROUP is selected and no single controller. An empty enum definition is not valid. Later in this series we are able to remove the placeholder again. And with this change we get a fix for this: kernel/cgroup.c: In function ‘cgroup_load_subsys’: kernel/cgroup.c:4326:38: warning: array subscript is below array bounds [-Warray-bounds] when CONFIG_CGROUP=y and no built in controller was enabled. Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Cc: Gao feng <gaofeng@cn.fujitsu.com> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Cc: John Fastabend <john.r.fastabend@intel.com> Cc: netdev@vger.kernel.org Cc: cgroups@vger.kernel.org
2012-09-13 11:50:55 +04:00
for_each_subsys(ss, i) {
if (strcmp(token, ss->name) &&
strcmp(token, ss->legacy_name))
continue;
cgroup_disable_mask |= 1 << i;
cgroups: add cgroup support for enabling controllers at boot time The effects of cgroup_disable=foo are: - foo isn't auto-mounted if you mount all cgroups in a single hierarchy - foo isn't visible as an individually mountable subsystem As a result there will only ever be one call to foo->create(), at init time; all processes will stay in this group, and the group will never be mounted on a visible hierarchy. Any additional effects (e.g. not allocating metadata) are up to the foo subsystem. This doesn't handle early_init subsystems (their "disabled" bit isn't set be, but it could easily be extended to do so if any of the early_init systems wanted it - I think it would just involve some nastier parameter processing since it would occur before the command-line argument parser had been run. Hugh said: Ballpark figures, I'm trying to get this question out rather than processing the exact numbers: CONFIG_CGROUP_MEM_RES_CTLR adds 15% overhead to the affected paths, booting with cgroup_disable=memory cuts that back to 1% overhead (due to slightly bigger struct page). I'm no expert on distros, they may have no interest whatever in CONFIG_CGROUP_MEM_RES_CTLR=y; and the rest of us can easily build with or without it, or apply the cgroup_disable=memory patches. Unix bench's execl test result on x86_64 was == just after boot without mounting any cgroup fs.== mem_cgorup=off : Execl Throughput 43.0 3150.1 732.6 mem_cgroup=on : Execl Throughput 43.0 2932.6 682.0 == [lizf@cn.fujitsu.com: fix boot option parsing] Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Paul Menage <menage@google.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Sudhir Kumar <skumar@linux.vnet.ibm.com> Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-05 01:29:57 +04:00
}
}
return 1;
}
__setup("cgroup_disable=", cgroup_disable);
cgroup: CSS ID support Patch for Per-CSS(Cgroup Subsys State) ID and private hierarchy code. This patch attaches unique ID to each css and provides following. - css_lookup(subsys, id) returns pointer to struct cgroup_subysys_state of id. - css_get_next(subsys, id, rootid, depth, foundid) returns the next css under "root" by scanning When cgroup_subsys->use_id is set, an id for css is maintained. The cgroup framework only parepares - css_id of root css for subsys - id is automatically attached at creation of css. - id is *not* freed automatically. Because the cgroup framework don't know lifetime of cgroup_subsys_state. free_css_id() function is provided. This must be called by subsys. There are several reasons to develop this. - Saving space .... For example, memcg's swap_cgroup is array of pointers to cgroup. But it is not necessary to be very fast. By replacing pointers(8bytes per ent) to ID (2byes per ent), we can reduce much amount of memory usage. - Scanning without lock. CSS_ID provides "scan id under this ROOT" function. By this, scanning css under root can be written without locks. ex) do { rcu_read_lock(); next = cgroup_get_next(subsys, id, root, &found); /* check sanity of next here */ css_tryget(); rcu_read_unlock(); id = found + 1 } while(...) Characteristics: - Each css has unique ID under subsys. - Lifetime of ID is controlled by subsys. - css ID contains "ID" and "Depth in hierarchy" and stack of hierarchy - Allowed ID is 1-65535, ID 0 is UNUSED ID. Design Choices: - scan-by-ID v.s. scan-by-tree-walk. As /proc's pid scan does, scan-by-ID is robust when scanning is done by following kind of routine. scan -> rest a while(release a lock) -> conitunue from interrupted memcg's hierarchical reclaim does this. - When subsys->use_id is set, # of css in the system is limited to 65535. [bharata@linux.vnet.ibm.com: remove rcu_read_lock() from css_get_next()] Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Paul Menage <menage@google.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-03 03:57:25 +04:00
static int __init cgroup_no_v1(char *str)
{
struct cgroup_subsys *ss;
char *token;
int i;
while ((token = strsep(&str, ",")) != NULL) {
if (!*token)
continue;
if (!strcmp(token, "all")) {
cgroup_no_v1_mask = U16_MAX;
break;
}
for_each_subsys(ss, i) {
if (strcmp(token, ss->name) &&
strcmp(token, ss->legacy_name))
continue;
cgroup_no_v1_mask |= 1 << i;
}
}
return 1;
}
__setup("cgroup_no_v1=", cgroup_no_v1);
/**
* css_tryget_online_from_dir - get corresponding css from a cgroup dentry
* @dentry: directory dentry of interest
* @ss: subsystem of interest
*
* If @dentry is a directory for a cgroup which has @ss enabled on it, try
* to get the corresponding css and return it. If such css doesn't exist
* or can't be pinned, an ERR_PTR value is returned.
