4.20-stable review patch. If anyone has any objections, please let me know.
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From: Michal Hocko mhocko@suse.com
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@kernel.org Fixes: 29ef680ae7c2 ("memcg, oom: move out_of_memory back to the charge path") Signed-off-by: Michal Hocko mhocko@suse.com Reported-by: Burt Holzman burt@fnal.gov Acked-by: Johannes Weiner hannes@cmpxchg.org Cc: Vladimir Davydov <vdavydov.dev@gmail.com Cc: stable@vger.kernel.org [4.19+] Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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; }
/**