4.20-stable review patch. If anyone has any objections, please let me know.
------------------
From: Michal Hocko <mhocko@xxxxxxxx>
commit 7056d3a37d2c6aaaab10c13e8e69adc67ec1fc65 upstream.
Burt Holzman has noticed that memcg v1 doesn't notify about OOM events via
eventfd anymore. The reason is that 29ef680ae7c2 ("memcg, oom: move
out_of_memory back to the charge path") has moved the oom handling back to
the charge path. While doing so the notification was left behind in
mem_cgroup_oom_synchronize.
Fix the issue by replicating the oom hierarchy locking and the
notification.
Link: http://lkml.kernel.org/r/20181224091107.18354-1-mhocko@xxxxxxxxxx
Fixes: 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the charge path")
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Reported-by: Burt Holzman <burt@xxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx> [4.19+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1666,6 +1666,9 @@ enum oom_status {
static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int order)
{
+ enum oom_status ret;
+ bool locked;
+
if (order > PAGE_ALLOC_COSTLY_ORDER)
return OOM_SKIPPED;
@@ -1700,10 +1703,23 @@ static enum oom_status mem_cgroup_oom(st
return OOM_ASYNC;
}
+ mem_cgroup_mark_under_oom(memcg);
+
+ locked = mem_cgroup_oom_trylock(memcg);
+
+ if (locked)
+ mem_cgroup_oom_notify(memcg);
+
+ mem_cgroup_unmark_under_oom(memcg);
if (mem_cgroup_out_of_memory(memcg, mask, order))
- return OOM_SUCCESS;
+ ret = OOM_SUCCESS;
+ else
+ ret = OOM_FAILED;
+
+ if (locked)
+ mem_cgroup_oom_unlock(memcg);
- return OOM_FAILED;
+ return ret;
}
/**
