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authorKonstantin Khlebnikov <khlebnikov@yandex-team.ru>2020-05-30 14:51:17 +1000
committerStephen Rothwell <sfr@canb.auug.org.au>2020-06-02 19:28:40 +1000
commit1114699aa7f777234c3dc9be2cc49302bf53198d (patch)
tree10f105825c6d7fd06a2a38de75ffeb53d543c3ba
parent9fc1682ba9323fb58db70a42de4b7876ed40010b (diff)
downloadlinux-1114699aa7f777234c3dc9be2cc49302bf53198d.tar.gz
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. Link: http://lkml.kernel.org/r/158894738928.208854.5244393925922074518.stgit@buzz Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Roman Gushchin <guro@fb.com> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
-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..5f63f1ba0302 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 allocation always
+ succeed unless OOM killer choose 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