e7fd37ba12 ("cgroup: avoid copying strings longer than the buffers")
converted possibly unsafe strncpy() usages in cgroup to strscpy().
However, although the callsites are completely fine with truncated
copied, because strscpy() is marked __must_check, it led to the
following warnings.
kernel/cgroup/cgroup.c: In function ‘cgroup_file_name’:
kernel/cgroup/cgroup.c:1400:10: warning: ignoring return value of ‘strscpy’, declared with attribute warn_unused_result [-Wunused-result]
strscpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
^
To avoid the warnings, 50034ed496 ("cgroup: use strlcpy() instead of
strscpy() to avoid spurious warning") switched them to strlcpy().
strlcpy() is worse than strlcpy() because it unconditionally runs
strlen() on the source string, and the only reason we switched to
strlcpy() here was because it was lacking __must_check, which doesn't
reflect any material differences between the two function. It's just
that someone added __must_check to strscpy() and not to strlcpy().
These basic string copy operations are used in variety of ways, and
one of not-so-uncommon use cases is safely handling truncated copies,
where the caller naturally doesn't care about the return value. The
__must_check doesn't match the actual use cases and forces users to
opt for inferior variants which lack __must_check by happenstance or
spread ugly (void) casts.
Remove __must_check from strscpy() and restore strscpy() usages in
cgroup.
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ma Shimiao <mashimiao.fnst@cn.fujitsu.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Make cgroup.threads file delegatable.
The behavior of cgroup.threads should follow the behavior of cgroup.procs.
Signed-off-by: Roman Gushchin <guro@fb.com>
Discovered-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
As long as cft->name is guaranteed to be NUL-terminated, using strlcpy() would
work just as well and avoid that warning, so the change below could be folded
into that commit.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Tejun Heo <tj@kernel.org>
cgroup root name and file name have max length limit, we should
avoid copying longer name than that to the name.
tj: minor update to $SUBJ.
Signed-off-by: Ma Shimiao <mashimiao.fnst@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull cgroup updates from Tejun Heo:
"Cgroup2 cpu controller support is finally merged.
- Basic cpu statistics support to allow monitoring by default without
the CPU controller enabled.
- cgroup2 cpu controller support.
- /sys/kernel/cgroup files to help dealing with new / optional
features"
* 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: export list of cgroups v2 features using sysfs
cgroup: export list of delegatable control files using sysfs
cgroup: mark @cgrp __maybe_unused in cpu_stat_show()
MAINTAINERS: relocate cpuset.c
cgroup, sched: Move basic cpu stats from cgroup.stat to cpu.stat
sched: Implement interface for cgroup unified hierarchy
sched: Misc preps for cgroup unified hierarchy interface
sched/cputime: Add dummy cputime_adjust() implementation for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
cgroup: statically initialize init_css_set->dfl_cgrp
cgroup: Implement cgroup2 basic CPU usage accounting
cpuacct: Introduce cgroup_account_cputime[_field]()
sched/cputime: Expose cputime_adjust()
The active development of cgroups v2 sometimes leads to a creation
of interfaces, which are not turned on by default (to provide
backward compatibility). It's handy to know from userspace, which
cgroup v2 features are supported without calculating it based
on the kernel version. So, let's export the list of such features
using /sys/kernel/cgroup/features pseudo-file.
The list is hardcoded and has to be extended when new functionality
is added. Each feature is printed on a new line.
Example:
$ cat /sys/kernel/cgroup/features
nsdelegate
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: kernel-team@fb.com
Signed-off-by: Tejun Heo <tj@kernel.org>
Delegatable cgroup v2 control files may require special handling
(e.g. chowning), and the exact list of such files varies between
kernel versions (and likely to be extended in the future).
To guarantee correctness of this list and simplify the life
of userspace (systemd, first of all), let's export the list
via /sys/kernel/cgroup/delegate pseudo-file.
Format is siple: each control file name is printed on a new line.
Example:
$ cat /sys/kernel/cgroup/delegate
cgroup.procs
cgroup.subtree_control
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: kernel-team@fb.com
Signed-off-by: Tejun Heo <tj@kernel.org>
The local variable @cgrp isn't used if !CONFIG_CGROUP_SCHED. Mark the
variable with __maybe_unused to avoid a compile warning.
Reported-by: "kbuild-all@01.org" <kbuild-all@01.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
The basic cpu stat is currently shown with "cpu." prefix in
cgroup.stat, and the same information is duplicated in cpu.stat when
cpu controller is enabled. This is ugly and not very scalable as we
want to expand the coverage of stat information which is always
available.
This patch makes cgroup core always create "cpu.stat" file and show
the basic cpu stat there and calls the cpu controller to show the
extra stats when enabled. This ensures that the same information
isn't presented in multiple places and makes future expansion of basic
stats easier.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
introduce BPF_PROG_QUERY command to retrieve a set of either
attached programs to given cgroup or a set of effective programs
that will execute for events within a cgroup
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
for cgroup bits
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
introduce BPF_F_ALLOW_MULTI flag that can be used to attach multiple
bpf programs to a cgroup.
