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Yafang Shao 04fd61a4e0 mm, memcg: fix inconsistent oom event behavior
A recent commit 9852ae3fe5 ("mm, memcg: consider subtrees in
memory.events") changed the behavior of memcg events, which will now
consider subtrees in memory.events.

But oom_kill event is a special one as it is used in both cgroup1 and
cgroup2.  In cgroup1, it is displayed in memory.oom_control.  The file
memory.oom_control is in both root memcg and non root memcg, that is
different with memory.event as it only in non-root memcg.  That commit
is okay for cgroup2, but it is not okay for cgroup1 as it will cause
inconsistent behavior between root memcg and non-root memcg.

Here's an example on why this behavior is inconsistent in cgroup1.

       root memcg
       /
    memcg foo
     /
  memcg bar

Suppose there's an oom_kill in memcg bar, then the oon_kill will be

       root memcg : memory.oom_control(oom_kill)  0
       /
    memcg foo : memory.oom_control(oom_kill)  1
     /
  memcg bar : memory.oom_control(oom_kill)  1

For the non-root memcg, its memory.oom_control(oom_kill) includes its
descendants' oom_kill, but for root memcg, it doesn't include its
descendants' oom_kill.  That means, memory.oom_control(oom_kill) has
different meanings in different memcgs.  That is inconsistent.  Then the
user has to know whether the memcg is root or not.

If we can't fully support it in cgroup1, for example by adding
memory.events.local into cgroup1 as well, then let's don't touch its
original behavior.

Fixes: 9852ae3fe5 ("mm, memcg: consider subtrees in memory.events")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Chris Down <chris@chrisdown.name>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200502141055.7378-1-laoar.shao@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-05-14 10:00:35 -07:00
arch A set of fixes for x86: 2020-05-10 11:59:53 -07:00
block bdi: use bdi_dev_name() to get device name 2020-05-09 16:07:39 -06:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto gcc-10: avoid shadowing standard library 'free()' in crypto 2020-05-09 15:58:04 -07:00
Documentation Bugfixes, mostly for ARM and AMD, and more documentation. 2020-05-07 09:50:59 -07:00
drivers Some GPIO fixes for the v5.7 kernel: 2020-05-12 10:39:34 -07:00
fs Various gfs2 fixes 2020-05-12 10:32:32 -07:00
include mm, memcg: fix inconsistent oom event behavior 2020-05-14 10:00:35 -07:00
init Tracing fixes to previous fixes: 2020-05-12 11:06:26 -07:00
ipc ipc/mqueue.c: change __do_notify() to bypass check_kill_permission() 2020-05-07 19:27:20 -07:00
kernel Tracing fixes to previous fixes: 2020-05-12 11:06:26 -07:00
lib ubsan: disable UBSAN_ALIGNMENT under COMPILE_TEST 2020-05-07 19:27:21 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm block-5.7-2020-05-09 2020-05-10 11:16:07 -07:00
net Fixes: 2020-05-11 12:04:52 -07:00
samples tracing: Fix doc mistakes in trace sample 2020-05-07 13:32:57 -04:00
scripts scripts/gdb: repair rb_first() and rb_last() 2020-05-07 19:27:20 -07:00
security selinux/stable-5.7 PR 20200430 2020-04-30 16:35:45 -07:00
sound sound fixes for 5.7-rc4 2020-05-01 11:05:28 -07:00
tools Tracing fixes to previous fixes: 2020-05-12 11:06:26 -07:00
usr kbuild: fix comment about missing include guard detection 2020-04-11 12:09:48 +09:00
virt KVM: arm64: Fix 32bit PC wrap-around 2020-05-01 09:51:08 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2020-04-18 13:49:33 +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: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
.mailmap mailmap: Add Sedat Dilek (replacement for expired email address) 2020-04-11 09:28:34 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Hand MIPS over to Thomas 2020-02-24 22:43:18 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Fixes for an endianness handling bug that prevented mounts on 2020-05-08 10:27:00 -07:00
Makefile Linux 5.7-rc5 2020-05-10 15:16:58 -07:00
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.