On Tue 07-08-18 19:15:11, Tetsuo Handa wrote: [...] > Of course, if the hard limit is 0, all processes will be killed after all. But > Michal is ignoring the fact that if the hard limit were not 0, there is a chance > of saving next process from needlessly killed if we waited until "mm of PID=23766 > completed __mmput()" or "mm of PID=23766 failed to complete __mmput() within > reasonable period". This is a completely different issue IMHO. I haven't seen reports about overly eager memcg oom killing so far. > We can make efforts not to return false at > > /* > * This task has already been drained by the oom reaper so there are > * only small chances it will free some more > */ > if (test_bit(MMF_OOM_SKIP, &mm->flags)) > return false; > > (I admit that ignoring MMF_OOM_SKIP for once might not be sufficient for memcg > case), and we can use feedback based backoff like > "[PATCH 4/4] mm, oom: Fix unnecessary killing of additional processes." *UNTIL* > we come to the point where the OOM reaper can always reclaim all memory. The code is quite tricky and I am really reluctant to make it even more so without seeing this is really hurting real users with real workloads. -- Michal Hocko SUSE Labs