The difference between three possible flags for BPF_PROG_ATTACH command:
- NONE(default): No further bpf programs allowed in the subtree.
- BPF_F_ALLOW_OVERRIDE: If a sub-cgroup installs some bpf program,
the program in this cgroup yields to sub-cgroup program.
- BPF_F_ALLOW_MULTI: If a sub-cgroup installs some bpf program,
that cgroup program gets run in addition to the program in this cgroup.
NONE and BPF_F_ALLOW_OVERRIDE existed before. This patch doesn't
change their behavior. It only clarifies the semantics in relation
to new flag.
Only one program is allowed to be attached to a cgroup with
NONE or BPF_F_ALLOW_OVERRIDE flag.
Multiple programs are allowed to be attached to a cgroup with
BPF_F_ALLOW_MULTI flag. They are executed in FIFO order
(those that were attached first, run first)
The programs of sub-cgroup are executed first, then programs of
this cgroup and then programs of parent cgroup.
All eligible programs are executed regardless of return code from
earlier programs.
To allow efficient execution of multiple programs attached to a cgroup
and to avoid penalizing cgroups without any programs attached
introduce 'struct bpf_prog_array' which is RCU protected array
of pointers to bpf programs.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
for cgroup bits
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
In cgroup1, while cpuacct isn't actually controlling any resources, it
is a separate controller due to combination of two factors -
1. enabling cpu controller has significant side effects, and 2. we
have to pick one of the hierarchies to account CPU usages on. cpuacct
controller is effectively used to designate a hierarchy to track CPU
usages on.
cgroup2's unified hierarchy removes the second reason and we can
account basic CPU usages by default. While we can use cpuacct for
this purpose, both its interface and implementation leave a lot to be
desired - it collects and exposes two sources of truth which don't
agree with each other and some of the exposed statistics don't make
much sense. Also, it propagates all the way up the hierarchy on each
accounting event which is unnecessary.
This patch adds basic resource accounting mechanism to cgroup2's
unified hierarchy and accounts CPU usages using it.
* All accountings are done per-cpu and don't propagate immediately.
It just bumps the per-cgroup per-cpu counters and links to the
parent's updated list if not already on it.
* On a read, the per-cpu counters are collected into the global ones
and then propagated upwards. Only the per-cpu counters which have
changed since the last read are propagated.
* CPU usage stats are collected and shown in "cgroup.stat" with "cpu."
prefix. Total usage is collected from scheduling events. User/sys
breakdown is sourced from tick sampling and adjusted to the usage
using cputime_adjust().
This keeps the accounting side hot path O(1) and per-cpu and the read
side O(nr_updated_since_last_read).
v2: Minor changes and documentation updates as suggested by Waiman and
Roman.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Roman Gushchin <guro@fb.com>
The cgroup_taskset structure within the larger cgroup_mgctx structure
is supposed to be used once and then discarded. That is not really the
case in the hotplug code path:
cpuset_hotplug_workfn()
- cgroup_transfer_tasks()
- cgroup_migrate()
- cgroup_migrate_add_task()
- cgroup_migrate_execute()
In this case, the cgroup_migrate() function is called multiple time
with the same cgroup_mgctx structure to transfer the tasks from
one cgroup to another one-by-one. The second time cgroup_migrate()
is called, the cgroup_taskset will be in an incorrect state and so
may cause the system to panic. For example,
[ 150.888410] Faulting instruction address: 0xc0000000001db648
[ 150.888414] Oops: Kernel access of bad area, sig: 11 [#1]
[ 150.888417] SMP NR_CPUS=2048
[ 150.888417] NUMA
[ 150.888419] pSeries
:
[ 150.888545] NIP [c0000000001db648] cpuset_can_attach+0x58/0x1b0
[ 150.888548] LR [c0000000001db638] cpuset_can_attach+0x48/0x1b0
[ 150.888551] Call Trace:
[ 150.888554] [c0000005f65cb940] [c0000000001db638] cpuset_can_attach+0x48/0x1b 0 (unreliable)
[ 150.888559] [c0000005f65cb9a0] [c0000000001cff04] cgroup_migrate_execute+0xc4/0x4b0
[ 150.888563] [c0000005f65cba20] [c0000000001d7d14] cgroup_transfer_tasks+0x1d4/0x370
[ 150.888568] [c0000005f65cbb70] [c0000000001ddcb0] cpuset_hotplug_workfn+0x710/0x8f0
[ 150.888572] [c0000005f65cbc80] [c00000000012032c] process_one_work+0x1ac/0x4d0
[ 150.888576] [c0000005f65cbd20] [c0000000001206f8] worker_thread+0xa8/0x5b0
[ 150.888580] [c0000005f65cbdc0] [c0000000001293f8] kthread+0x168/0x1b0
[ 150.888584] [c0000005f65cbe30] [c00000000000b368] ret_from_kernel_thread+0x5c/0x74
To allow reuse of the cgroup_mgctx structure, some fields in that
structure are now re-initialized at the end of cgroup_migrate_execute()
function call so that the structure can be reused again in a later
iteration without causing problem.
