Since commit 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the
charge path") memcg invokes oom killer not only for user page-faults.
This means 0-order allocation will either succeed or task get killed.
Fixes: 8e675f7af507 ("mm/oom_kill: count global and memory cgroup oom kills")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
---
Documentation/admin-guide/cgroup-v2.rst | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 5361ebec3361..eb47815e137b 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -1219,8 +1219,13 @@ PAGE_SIZE multiple when read back.
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.
+ disk readahead.
+
+ Before 4.19 OOM in memory cgroup killed tasks iff
+ shortage has happened inside page fault, random
+ syscall may fail with ENOMEM or EFAULT. Since 4.19
+ failed memory cgroup allocation invokes oom killer and
+ keeps retrying until it succeeds.
This event is not raised if the OOM killer is not
considered as an option, e.g. for failed high-order