*/
struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
struct cgroup_subsys *ss)
{
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
struct file_system_type *s_type = dentry->d_sb->s_type;
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
struct cgroup_subsys_state *css = NULL;
struct cgroup *cgrp;
/* is @dentry a cgroup dir? */
if ((s_type != &cgroup_fs_type && s_type != &cgroup2_fs_type) ||
!kn || kernfs_type(kn) != KERNFS_DIR)
return ERR_PTR(-EBADF);
rcu_read_lock();
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
/*
* This path doesn't originate from kernfs and @kn could already
* have been or be removed at any point. @kn->priv is RCU
* protected for this access. See css_release_work_fn() for details.
cgroup: convert to kernfs cgroup filesystem code was derived from the original sysfs implementation which was heavily intertwined with vfs objects and locking with the goal of re-using the existing vfs infrastructure. That experiment turned out rather disastrous and sysfs switched, a long time ago, to distributed filesystem model where a separate representation is maintained which is queried by vfs. Unfortunately, cgroup stuck with the failed experiment all these years and accumulated even more problems over time. Locking and object lifetime management being entangled with vfs is probably the most egregious. vfs is never designed to be misused like this and cgroup ends up jumping through various convoluted dancing to make things work. Even then, operations across multiple cgroups can't be done safely as it'll deadlock with rename locking. Recently, kernfs is separated out from sysfs so that it can be used by users other than sysfs. This patch converts cgroup to use kernfs, which will bring the following benefits. * Separation from vfs internals. Locking and object lifetime management is contained in cgroup proper making things a lot simpler. This removes significant amount of locking convolutions, hairy object lifetime rules and the restriction on multi-cgroup operations. * Can drop a lot of code to implement filesystem interface as most are provided by kernfs. * Proper "severing" semantics, which allows controllers to not worry about lingering file accesses after offline. While the preceding patches did as much as possible to make the transition less painful, large part of the conversion has to be one discrete step making this patch rather large. The rest of the commit message lists notable changes in different areas. Overall ------- * vfs constructs replaced with kernfs ones. cgroup->dentry w/ ->kn, cgroupfs_root->sb w/ ->kf_root. * All dentry accessors are removed. Helpers to map from kernfs constructs are added. * All vfs plumbing around dentry, inode and bdi removed. * cgroup_mount() now directly looks for matching root and then proceeds to create a new one if not found. Synchronization and object lifetime ----------------------------------- * vfs inode locking removed. Among other things, this removes the need for the convolution in cgroup_cfts_commit(). Future patches will further simplify it. * vfs refcnting replaced with cgroup internal ones. cgroup->refcnt, cgroupfs_root->refcnt added. cgroup_put_root() now directly puts root->refcnt and when it reaches zero proceeds to destroy it thus merging cgroup_put_root() and the former cgroup_kill_sb(). Simliarly, cgroup_put() now directly schedules cgroup_free_rcu() when refcnt reaches zero. * Unlike before, kernfs objects don't hold onto cgroup objects. When cgroup destroys a kernfs node, all existing operations are drained and the association is broken immediately. The same for cgroupfs_roots and mounts. * All operations which come through kernfs guarantee that the associated cgroup is and stays valid for the duration of operation; however, there are two paths which need to find out the associated cgroup from dentry without going through kernfs - css_tryget_from_dir() and cgroupstats_build(). For these two, kernfs_node->priv is RCU managed so that they can dereference it under RCU read lock. File and directory handling --------------------------- * File and directory operations converted to kernfs_ops and kernfs_syscall_ops. * xattrs is implicitly supported by kernfs. No need to worry about it from cgroup. This means that "xattr" mount option is no longer necessary. A future patch will add a deprecated warning message when sane_behavior. * When cftype->max_write_len > PAGE_SIZE, it's necessary to make a private copy of one of the kernfs_ops to set its atomic_write_len. cftype->kf_ops is added and cgroup_init/exit_cftypes() are updated to handle it. * cftype->lockdep_key added so that kernfs lockdep annotation can be per cftype. * Inidividual file entries and open states are now managed by kernfs. No need to worry about them from cgroup. cfent, cgroup_open_file and their friends are removed. * kernfs_nodes are