This bug was introduced in the commit e595cd7069 ("group: track
migration context in cgroup_mgctx") in 4.11. This commit moves the
cgroup_taskset initialization out of cgroup_migrate(). The commit
10467270fb3 ("cgroup: don't call migration methods if there are no
tasks to migrate") helped, but did not completely resolve the problem.
Fixes: e595cd7069 ("group: track migration context in cgroup_mgctx")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # v4.11+
Pull block layer updates from Jens Axboe:
"This is the first pull request for 4.14, containing most of the code
changes. It's a quiet series this round, which I think we needed after
the churn of the last few series. This contains:
- Fix for a registration race in loop, from Anton Volkov.
- Overflow complaint fix from Arnd for DAC960.
- Series of drbd changes from the usual suspects.
- Conversion of the stec/skd driver to blk-mq. From Bart.
- A few BFQ improvements/fixes from Paolo.
- CFQ improvement from Ritesh, allowing idling for group idle.
- A few fixes found by Dan's smatch, courtesy of Dan.
- A warning fixup for a race between changing the IO scheduler and
device remova. From David Jeffery.
- A few nbd fixes from Josef.
- Support for cgroup info in blktrace, from Shaohua.
- Also from Shaohua, new features in the null_blk driver to allow it
to actually hold data, among other things.
- Various corner cases and error handling fixes from Weiping Zhang.
- Improvements to the IO stats tracking for blk-mq from me. Can
drastically improve performance for fast devices and/or big
machines.
- Series from Christoph removing bi_bdev as being needed for IO
submission, in preparation for nvme multipathing code.
- Series from Bart, including various cleanups and fixes for switch
fall through case complaints"
* 'for-4.14/block' of git://git.kernel.dk/linux-block: (162 commits)
kernfs: checking for IS_ERR() instead of NULL
drbd: remove BIOSET_NEED_RESCUER flag from drbd_{md_,}io_bio_set
drbd: Fix allyesconfig build, fix recent commit
drbd: switch from kmalloc() to kmalloc_array()
drbd: abort drbd_start_resync if there is no connection
drbd: move global variables to drbd namespace and make some static
drbd: rename "usermode_helper" to "drbd_usermode_helper"
drbd: fix race between handshake and admin disconnect/down
drbd: fix potential deadlock when trying to detach during handshake
drbd: A single dot should be put into a sequence.
drbd: fix rmmod cleanup, remove _all_ debugfs entries
drbd: Use setup_timer() instead of init_timer() to simplify the code.
drbd: fix potential get_ldev/put_ldev refcount imbalance during attach
drbd: new disk-option disable-write-same
drbd: Fix resource role for newly created resources in events2
drbd: mark symbols static where possible
drbd: Send P_NEG_ACK upon write error in protocol != C
drbd: add explicit plugging when submitting batches
drbd: change list_for_each_safe to while(list_first_entry_or_null)
drbd: introduce drbd_recv_header_maybe_unplug
...
Pull cgroup updates from Tejun Heo:
"Several notable changes this cycle:
- Thread mode was merged. This will be used for cgroup2 support for
CPU and possibly other controllers. Unfortunately, CPU controller
cgroup2 support didn't make this pull request but most contentions
have been resolved and the support is likely to be merged before
the next merge window.
- cgroup.stat now shows the number of descendant cgroups.
- cpuset now can enable the easier-to-configure v2 behavior on v1
hierarchy"
* 'for-4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (21 commits)
cpuset: Allow v2 behavior in v1 cgroup
cgroup: Add mount flag to enable cpuset to use v2 behavior in v1 cgroup
cgroup: remove unneeded checks
cgroup: misc changes
cgroup: short-circuit cset_cgroup_from_root() on the default hierarchy
cgroup: re-use the parent pointer in cgroup_destroy_locked()
cgroup: add cgroup.stat interface with basic hierarchy stats
cgroup: implement hierarchy limits
cgroup: keep track of number of descent cgroups
cgroup: add comment to cgroup_enable_threaded()
cgroup: remove unnecessary empty check when enabling threaded mode
cgroup: update debug controller to print out thread mode information
cgroup: implement cgroup v2 thread support
cgroup: implement CSS_TASK_ITER_THREADED
cgroup: introduce cgroup->dom_cgrp and threaded css_set handling
cgroup: add @flags to css_task_iter_start() and implement CSS_TASK_ITER_PROCS
cgroup: reorganize cgroup.procs / task write path
cgroup: replace css_set walking populated test with testing cgrp->nr_populated_csets
cgroup: distinguish local and children populated states
cgroup: remove now unused list_head @pending in cgroup_apply_cftypes()
...
