Commit db33ec37 authored by Konstantin Khlebnikov's avatar Konstantin Khlebnikov Committed by Linus Torvalds
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doc: cgroup: update note about conditions when oom killer is invoked 



Starting from v4.19 commit 29ef680a ("memcg, oom: move out_of_memory
back to the charge path") cgroup oom killer is no longer invoked only
from page faults.  Now it implements the same semantics as global OOM
killer: allocation context invokes OOM killer and keeps retrying until
success.

[akpm@linux-foundation.org: fixes per Randy]

Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Link: http://lkml.kernel.org/r/158894738928.208854.5244393925922074518.stgit@buzz


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 490741ab

Documentation/admin-guide/cgroup-v2.rst

+8 −9
Original line number Diff line number Diff line
@@ -1170,6 +1170,13 @@ PAGE_SIZE multiple when read back. 
	Under certain circumstances, the usage may go over the limit

	temporarily.



	In default configuration regular 0-order allocations always

	succeed unless OOM killer chooses current task as a victim.



	Some kinds of allocations don't invoke the OOM killer.

	Caller could retry them differently, return into userspace

	as -ENOMEM or silently ignore in cases like disk readahead.



	This is the ultimate protection mechanism.  As long as the

	high limit is used and monitored properly, this limit's

	utility is limited to providing the final safety net.
@@ -1226,17 +1233,9 @@ PAGE_SIZE multiple when read back. 
		The number of time the cgroup's memory usage was

		reached the limit and allocation was about to fail.



		Depending on context result could be invocation of OOM

		killer and retrying allocation or failing allocation.



		Failed allocation in its turn could be returned into

		userspace as -ENOMEM or silently ignored in cases like

		disk readahead.  For now OOM in memory cgroup kills

		tasks iff shortage has happened inside page fault.



		This event is not raised if the OOM killer is not

		considered as an option, e.g. for failed high-order

		allocations.

		allocations or if caller asked to not retry attempts.



	  oom_kill

		The number of processes belonging to this cgroup

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