created deactivated and kernfs_activate() invocations added to places where creation of new nodes are committed. * cgroup_rmdir() uses kernfs_[un]break_active_protection() for self-removal. v2: - Li pointed out in an earlier patch that specifying "name=" during mount without subsystem specification should succeed if there's an existing hierarchy with a matching name although it should fail with -EINVAL if a new hierarchy should be created. Prior to the conversion, this used by handled by deferring failure from NULL return from cgroup_root_from_opts(), which was necessary because root was being created before checking for existing ones. Note that cgroup_root_from_opts() returned an ERR_PTR() value for error conditions which require immediate mount failure. As we now have separate search and creation steps, deferring failure from cgroup_root_from_opts() is no longer necessary. cgroup_root_from_opts() is updated to always return ERR_PTR() value on failure. - The logic to match existing roots is updated so that a mount attempt with a matching name but different subsys_mask are rejected. This was handled by a separate matching loop under the comment "Check for name clashes with existing mounts" but got lost during conversion. Merge the check into the main search loop. - Add __rcu __force casting in RCU_INIT_POINTER() in cgroup_destroy_locked() to avoid the sparse address space warning reported by kbuild test bot. Maybe we want an explicit interface to use kn->priv as RCU protected pointer? v3: Make CONFIG_CGROUPS select CONFIG_KERNFS. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Cc: kbuild test robot fengguang.wu@intel.com>
2014-02-11 20:52:49 +04:00
*/
cgrp = rcu_dereference(kn->priv);
if (cgrp)
css = cgroup_css(cgrp, ss);
if (!css || !css_tryget_online(css))
css = ERR_PTR(-ENOENT);
rcu_read_unlock();
return css;
}
/**
* css_from_id - lookup css by id
* @id: the cgroup id
* @ss: cgroup subsys to be looked into
*
* Returns the css if there's valid one with @id, otherwise returns NULL.
* Should be called under rcu_read_lock().
*/
struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
{
WARN_ON_ONCE(!rcu_read_lock_held());
return id > 0 ? idr_find(&ss->css_idr, id) : NULL;
}
/**
* cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path
* @path: path on the default hierarchy
*
* Find the cgroup at @path on the default hierarchy, increment its
* reference count and return it. Returns pointer to the found cgroup on
* success, ERR_PTR(-ENOENT) if @path doens't exist and ERR_PTR(-ENOTDIR)
* if @path points to a non-directory.
*/
struct cgroup *cgroup_get_from_path(const char *path)
{
struct kernfs_node *kn;
struct cgroup *cgrp;
mutex_lock(&cgroup_mutex);
kn = kernfs_walk_and_get(cgrp_dfl_root.cgrp.kn, path);
if (kn) {
if (kernfs_type(kn) == KERNFS_DIR) {
cgrp = kn->priv;
cgroup_get(cgrp);
} else {
cgrp = ERR_PTR(-ENOTDIR);
}
kernfs_put(kn);
} else {
cgrp = ERR_PTR(-ENOENT);
}
mutex_unlock(&cgroup_mutex);
return cgrp;
}
EXPORT_SYMBOL_GPL(cgroup_get_from_path);
sock, cgroup: add sock->sk_cgroup In cgroup v1, dealing with cgroup membership was difficult because the number of membership associations was unbound. As a result, cgroup v1 grew several controllers whose primary purpose is either tagging membership or pull in configuration knobs from other subsystems so that cgroup membership test can be avoided. net_cls and net_prio controllers are examples of the latter. They allow configuring network-specific attributes from cgroup side so that network subsystem can avoid testing cgroup membership; unfortunately, these are not only cumbersome but also problematic. Both net_cls and net_prio aren't properly hierarchical. Both inherit configuration from the parent on creation but there's no interaction afterwards. An ancestor doesn't restrict the behavior in its subtree in anyway and configuration changes aren't propagated downwards. Especially when combined with cgroup delegation, this is problematic because delegatees can mess up whatever network configuration implemented at the system level. net_prio would allow the delegatees to set whatever priority value regardless of CAP_NET_ADMIN and net_cls the same for classid. While it is possible to solve these issues from controller side by implementing hierarchical allowable ranges in both controllers, it would involve quite a bit of complexity in the controllers and further obfuscate network configuration as it becomes even more difficult to tell what's actually being configured looking from the network side. While not much can be done for v1 at this point, as membership handling is sane on cgroup v2, it'd be better to make cgroup matching behave like other network matches and classifiers than introducing further complications. In preparation, this patch updates sock->sk_cgrp_data handling so that it points to the v2 cgroup that sock was created in