Commit fa06235b8e ("cgroup: reset css on destruction") caused
css_reset callback to be called from the offlining path. Although it
solves the problem mentioned in the commit description ("For instance,
memory cgroup needs to reset memory.low, otherwise pages charged to a
dead cgroup might never get reclaimed."), generally speaking, it's not
correct.
An offline cgroup can still be a resource domain, and we shouldn't grant
it more resources than it had before deletion.
For instance, if an offline memory cgroup has dirty pages, we should
still imply i/o limits during writeback.
The css_reset callback is designed to return the cgroup state into the
original state, that means reset all limits and counters. It's
spomething different from the offlining, and we shouldn't use it from
the offlining path. Instead, we should adjust necessary settings from
the per-controller css_offline callbacks (e.g. reset memory.low).
Link: http://lkml.kernel.org/r/20170727130428.28856-2-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
"descendants" and "depth" are declared as int, so they can't be larger
than INT_MAX. Static checkers complain and it's slightly confusing for
humans as well so let's just remove these conditions.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Misc trivial changes to prepare for future changes. No functional
difference.
* Expose cgroup_get(), cgroup_tryget() and cgroup_parent().
* Implement task_dfl_cgroup() which dereferences css_set->dfl_cgrp.
* Rename cgroup_stats_show() to cgroup_stat_show() for consistency
with the file name.
Signed-off-by: Tejun Heo <tj@kernel.org>
Each css_set directly points to the default cgroup it belongs to, so
there's no reason to walk the cgrp_links list on the default
hierarchy.
Signed-off-by: Tejun Heo <tj@kernel.org>
As we already have a pointer to the parent cgroup in
cgroup_destroy_locked(), we don't need to calculate it again
to pass as an argument for cgroup1_check_for_release().
Signed-off-by: Roman Gushchin <guro@fb.com>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: kernel-team@fb.com
Cc: linux-kernel@vger.kernel.org
A cgroup can consume resources even after being deleted by a user.
For example, writing back dirty pages should be accounted and
limited, despite the corresponding cgroup might contain no processes
and being deleted by a user.
In the current implementation a cgroup can remain in such "dying" state
for an undefined amount of time. For instance, if a memory cgroup
contains a pge, mlocked by a process belonging to an other cgroup.
Although the lifecycle of a dying cgroup is out of user's control,
it's important to have some insight of what's going on under the hood.
In particular, it's handy to have a counter which will allow
to detect css leaks.
To solve this problem, add a cgroup.stat interface to
the base cgroup control files with the following metrics:
nr_descendants total number of visible descendant cgroups
nr_dying_descendants total number of dying descendant cgroups
Signed-off-by: Roman Gushchin <guro@fb.com>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: kernel-team@fb.com
Cc: cgroups@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Creating cgroup hierearchies of unreasonable size can affect
overall system performance. A user might want to limit the
size of cgroup hierarchy. This is especially important if a user
is delegating some cgroup sub-tree.
To address this issue, introduce an ability to control
the size of cgroup hierarchy.
The cgroup.max.descendants control file allows to set the maximum
allowed number of descendant cgroups.
The cgroup.max.depth file controls the maximum depth of the cgroup
tree. Both are single value r/w files, with "max" default value.
The control files exist on each hierarchy level (including root).
When a new cgroup is created, we check the total descendants
and depth limits on each level, and if none of them are exceeded,
a new cgroup is created.
Only alive cgroups are counted, removed (dying) cgroups are
ignored.
Signed-off-by: Roman Gushchin <guro@fb.com>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: kernel-team@fb.com
Cc: cgroups@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Keep track of the number of online and dying descent cgroups.
This data will be used later to add an ability to control cgroup
hierarchy (limit the depth and the number of descent cgroups)
and display hierarchy stats.
Signed-off-by: Roman Gushchin <guro@fb.com>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: kernel-team@fb.com
Cc: cgroups@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
By default we output cgroup id in blktrace. This adds an option to
display cgroup path. Since get cgroup path is a relativly heavy
operation, we don't enable it by default.
with the option enabled, blktrace will output something like this:
dd-1353 [007] d..2 293.015252: 8,0 /test/level D R 24 + 8 [dd]
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Now we have the facilities to implement exportfs operations. The idea is
cgroup can export the fhandle info to userspace, then userspace uses
fhandle to find the cgroup name. Another example is userspace can get
fhandle for a cgroup and BPF uses the fhandle to filter info for the
cgroup.
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Explain cgroup_enable_threaded() and note that the function can never
be called on the root cgroup.
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Waiman Long <longman@redhat.com>
cgroup_enable_threaded() checks that the cgroup doesn't have any tasks
or children and fails the operation if so. This test is unnecessary
because the first part is already checked by
cgroup_can_be_thread_root() and the latter is unnecessary. The latter
actually cause a behavioral oddity. Please consider the following
hierarchy. All cgroups are domains.
