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authorKonstantin Khlebnikov <khlebnikov@yandex-team.ru>2020-06-07 21:42:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-08 11:05:58 -0700
commitdb33ec371be8e45956e8cebb5b0fe641f008430b (patch)
tree82aa1e1d0e9dfaacfd04d41ad5215c4bf58dd3f3
parent490741ab1beb9c9f6580e30c7cd91b17a7560369 (diff)
downloadlinux-db33ec371be8e45956e8cebb5b0fe641f008430b.tar.bz2
doc: cgroup: update note about conditions when oom killer is invoked
Starting from v4.19 commit 29ef680ae7c2 ("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: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal 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: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--Documentation/admin-guide/cgroup-v2.rst17
1 files changed, 8 insertions, 9 deletions
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index c2a4b652bd1a..ce3e05e41724 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -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