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Mel Gorman b485c6f1f9 mm: vmscan: remove deadlock due to throttling failing to make progress
A soft lockup bug in kcompactd was reported in a private bugzilla with
the following visible in dmesg;

  watchdog: BUG: soft lockup - CPU#33 stuck for 26s! [kcompactd0:479]
  watchdog: BUG: soft lockup - CPU#33 stuck for 52s! [kcompactd0:479]
  watchdog: BUG: soft lockup - CPU#33 stuck for 78s! [kcompactd0:479]
  watchdog: BUG: soft lockup - CPU#33 stuck for 104s! [kcompactd0:479]

The machine had 256G of RAM with no swap and an earlier failed
allocation indicated that node 0 where kcompactd was run was potentially
unreclaimable;

  Node 0 active_anon:29355112kB inactive_anon:2913528kB active_file:0kB
    inactive_file:0kB unevictable:64kB isolated(anon):0kB isolated(file):0kB
    mapped:8kB dirty:0kB writeback:0kB shmem:26780kB shmem_thp:
    0kB shmem_pmdmapped: 0kB anon_thp: 23480320kB writeback_tmp:0kB
    kernel_stack:2272kB pagetables:24500kB all_unreclaimable? yes

Vlastimil Babka investigated a crash dump and found that a task
migrating pages was trying to drain PCP lists;

  PID: 52922  TASK: ffff969f820e5000  CPU: 19  COMMAND: "kworker/u128:3"
  Call Trace:
     __schedule
     schedule
     schedule_timeout
     wait_for_completion
     __flush_work
     __drain_all_pages
     __alloc_pages_slowpath.constprop.114
     __alloc_pages
     alloc_migration_target
     migrate_pages
     migrate_to_node
     do_migrate_pages
     cpuset_migrate_mm_workfn
     process_one_work
     worker_thread
     kthread
     ret_from_fork

This failure is specific to CONFIG_PREEMPT=n builds.  The root of the
problem is that kcompact0 is not rescheduling on a CPU while a task that
has isolated a large number of the pages from the LRU is waiting on
kcompact0 to reschedule so the pages can be released.  While
shrink_inactive_list() only loops once around too_many_isolated, reclaim
can continue without rescheduling if sc->skipped_deactivate == 1 which
could happen if there was no file LRU and the inactive anon list was not
low.

Link: https://lkml.kernel.org/r/20220203100326.GD3301@suse.de
Fixes: d818fca1ca ("mm/vmscan: throttle reclaim and compaction when too may pages are isolated")
Signed-off-by: Mel Gorman <mgorman@suse.de>
Debugged-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-02-11 17:55:00 -08:00
arch - device tree fix for Ingenic CI20 2022-02-10 05:52:00 -08:00
block block: bio-integrity: Advance seed correctly for larger interval sizes 2022-02-03 21:09:24 -07:00
certs certs: Fix build error when CONFIG_MODULE_SIG_KEY is empty 2022-01-23 00:08:44 +09:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2022-02-09 09:53:56 -08:00
Documentation linux-kselftest-kunit-fixes-5.17-rc4 2022-02-10 15:39:59 -08:00
drivers Networking fixes for 5.17-rc4, including fixes from netfilter and can. 2022-02-10 16:01:22 -08:00
fs fs/proc: task_mmu.c: don't read mapcount for migration entry 2022-02-11 17:55:00 -08:00
include Networking fixes for 5.17-rc4, including fixes from netfilter and can. 2022-02-10 16:01:22 -08:00
init lib/stackdepot: allow optional init and stack_table allocation by kvmalloc() 2022-01-22 08:33:37 +02:00
ipc ipc/sem: do not sleep with a spin lock held 2022-02-04 09:25:05 -08:00
kernel audit/stable-5.17 PR 20220209 2022-02-10 05:43:43 -08:00
lib lib/crypto: blake2s: avoid indirect calls to compression function for Clang CFI 2022-02-04 19:22:32 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: vmscan: remove deadlock due to throttling failing to make progress 2022-02-11 17:55:00 -08:00
net Networking fixes for 5.17-rc4, including fixes from netfilter and can. 2022-02-10 16:01:22 -08:00
samples Merge branch 'akpm' (patches from Andrew) 2022-01-20 10:41:01 +02:00
scripts ftrace: Have architectures opt-in for mcount build time sorting 2022-01-27 19:15:44 -05:00
security integrity-v5-17-fix 2022-02-07 09:55:14 -08:00
sound ASoC: Fixes for v5.17 2022-02-01 16:52:54 +01:00
tools Networking fixes for 5.17-rc4, including fixes from netfilter and can. 2022-02-10 16:01:22 -08:00
usr kbuild: remove include/linux/cyclades.h from header file check 2022-01-27 08:51:08 +01:00
virt Two larger x86 series: 2022-01-28 19:00:26 +02:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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: update Christian Brauner's email address 2022-02-01 11:21:31 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Removing Ohad from remoteproc/rpmsg maintenance 2021-12-08 10:09:40 -07:00
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 Networking fixes for 5.17-rc4, including fixes from netfilter and can. 2022-02-10 16:01:22 -08:00
Makefile Linux 5.17-rc3 2022-02-06 12:20:50 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.