A
/ \
B C
\
D
If B is made threaded, C and D becomes invalid domains. Due to the no
children restriction, threaded mode can't be enabled on C. For C and
D, the only thing the user can do is removal.
There is no reason for this restriction. Remove it.
Acked-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
While refactoring, f7b2814bb9 ("cgroup: factor out
cgroup_{apply|finalize}_control() from
cgroup_subtree_control_write()") broke error return value from the
function. The return value from the last operation is always
overridden to zero. Fix it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # v4.6+
Signed-off-by: Tejun Heo <tj@kernel.org>
Update debug controller so that it prints out debug info about thread
mode.
1) The relationship between proc_cset and threaded_csets are displayed.
2) The status of being a thread root or threaded cgroup is displayed.
This patch is extracted from Waiman's larger patch.
v2: - Removed [thread root] / [threaded] from debug.cgroup_css_links
file as the same information is available from cgroup.type.
Suggested by Waiman.
- Threaded marking is moved to the previous patch.
Patch-originally-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This patch implements cgroup v2 thread support. The goal of the
thread mode is supporting hierarchical accounting and control at
thread granularity while staying inside the resource domain model
which allows coordination across different resource controllers and
handling of anonymous resource consumptions.
A cgroup is always created as a domain and can be made threaded by
writing to the "cgroup.type" file. When a cgroup becomes threaded, it
becomes a member of a threaded subtree which is anchored at the
closest ancestor which isn't threaded.
The threads of the processes which are in a threaded subtree can be
placed anywhere without being restricted by process granularity or
no-internal-process constraint. Note that the threads aren't allowed
to escape to a different threaded subtree. To be used inside a
threaded subtree, a controller should explicitly support threaded mode
and be able to handle internal competition in the way which is
appropriate for the resource.
The root of a threaded subtree, the nearest ancestor which isn't
threaded, is called the threaded domain and serves as the resource
domain for the whole subtree. This is the last cgroup where domain
controllers are operational and where all the domain-level resource
consumptions in the subtree are accounted. This allows threaded
controllers to operate at thread granularity when requested while
staying inside the scope of system-level resource distribution.
As the root cgroup is exempt from the no-internal-process constraint,
it can serve as both a threaded domain and a parent to normal cgroups,
so, unlike non-root cgroups, the root cgroup can have both domain and
threaded children.
Internally, in a threaded subtree, each css_set has its ->dom_cset
pointing to a matching css_set which belongs to the threaded domain.
This ensures that thread root level cgroup_subsys_state for all
threaded controllers are readily accessible for domain-level
operations.
This patch enables threaded mode for the pids and perf_events
controllers. Neither has to worry about domain-level resource
consumptions and it's enough to simply set the flag.
For more details on the interface and behavior of the thread mode,
please refer to the section 2-2-2 in Documentation/cgroup-v2.txt added
by this patch.
v5: - Dropped silly no-op ->dom_cgrp init from cgroup_create().
Spotted by Waiman.
- Documentation updated as suggested by Waiman.
- cgroup.type content slightly reformatted.
- Mark the debug controller threaded.
v4: - Updated to the general idea of marking specific cgroups
domain/threaded as suggested by PeterZ.
v3: - Dropped "join" and always make mixed children join the parent's
threaded subtree.
v2: - After discussions with Waiman, support for mixed thread mode is
added. This should address the issue that Peter pointed out
where any nesting should be avoided for thread subtrees while
coexisting with other domain cgroups.
- Enabling / disabling thread mode now piggy backs on the existing
control mask update mechanism.
- Bug fixes and cleanup.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
cgroup v2 is in the process of growing thread granularity support.
Once thread mode is enabled, the root cgroup of the subtree serves as
the dom_cgrp to which the processes of the subtree conceptually belong
and domain-level resource consumptions not tied to any specific task
are charged. In the subtree, threads won't be subject to process
granularity or no-internal-task constraint and can be distributed
arbitrarily across the subtree.
This patch implements a new task iterator flag CSS_TASK_ITER_THREADED,
which, when used on a dom_cgrp, makes the iteration include the tasks
on all the associated threaded css_sets. "cgroup.procs" read path is
updated to use it so that reading the file on a proc_cgrp lists all
processes. This will also be used by controller implementations which
need to walk processes or tasks at the resource domain level.
Task iteration is implemented nested in css_set iteration. If
CSS_TASK_ITER_THREADED is specified, after walking tasks of each
!threaded css_set, all the associated threaded css_sets are visited
before moving onto the next !threaded css_set.
v2: ->cur_pcset renamed to ->cur_dcset. Updated for the new
enable-threaded-per-cgroup behavior.
Signed-off-by: Tejun Heo <tj@kernel.org>
cgroup v2 is in the process of growing thread granularity support. A
threaded subtree is composed of a thread root and threaded cgroups
which are proper members of the subtree.