until either net_prio or net_cls is used. Once either of the two is used, sock->sk_cgrp_data reverts to its previous role of carrying prioidx and classid. This is to avoid adding yet another cgroup related field to struct sock. As the mode switching can happen at most once per boot, the switching mechanism is aimed at lowering hot path overhead. It may leak a finite, likely small, number of cgroup refs and report spurious prioidx or classid on switching; however, dynamic updates of prioidx and classid have always been racy and lossy - socks between creation and fd installation are never updated, config changes don't update existing sockets at all, and prioidx may index with dead and recycled cgroup IDs. Non-critical inaccuracies from small race windows won't make any noticeable difference. This patch doesn't make use of the pointer yet. The following patch will implement netfilter match for cgroup2 membership. v2: Use sock_cgroup_data to avoid inflating struct sock w/ another cgroup specific field. v3: Add comments explaining why sock_data_prioidx() and sock_data_classid() use different fallback values. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Daniel Wagner <daniel.wagner@bmw-carit.de> CC: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-08 01:38:53 +03:00
/*
* sock->sk_cgrp_data handling. For more info, see sock_cgroup_data
* definition in cgroup-defs.h.
*/
#ifdef CONFIG_SOCK_CGROUP_DATA
#if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
DEFINE_SPINLOCK(cgroup_sk_update_lock);
sock, cgroup: add sock->sk_cgroup In cgroup v1, dealing with cgroup membership was difficult because the number of membership associations was unbound. As a result, cgroup v1 grew several controllers whose primary purpose is either tagging membership or pull in configuration knobs from other subsystems so that cgroup membership test can be avoided. net_cls and net_prio controllers are examples of the latter. They allow configuring network-specific attributes from cgroup side so that network subsystem can avoid testing cgroup membership; unfortunately, these are not only cumbersome but also problematic. Both net_cls and net_prio aren't properly hierarchical. Both inherit configuration from the parent on creation but there's no interaction afterwards. An ancestor doesn't restrict the behavior in its subtree in anyway and configuration changes aren't propagated downwards. Especially when combined with cgroup delegation, this is problematic because delegatees can mess up whatever network configuration implemented at the system level. net_prio would allow the delegatees to set whatever priority value regardless of CAP_NET_ADMIN and net_cls the same for classid. While it is possible to solve these issues from controller side by implementing hierarchical allowable ranges in both controllers, it would involve quite a bit of complexity in the controllers and further obfuscate network configuration as it becomes even more difficult to tell what's actually being configured looking from the network side. While not much can be done for v1 at this point, as membership handling is sane on cgroup v2, it'd be better to make cgroup matching behave like other network matches and classifiers than introducing further complications. In preparation, this patch updates sock->sk_cgrp_data handling so that it points to the v2 cgroup that sock was created in until either net_prio or net_cls is used. Once either of the two is used, sock->sk_cgrp_data reverts to its previous role of carrying prioidx and classid. This is to avoid adding yet another cgroup related field to struct sock. As the mode switching can happen at most once per boot, the switching mechanism is aimed at lowering hot path overhead. It may leak a finite, likely small, number of cgroup refs and report spurious prioidx or classid on switching; however, dynamic updates of prioidx and classid have always been racy and lossy - socks between creation and fd installation are never updated, config changes don't update existing sockets at all, and prioidx may index with dead and recycled cgroup IDs. Non-critical inaccuracies from small race windows won't make any noticeable difference. This patch doesn't make use of the pointer yet. The following patch will implement netfilter match for cgroup2 membership. v2: Use sock_cgroup_data to avoid inflating struct sock w/ another cgroup specific field. v3: Add comments explaining why sock_data_prioidx() and sock_data_classid() use different fallback values. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Daniel Wagner <daniel.wagner@bmw-carit.de> CC: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-08 01:38:53 +03:00
static bool cgroup_sk_alloc_disabled __read_mostly;
void cgroup_sk_alloc_disable(void)
{
if (cgroup_sk_alloc_disabled)
return;
pr_info("cgroup: disabling cgroup2 socket matching due to net_prio or net_cls activation\n");
