Naresh Kamboju writes:
On Thu, 28 May 2020 at 20:33, Michal Hocko <mhocko@xxxxxxxxxx> wrote:On Fri 22-05-20 02:23:09, Naresh Kamboju wrote: > My apology ! > As per the test results history this problem started happening from > Bad : next-20200430 (still reproducible on next-20200519) > Good : next-20200429 > > The git tree / tag used for testing is from linux next-20200430 tag and reverted > following three patches and oom-killer problem fixed. > > Revert "mm, memcg: avoid stale protection values when cgroup is above > protection" > Revert "mm, memcg: decouple e{low,min} state mutations from protectinn checks" > Revert "mm-memcg-decouple-elowmin-state-mutations-from-protection-checks-fix" The discussion has fragmented and I got lost TBH. In http://lkml.kernel.org/r/CA+G9fYuDWGZx50UpD+WcsDeHX9vi3hpksvBAWbMgRZadb0Pkww@xxxxxxxxxxxxxx you have said that none of the added tracing output has triggered. Does this still hold? Because I still have a hard time to understand how those three patches could have the observed effects.On the other email thread [1] this issue is concluded. Yafang wrote on May 22 2020, Regarding the root cause, my guess is it makes a similar mistake that I tried to fix in the previous patch that the direct reclaimer read a stale protection value. But I don't think it is worth to add another fix. The best way is to revert this commit.
This isn't a conclusion, just a guess (and one I think is unlikely). For this to reliably happen, it implies that the same race happens the same way each time.