The root cgroup of the subtree serves as the domain cgroup to which
the processes (as opposed to threads / tasks) of the subtree
conceptually belong and domain-level resource consumptions not tied to
any specific task are charged. Inside the subtree, threads won't be
subject to process granularity or no-internal-task constraint and can
be distributed arbitrarily across the subtree.
This patch introduces cgroup->dom_cgrp along with threaded css_set
handling.
* cgroup->dom_cgrp points to self for normal and thread roots. For
proper thread subtree members, points to the dom_cgrp (the thread
root).
* css_set->dom_cset points to self if for normal and thread roots. If
threaded, points to the css_set which belongs to the cgrp->dom_cgrp.
The dom_cgrp serves as the resource domain and keeps the matching
csses available. The dom_cset holds those csses and makes them
easily accessible.
* All threaded csets are linked on their dom_csets to enable iteration
of all threaded tasks.
* cgroup->nr_threaded_children keeps track of the number of threaded
children.
This patch adds the above but doesn't actually use them yet. The
following patches will build on top.
v4: ->nr_threaded_children added.
v3: ->proc_cgrp/cset renamed to ->dom_cgrp/cset. Updated for the new
enable-threaded-per-cgroup behavior.
v2: Added cgroup_is_threaded() helper.
Signed-off-by: Tejun Heo <tj@kernel.org>
css_task_iter currently always walks all tasks. With the scheduled
cgroup v2 thread support, the iterator would need to handle multiple
types of iteration. As a preparation, add @flags to
css_task_iter_start() and implement CSS_TASK_ITER_PROCS. If the flag
is not specified, it walks all tasks as before. When asserted, the
iterator only walks the group leaders.
For now, the only user of the flag is cgroup v2 "cgroup.procs" file
which no longer needs to skip non-leader tasks in cgroup_procs_next().
Note that cgroup v1 "cgroup.procs" can't use the group leader walk as
v1 "cgroup.procs" doesn't mean "list all thread group leaders in the
cgroup" but "list all thread group id's with any threads in the
cgroup".
While at it, update cgroup_procs_show() to use task_pid_vnr() instead
of task_tgid_vnr(). As the iteration guarantees that the function
only sees group leaders, this doesn't change the output and will allow
sharing the function for thread iteration.
Signed-off-by: Tejun Heo <tj@kernel.org>
Currently, writes "cgroup.procs" and "cgroup.tasks" files are all
handled by __cgroup_procs_write() on both v1 and v2. This patch
reoragnizes the write path so that there are common helper functions
that different write paths use.
While this somewhat increases LOC, the different paths are no longer
intertwined and each path has more flexibility to implement different
behaviors which will be necessary for the planned v2 thread support.
v3: - Restructured so that cgroup_procs_write_permission() takes
@src_cgrp and @dst_cgrp.
v2: - Rolled in Waiman's task reference count fix.
- Updated on top of nsdelegate changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Waiman Long <longman@redhat.com>
On subsystem registration, css_populate_dir() is not called on the new
root css, so the interface files for the subsystem on cgrp_dfl_root
aren't created on registration. This is a residue from the days when
cgrp_dfl_root was used only as the parking spot for unused subsystems,
which no longer is true as it's used as the root for cgroup2.
This is often fine as later operations tend to create them as a part
of mount (cgroup1) or subtree_control operations (cgroup2); however,
it's not difficult to mount cgroup2 with the controller interface
files missing as Waiman found out.
Fix it by invoking css_populate_dir() on the root css on subsys
registration.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org # v4.5+
Signed-off-by: Tejun Heo <tj@kernel.org>
Implement trivial cgroup_has_tasks() which tests whether
cgrp->nr_populated_csets is zero and replace the explicit local
populated test in cgroup_subtree_control(). This simplifies the code
and cgroup_has_tasks() will be used in more places later.
Signed-off-by: Tejun Heo <tj@kernel.org>
cgrp->populated_cnt counts both local (the cgroup's populated
css_sets) and subtree proper (populated children) so that it's only
zero when the whole subtree, including self, is empty.
This patch splits the counter into two so that local and children
populated states are tracked separately. It allows finer-grained
tests on the state of the hierarchy which will be used to replace
css_set walking local populated test.
Signed-off-by: Tejun Heo <tj@kernel.org>
Subsystem migration methods shouldn't be called for empty migrations.
cgroup_migrate_execute() implements this guarantee by bailing early if
there are no source css_sets. This used to be correct before
a79a908fd2 ("cgroup: introduce cgroup namespaces"), but no longer
since the commit because css_sets can stay pinned without tasks in
them.
This caused cgroup_migrate_execute() call into cpuset migration
methods with an empty cgroup_taskset. cpuset migration methods
correctly assume that cgroup_taskset_first() never returns NULL;
however, due to the bug, it can, leading to the following oops.
Unable to handle kernel paging request for data at address 0x00000960
Faulting instruction address: 0xc0000000001d6868
Oops: Kernel access of bad area, sig: 11 [#1]
...