cgroup_sk_alloc_disabled = true;
}
#else
#define cgroup_sk_alloc_disabled false
#endif
void cgroup_sk_alloc(struct sock_cgroup_data *skcd)
{
if (cgroup_sk_alloc_disabled)
return;
rcu_read_lock();
while (true) {
struct css_set *cset;
cset = task_css_set(current);
if (likely(cgroup_tryget(cset->dfl_cgrp))) {
skcd->val = (unsigned long)cset->dfl_cgrp;
break;
}
cpu_relax();
}
rcu_read_unlock();
}
void cgroup_sk_free(struct sock_cgroup_data *skcd)
{
cgroup_put(sock_cgroup_ptr(skcd));
}
#endif /* CONFIG_SOCK_CGROUP_DATA */
#ifdef CONFIG_CGROUP_DEBUG
cgroup: pass around cgroup_subsys_state instead of cgroup in subsystem methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup * in subsystem implementations for the following reasons. * With unified hierarchy, subsystems will be dynamically bound and unbound from cgroups and thus css's (cgroup_subsys_state) may be created and destroyed dynamically over the lifetime of a cgroup, which is different from the current state where all css's are allocated and destroyed together with the associated cgroup. This in turn means that cgroup_css() should be synchronized and may return NULL, making it more cumbersome to use. * Differing levels of per-subsystem granularity in the unified hierarchy means that the task and descendant iterators should behave differently depending on the specific subsystem the iteration is being performed for. * In majority of the cases, subsystems only care about its part in the cgroup hierarchy - ie. the hierarchy of css's. Subsystem methods often obtain the matching css pointer from the cgroup and don't bother with the cgroup pointer itself. Passing around css fits much better. This patch converts all cgroup_subsys methods to take @css instead of @cgroup. The conversions are mostly straight-forward. A few noteworthy changes are * ->css_alloc() now takes css of the parent cgroup rather than the pointer to the new cgroup as the css for the new cgroup doesn't exist yet. Knowing the parent css is enough for all the existing subsystems. * In kernel/cgroup.c::offline_css(), unnecessary open coded css dereference is replaced with local variable access. This patch shouldn't cause any behavior differences. v2: Unnecessary explicit cgrp->subsys[] deref in css_online() replaced with local variable @css as suggested by Li Zefan. Rebased on top of new for-3.12 which includes for-3.11-fixes so that ->css_free() invocation added by da0a12caff ("cgroup: fix a leak when percpu_ref_init() fails") is converted too. Suggested by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:23 +04:00
static struct cgroup_subsys_state *
debug_css_alloc(struct cgroup_subsys_state *parent_css)
{
struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
if (!css)
return ERR_PTR(-ENOMEM);
return css;
}
cgroup: pass around cgroup_subsys_state instead of cgroup in subsystem methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup * in subsystem implementations for the following reasons. * With unified hierarchy, subsystems will be dynamically bound and unbound from cgroups and thus css's (cgroup_subsys_state) may be created and destroyed dynamically over the lifetime of a cgroup, which is different from the current state where all css's are allocated and destroyed together with the associated cgroup. This in turn means that cgroup_css() should be synchronized and may return NULL, making it more cumbersome to use. * Differing levels of per-subsystem granularity in the unified hierarchy means that the task and descendant iterators should behave differently depending on the specific subsystem the iteration is being performed for. * In majority of the cases, subsystems only care about its part in the cgroup hierarchy - ie. the hierarchy of css's. Subsystem methods often obtain the matching css pointer from the cgroup and don't bother with the cgroup pointer itself. Passing around css fits much better. This patch converts all cgroup_subsys methods to take @css instead of @cgroup. The conversions are mostly straight-forward. A few noteworthy changes are * ->css_alloc() now takes css of the parent cgroup rather than the pointer to the new cgroup as the css for the new cgroup doesn't exist yet. Knowing the parent css is enough for all the existing subsystems. * In kernel/cgroup.c::offline_css(), unnecessary open coded css dereference is replaced with local variable access. This patch shouldn't cause any behavior differences. v2: Unnecessary explicit cgrp->subsys[] deref in css_online() replaced with local variable @css as suggested by Li Zefan. Rebased on top of new for-3.12 which includes for-3.11-fixes so that ->css_free() invocation added by da0a12caff ("cgroup: fix a leak when percpu_ref_init() fails") is converted too. Suggested by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:23 +04:00
static void debug_css_free(struct cgroup_subsys_state *css)
