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Mel Gorman 748d2e9585 sched/core: Do not requeue task on CPU excluded from cpus_mask
[ Upstream commit 751d4cbc43 ]

The following warning was triggered on a large machine early in boot on
a distribution kernel but the same problem should also affect mainline.

   WARNING: CPU: 439 PID: 10 at ../kernel/workqueue.c:2231 process_one_work+0x4d/0x440
   Call Trace:
    <TASK>
    rescuer_thread+0x1f6/0x360
    kthread+0x156/0x180
    ret_from_fork+0x22/0x30
    </TASK>

Commit c6e7bd7afa ("sched/core: Optimize ttwu() spinning on p->on_cpu")
optimises ttwu by queueing a task that is descheduling on the wakelist,
but does not check if the task descheduling is still allowed to run on that CPU.

In this warning, the problematic task is a workqueue rescue thread which
checks if the rescue is for a per-cpu workqueue and running on the wrong CPU.
While this is early in boot and it should be possible to create workers,
the rescue thread may still used if the MAYDAY_INITIAL_TIMEOUT is reached
or MAYDAY_INTERVAL and on a sufficiently large machine, the rescue
thread is being used frequently.

Tracing confirmed that the task should have migrated properly using the
stopper thread to handle the migration. However, a parallel wakeup from udev
running on another CPU that does not share CPU cache observes p->on_cpu and
uses task_cpu(p), queues the task on the old CPU and triggers the warning.

Check that the wakee task that is descheduling is still allowed to run
on its current CPU and if not, wait for the descheduling to complete
and select an allowed CPU.

Fixes: c6e7bd7afa ("sched/core: Optimize ttwu() spinning on p->on_cpu")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20220804092119.20137-1-mgorman@techsingularity.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-08-17 14:24:15 +02:00
Documentation media: hevc: Embedded indexes in RPS 2022-08-17 14:23:31 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
arch x86/numa: Use cpumask_available instead of hardcoded NULL check 2022-08-17 14:24:15 +02:00
block block: ensure iov_iter advances for added pages 2022-08-17 14:24:01 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: memneq - move into lib/ 2022-06-22 14:22:03 +02:00
drivers video: fbdev: arkfb: Fix a divide-by-zero bug in ark_set_pixclock() 2022-08-17 14:24:15 +02:00
fs f2fs: fix to remove F2FS_COMPR_FL and tag F2FS_NOCOMP_FL at the same time 2022-08-17 14:24:13 +02:00
include sched, cpuset: Fix dl_cpu_busy() panic due to empty cs->cpus_allowed 2022-08-17 14:24:14 +02:00
init stack: Declare {randomize_,}kstack_offset to fix Sparse warnings 2022-08-17 14:23:10 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-09 10:23:10 +02:00
kernel sched/core: Do not requeue task on CPU excluded from cpus_mask 2022-08-17 14:24:15 +02:00
lib lib/smp_processor_id: fix imbalanced instrumentation_end() call 2022-08-17 14:24:08 +02:00
mm mm/mmap.c: fix missing call to vm_unacct_memory in mmap_region 2022-08-17 14:23:58 +02:00
net net: 9p: fix refcount leak in p9_read_work() error handling 2022-08-17 14:24:08 +02:00
samples samples/landlock: Format with clang-format 2022-06-09 10:23:23 +02:00
scripts scripts/faddr2line: Fix vmlinux detection on arm64 2022-08-17 14:24:14 +02:00
security selinux: Add boundary check in put_entry() 2022-08-17 14:23:05 +02:00
sound ASoC: mchp-spdifrx: disable end of block interrupt on failures 2022-08-17 14:24:11 +02:00
tools tools/thermal: Fix possible path truncations 2022-08-17 14:24:15 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: Don't set Accessed/Dirty bits for ZERO_PAGE 2022-08-17 14:23:44 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Input: goodix - add a goodix.h header file 2022-07-12 16:34:51 +02:00
Makefile Makefile: link with -z noexecstack --no-warn-rwx-segments 2022-08-17 14:22:44 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.