CPU: 14 PID: 16947 Comm: kworker/14:0 Tainted: G W
4.12.0-rc4-next-20170609 #2
Workqueue: events cpuset_hotplug_workfn
task: c00000000ca60580 task.stack: c00000000c728000
NIP: c0000000001d6868 LR: c0000000001d6858 CTR: c0000000001d6810
REGS: c00000000c72b720 TRAP: 0300 Tainted: GW (4.12.0-rc4-next-20170609)
MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 44722422 XER: 20000000
CFAR: c000000000008710 DAR: 0000000000000960 DSISR: 40000000 SOFTE: 1
GPR00: c0000000001d6858 c00000000c72b9a0 c000000001536e00 0000000000000000
GPR04: c00000000c72b9c0 0000000000000000 c00000000c72bad0 c000000766367678
GPR08: c000000766366d10 c00000000c72b958 c000000001736e00 0000000000000000
GPR12: c0000000001d6810 c00000000e749300 c000000000123ef8 c000000775af4180
GPR16: 0000000000000000 0000000000000000 c00000075480e9c0 c00000075480e9e0
GPR20: c00000075480e8c0 0000000000000001 0000000000000000 c00000000c72ba20
GPR24: c00000000c72baa0 c00000000c72bac0 c000000001407248 c00000000c72ba20
GPR28: c00000000141fc80 c00000000c72bac0 c00000000c6bc790 0000000000000000
NIP [c0000000001d6868] cpuset_can_attach+0x58/0x1b0
LR [c0000000001d6858] cpuset_can_attach+0x48/0x1b0
Call Trace:
[c00000000c72b9a0] [c0000000001d6858] cpuset_can_attach+0x48/0x1b0 (unreliable)
[c00000000c72ba00] [c0000000001cbe80] cgroup_migrate_execute+0xb0/0x450
[c00000000c72ba80] [c0000000001d3754] cgroup_transfer_tasks+0x1c4/0x360
[c00000000c72bba0] [c0000000001d923c] cpuset_hotplug_workfn+0x86c/0xa20
[c00000000c72bca0] [c00000000011aa44] process_one_work+0x1e4/0x580
[c00000000c72bd30] [c00000000011ae78] worker_thread+0x98/0x5c0
[c00000000c72bdc0] [c000000000124058] kthread+0x168/0x1b0
[c00000000c72be30] [c00000000000b2e8] ret_from_kernel_thread+0x5c/0x74
Instruction dump:
f821ffa1 7c7d1b78 60000000 60000000 38810020 7fa3eb78 3f42ffed 4bff4c25
60000000 3b5a0448 3d420020 eb610020 <e9230960> 7f43d378 e9290000 f92af200
---[ end trace dcaaf98fb36d9e64 ]---
This patch fixes the bug by adding an explicit nr_tasks counter to
cgroup_taskset and skipping calling the migration methods if the
counter is zero. While at it, remove the now spurious check on no
source css_sets.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: stable@vger.kernel.org # v4.6+
Fixes: a79a908fd2 ("cgroup: introduce cgroup namespaces")
Link: http://lkml.kernel.org/r/1497266622.15415.39.camel@abdul.in.ibm.com
Currently, cgroup only supports delegation to !root users and cgroup
namespaces don't get any special treatments. This limits the
usefulness of cgroup namespaces as they by themselves can't be safe
delegation boundaries. A process inside a cgroup can change the
resource control knobs of the parent in the namespace root and may
move processes in and out of the namespace if cgroups outside its
namespace are visible somehow.
This patch adds a new mount option "nsdelegate" which makes cgroup
namespaces delegation boundaries. If set, cgroup behaves as if write
permission based delegation took place at namespace boundaries -
writes to the resource control knobs from the namespace root are
denied and migration crossing the namespace boundary aren't allowed
from inside the namespace.
This allows cgroup namespace to function as a delegation boundary by
itself.
v2: Silently ignore nsdelegate specified on !init mounts.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Aravind Anbudurai <aru7@fb.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Restructure cgroup_procs_write_permission() to make extending
permission logic easier.
This patch doesn't cause any functional changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
The reference count in the css_set data structure was used as a
proxy of the number of tasks attached to that css_set. However, that
count is actually not an accurate measure especially with thread mode
support. So a new variable nr_tasks is added to the css_set to keep
track of the actual task count. This new variable is protected by
the css_set_lock. Functions that require the actual task count are
updated to use the new variable.
tj: s/task_count/nr_tasks/ for consistency with cgroup_root->nr_cgrps.