{
cgroup: pass around cgroup_subsys_state instead of cgroup in subsystem methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup * in subsystem implementations for the following reasons. * With unified hierarchy, subsystems will be dynamically bound and unbound from cgroups and thus css's (cgroup_subsys_state) may be created and destroyed dynamically over the lifetime of a cgroup, which is different from the current state where all css's are allocated and destroyed together with the associated cgroup. This in turn means that cgroup_css() should be synchronized and may return NULL, making it more cumbersome to use. * Differing levels of per-subsystem granularity in the unified hierarchy means that the task and descendant iterators should behave differently depending on the specific subsystem the iteration is being performed for. * In majority of the cases, subsystems only care about its part in the cgroup hierarchy - ie. the hierarchy of css's. Subsystem methods often obtain the matching css pointer from the cgroup and don't bother with the cgroup pointer itself. Passing around css fits much better. This patch converts all cgroup_subsys methods to take @css instead of @cgroup. The conversions are mostly straight-forward. A few noteworthy changes are * ->css_alloc() now takes css of the parent cgroup rather than the pointer to the new cgroup as the css for the new cgroup doesn't exist yet. Knowing the parent css is enough for all the existing subsystems. * In kernel/cgroup.c::offline_css(), unnecessary open coded css dereference is replaced with local variable access. This patch shouldn't cause any behavior differences. v2: Unnecessary explicit cgrp->subsys[] deref in css_online() replaced with local variable @css as suggested by Li Zefan. Rebased on top of new for-3.12 which includes for-3.11-fixes so that ->css_free() invocation added by da0a12caff ("cgroup: fix a leak when percpu_ref_init() fails") is converted too. Suggested by Li Zefan. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:23 +04:00
kfree(css);
}
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
return cgroup_task_count(css->cgroup);
}
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
static u64 current_css_set_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
return (u64)(unsigned long)current->cgroups;
}
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
struct cftype *cft)
{
u64 count;
rcu_read_lock();
count = atomic_read(&task_css_set(current)->refcount);
rcu_read_unlock();
return count;
}
static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
{
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
struct cgrp_cset_link *link;
struct css_set *cset;
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
char *name_buf;
name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
if (!name_buf)
return -ENOMEM;
spin_lock_bh(&css_set_lock);
rcu_read_lock();
cset = rcu_dereference(current->cgroups);
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
struct cgroup *c = link->cgrp;
2014-03-19 18:23:55 +04:00
cgroup_name(c, name_buf, NAME_MAX + 1);
seq_printf(seq, "Root %d group %s\n",
2014-03-19 18:23:55 +04:00
c->root->hierarchy_id, name_buf);
}
rcu_read_unlock();
spin_unlock_bh(&css_set_lock);
cgroup: remove cgroup->name cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
2014-02-12 18:29:50 +04:00
kfree(name_buf);
return 0;
}
#define MAX_TASKS_SHOWN_PER_CSS 25
static int cgroup_css_links_read(struct seq_file *seq, void *v)
{
struct cgroup_subsys_state *css = seq_css(seq);
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
struct cgrp_cset_link *link;
spin_lock_bh(&css_set_lock);
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
cgroup: bring some sanity to naming around cg_cgroup_link cgroups and css_sets are mapped M:N and this M:N mapping is represented by struct cg_cgroup_link which forms linked lists on both sides. The naming around this mapping is already confusing and struct cg_cgroup_link exacerbates the situation quite a bit. >From cgroup side, it starts off ->css_sets and runs through ->cgrp_link_list. From css_set side, it starts off ->cg_links and runs through ->cg_link_list. This is rather reversed as cgrp_link_list is used to iterate css_sets and cg_link_list cgroups. Also, this is the only place which is still using the confusing "cg" for css_sets. This patch cleans it up a bit. * s/cgroup->css_sets/cgroup->cset_links/ s/css_set->cg_links/css_set->cgrp_links/ s/cgroup_iter->cg_link/cgroup_iter->cset_link/ * s/cg_cgroup_link/cgrp_cset_link/ * s/cgrp_cset_link->cg/cgrp_cset_link->cset/ s/cgrp_cset_link->cgrp_link_list/cgrp_cset_link->cset_link/ s/cgrp_cset_link->cg_link_list/cgrp_cset_link->cgrp_link/ * s/init_css_set_link/init_cgrp_cset_link/ s/free_cg_links/free_cgrp_cset_links/ s/allocate_cg_links/allocate_cgrp_cset_links/ * s/cgl[12]/link[12]/ in compare_css_sets() * s/saved_link/tmp_link/ s/tmp/tmp_links/ and a couple similar adustments. * Comment and whiteline adjustments. After the changes, we have list_for_each_entry(link, &cont->cset_links, cset_link) { struct css_set *cset = link->cset; instead of list_for_each_entry(link, &cont->css_sets, cgrp_link_list) { struct css_set *cset = link->cg; This patch is purely cosmetic. v2: Fix broken sentences in the patch description. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2013-06-13 08:04:50 +04:00
