On Tue 08-01-19 19:39:58, Tetsuo Handa wrote: > On 2019/01/08 17:14, Michal Hocko wrote: > >>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c > >>> index af7f18b32389..90eb2e2093e7 100644 > >>> --- a/mm/memcontrol.c > >>> +++ b/mm/memcontrol.c > >>> @@ -1387,10 +1387,22 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask, > >>> .gfp_mask = gfp_mask, > >>> .order = order, > >>> }; > >>> - bool ret; > >>> + bool ret = true; > >>> > >>> mutex_lock(&oom_lock); > >> > >> And because of "[PATCH 1/2] mm, oom: marks all killed tasks as oom > >> victims", mark_oom_victim() will be called on current thread even if > >> we used mutex_lock_killable(&oom_lock) here, like you said > >> > >> mutex_lock_killable would take care of exiting task already. I would > >> then still prefer to check for mark_oom_victim because that is not racy > >> with the exit path clearing signals. I can update my patch to use > >> _killable lock variant if we are really going with the memcg specific > >> fix. > >> > >> . If current thread is not yet killed by the OOM killer but can terminate > >> without invoking the OOM killer, using mutex_lock_killable(&oom_lock) here > >> saves some processes. What is the race you are referring by "racy with the > >> exit path clearing signals" ? > > > > This is unrelated to the patch. > > Ultimately related! This is the reasoning why your patch should be preferred > over my patch. No! I've said I do not mind using mutex_lock_killable on top of this patch. I just want to have this fix minimal. -- Michal Hocko SUSE Labs