Refreshed on top of cgroup/for-v4.13 which dropped on
css_set_populated() -> nr_tasks conversion.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The kill_css() function may be called more than once under the condition
that the css was killed but not physically removed yet followed by the
removal of the cgroup that is hosting the css. This patch prevents any
harmm from being done when that happens.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # v4.5+
Pull cgroup updates from Tejun Heo:
"Nothing major. Two notable fixes are Li's second stab at fixing the
long-standing race condition in the mount path and suppression of
spurious warning from cgroup_get(). All other changes are trivial"
* 'for-4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: mark cgroup_get() with __maybe_unused
cgroup: avoid attaching a cgroup root to two different superblocks, take 2
cgroup: fix spurious warnings on cgroup_is_dead() from cgroup_sk_alloc()
cgroup: move cgroup_subsys_state parent field for cache locality
cpuset: Remove cpuset_update_active_cpus()'s parameter.
cgroup: switch to BUG_ON()
cgroup: drop duplicate header nsproxy.h
kernel: convert css_set.refcount from atomic_t to refcount_t
kernel: convert cgroup_namespace.count from atomic_t to refcount_t
a590b90d47 ("cgroup: fix spurious warnings on cgroup_is_dead() from
cgroup_sk_alloc()") converted most cgroup_get() usages to
cgroup_get_live() leaving cgroup_sk_alloc() the sole user of
cgroup_get(). When !CONFIG_SOCK_CGROUP_DATA, this ends up triggering
unused warning for cgroup_get().
Silence the warning by adding __maybe_unused to cgroup_get().
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/20170501145340.17e8ef86@canb.auug.org.au
Signed-off-by: Tejun Heo <tj@kernel.org>
Commit bfb0b80db5 ("cgroup: avoid attaching a cgroup root to two
different superblocks") is broken. Now we try to fix the race by
delaying the initialization of cgroup root refcnt until a superblock
has been allocated.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reported-by: Andrei Vagin <avagin@virtuozzo.com>
Tested-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
cgroup_get() expected to be called only on live cgroups and triggers
warning on a dead cgroup; however, cgroup_sk_alloc() may be called
while cloning a socket which is left in an empty and removed cgroup
and thus may legitimately duplicate its reference on a dead cgroup.
This currently triggers the following warning spuriously.
WARNING: CPU: 14 PID: 0 at kernel/cgroup.c:490 cgroup_get+0x55/0x60
...
[<ffffffff8107e123>] __warn+0xd3/0xf0
[<ffffffff8107e20e>] warn_slowpath_null+0x1e/0x20
[<ffffffff810ff465>] cgroup_get+0x55/0x60
[<ffffffff81106061>] cgroup_sk_alloc+0x51/0xe0
[<ffffffff81761beb>] sk_clone_lock+0x2db/0x390
[<ffffffff817cce06>] inet_csk_clone_lock+0x16/0xc0
[<ffffffff817e8173>] tcp_create_openreq_child+0x23/0x4b0
[<ffffffff818601a1>] tcp_v6_syn_recv_sock+0x91/0x670
[<ffffffff817e8b16>] tcp_check_req+0x3a6/0x4e0
[<ffffffff81861ba3>] tcp_v6_rcv+0x693/0xa00
[<ffffffff81837429>] ip6_input_finish+0x59/0x3e0
[<ffffffff81837cb2>] ip6_input+0x32/0xb0
[<ffffffff81837387>] ip6_rcv_finish+0x57/0xa0
[<ffffffff81837ac8>] ipv6_rcv+0x318/0x4d0
[<ffffffff817778c7>] __netif_receive_skb_core+0x2d7/0x9a0
[<ffffffff81777fa6>] __netif_receive_skb+0x16/0x70
[<ffffffff81778023>] netif_receive_skb_internal+0x23/0x80
[<ffffffff817787d8>] napi_gro_frags+0x208/0x270
[<ffffffff8168a9ec>] mlx4_en_process_rx_cq+0x74c/0xf40
[<ffffffff8168b270>] mlx4_en_poll_rx_cq+0x30/0x90
[<ffffffff81778b30>] net_rx_action+0x210/0x350
[<ffffffff8188c426>] __do_softirq+0x106/0x2c7
[<ffffffff81082bad>] irq_exit+0x9d/0xa0 [<ffffffff8188c0e4>] do_IRQ+0x54/0xd0
[<ffffffff8188a63f>] common_interrupt+0x7f/0x7f <EOI>
[<ffffffff8173d7e7>] cpuidle_enter+0x17/0x20
[<ffffffff810bdfd9>] cpu_startup_entry+0x2a9/0x2f0
[<ffffffff8103edd1>] start_secondary+0xf1/0x100
This patch renames the existing cgroup_get() with the dead cgroup
warning to cgroup_get_live() after cgroup_kn_lock_live() and
introduces the new cgroup_get() which doesn't check whether the cgroup
is live or dead.
All existing cgroup_get() users except for cgroup_sk_alloc() are
converted to use cgroup_get_live().
Fixes: d979a39d72 ("cgroup: duplicate cgroup reference when cloning sockets")
Cc: stable@vger.kernel.org # v4.5+
Cc: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Chris Mason <clm@fb.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Tejun Heo
Roman Gushchin
Arnd Bergmann
Ma Shimiao
Linus Torvalds
David S. Miller
Alexei Starovoitov
Waiman Long
Dan Carpenter
Shaohua Li
Zefan Li