struct css_set *cset = link->cset;
struct task_struct *task;
int count = 0;
cgroup: add css_set->mg_tasks Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, we're going to use task->cg_list during migration too. Instead of building a separate array, target tasks will be linked into a dedicated migration list_head on the owning css_set. Tasks on the migration list are treated the same as tasks on the usual tasks list; however, being on a separate list allows cgroup migration code path to keep track of the target tasks by simply keeping the list of css_sets with tasks being migrated, making unpredictable dynamic allocation unnecessary. In prepartion of such migration path update, this patch introduces css_set->mg_tasks list and updates css_set task iterations so that they walk both css_set->tasks and ->mg_tasks. Note that ->mg_tasks isn't used yet. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
seq_printf(seq, "css_set %p\n", cset);
cgroup: add css_set->mg_tasks Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, we're going to use task->cg_list during migration too. Instead of building a separate array, target tasks will be linked into a dedicated migration list_head on the owning css_set. Tasks on the migration list are treated the same as tasks on the usual tasks list; however, being on a separate list allows cgroup migration code path to keep track of the target tasks by simply keeping the list of css_sets with tasks being migrated, making unpredictable dynamic allocation unnecessary. In prepartion of such migration path update, this patch introduces css_set->mg_tasks list and updates css_set task iterations so that they walk both css_set->tasks and ->mg_tasks. Note that ->mg_tasks isn't used yet. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
list_for_each_entry(task, &cset->tasks, cg_list) {
cgroup: add css_set->mg_tasks Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, we're going to use task->cg_list during migration too. Instead of building a separate array, target tasks will be linked into a dedicated migration list_head on the owning css_set. Tasks on the migration list are treated the same as tasks on the usual tasks list; however, being on a separate list allows cgroup migration code path to keep track of the target tasks by simply keeping the list of css_sets with tasks being migrated, making unpredictable dynamic allocation unnecessary. In prepartion of such migration path update, this patch introduces css_set->mg_tasks list and updates css_set task iterations so that they walk both css_set->tasks and ->mg_tasks. Note that ->mg_tasks isn't used yet. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
if (count++ > MAX_TASKS_SHOWN_PER_CSS)
goto overflow;
seq_printf(seq, " task %d\n", task_pid_vnr(task));
}
list_for_each_entry(task, &cset->mg_tasks, cg_list) {
if (count++ > MAX_TASKS_SHOWN_PER_CSS)
goto overflow;
seq_printf(seq, " task %d\n", task_pid_vnr(task));
}
cgroup: add css_set->mg_tasks Currently, while migrating tasks from one cgroup to another, cgroup_attach_task() builds a flex array of all target tasks; unfortunately, this has a couple issues. * Flex array has size limit. On 64bit, struct task_and_cgroup is 24bytes making the flex element limit around 87k. It is a high number but not impossible to hit. This means that the current cgroup implementation can't migrate a process with more than 87k threads. * Process migration involves memory allocation whose size is dependent on the number of threads the process has. This means that cgroup core can't guarantee success or failure of multi-process migrations as memory allocation failure can happen in the middle. This is in part because cgroup can't grab threadgroup locks of multiple processes at the same time, so when there are multiple processes to migrate, it is imposible to tell how many tasks are to be migrated beforehand. Note that this already affects cgroup_transfer_tasks(). cgroup currently cannot guarantee atomic success or failure of the operation. It may fail in the middle and after such failure cgroup doesn't have enough information to roll back properly. It just aborts with some tasks migrated and others not. To resolve the situation, we're going to use task->cg_list during migration too. Instead of building a separate array, target tasks will be linked into a dedicated migration list_head on the owning css_set. Tasks on the migration list are treated the same as tasks on the usual tasks list; however, being on a separate list allows cgroup migration code path to keep track of the target tasks by simply keeping the list of css_sets with tasks being migrated, making unpredictable dynamic allocation unnecessary. In prepartion of such migration path update, this patch introduces css_set->mg_tasks list and updates css_set task iterations so that they walk both css_set->tasks and ->mg_tasks. Note that ->mg_tasks isn't used yet. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
2014-02-25 19:04:01 +04:00
continue;
overflow:
seq_puts(seq, " ...\n");
}
spin_unlock_bh(&css_set_lock);
return 0;
}
cgroup: pass around cgroup_subsys_state instead of cgroup in file methods cgroup is currently in the process of transitioning to using struct cgroup_subsys_state * as the primary handle instead of struct cgroup. Please see the previous commit which converts the subsystem methods for rationale. This patch converts all cftype file operations to take @css instead of @cgroup. cftypes for the cgroup core files don't have their subsytem pointer set. These will automatically use the dummy_css added by the previous patch and can be converted the same way. Most subsystem conversions are straight forwards but there are some interesting ones. * freezer: update_if_frozen() is also converted to take @css instead of @cgroup for consistency. This will make the code look simpler too once iterators are converted to use css. * memory/vmpressure: mem_cgroup_from_css() needs to be exported to vmpressure while mem_cgroup_from_cont() can be made static. Updated accordingly. * cpu: cgroup_tg() doesn't have any user left. Removed. * cpuacct: cgroup_ca() doesn't have any user left. Removed. * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left. Removed. * net_cls: cgrp_cls_state() doesn't have any user left. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-09 04:11:24 +04:00
static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
{
return (!cgroup_is_populated(css->cgroup) &&
!css_has_online_children(&css->cgroup->self));
}
static struct cftype debug_files[] = {
{
.name = "taskcount",
.read_u64 = debug_taskcount_read,
},
{
.name = "current_css_set",
.read_u64 = current_css_set_read,
},
{
.name = "current_css_set_refcount",
.read_u64 = current_css_set_refcount_read,
},
{
.name = "current_css_set_cg_links",
.seq_show = current_css_set_cg_links_read,
},
{
.name = "cgroup_css_links",
.seq_show = cgroup_css_links_read,
},
{
.name = "releasable",
.read_u64 = releasable_read,
},
{ } /* terminate */
};
cgroup: clean up cgroup_subsys names and initialization cgroup_subsys is a bit messier than it needs to be. * The name of a subsys can be different from its internal identifier defined in cgroup_subsys.h. Most subsystems use the matching name but three - cpu, memory and perf_event - use different ones. * cgroup_subsys_id enums are postfixed with _subsys_id and each cgroup_subsys is postfixed with _subsys. cgroup.h is widely included throughout various subsystems, it doesn't and shouldn't have claim on such generic names which don't have any qualifier indicating that they belong to cgroup. * cgroup_subsys->subsys_id should always equal the matching cgroup_subsys_id enum; however, we require each controller to initialize it and then BUG if they don't match, which is a bit silly. This patch cleans up cgroup_subsys names and initialization by doing the followings. * cgroup_subsys_id enums are now postfixed with _cgrp_id, and each cgroup_subsys with _cgrp_subsys. * With the above, renaming subsys identifiers to match the userland visible names doesn't cause any naming conflicts. All non-matching identifiers are renamed to match the official names. cpu_cgroup -> cpu mem_cgroup -> memory perf -> perf_event * controllers no longer need to initialize ->subsys_id and ->name. They're generated in cgroup core and set automatically during boot. * Redundant cgroup_subsys declarations removed. * While updating BUG_ON()s in cgroup_init_early(), convert them to WARN()s. BUGging that early during boot is stupid - the kernel can't print anything, even through serial console and the trap handler doesn't even link stack frame properly for back-tracing. This patch doesn't introduce any behavior changes. v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs classid handling into core"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: "David S. Miller" <davem@davemloft.net> Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Ingo Molnar <mingo@redhat.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Thomas Graf <tgraf@suug.ch>
2014-02-08 19:36:58 +04:00
struct cgroup_subsys debug_cgrp_subsys = {
.css_alloc = debug_css_alloc,
.css_free = debug_css_free,
.legacy_cftypes = debug_files,
};
#endif /* CONFIG_CGROUP_DEBUG */