On Sun, May 3, 2020 at 11:57 PM Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > On Thu 30-04-20 13:20:10, Shakeel Butt wrote: > > On Thu, Apr 30, 2020 at 12:29 PM Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > > > > > > On Thu, Apr 30, 2020 at 11:27:12AM -0700, Shakeel Butt wrote: > > > > Lowering memory.max can trigger an oom-kill if the reclaim does not > > > > succeed. However if oom-killer does not find a process for killing, it > > > > dumps a lot of warnings. > > > > > > > > Deleting a memcg does not reclaim memory from it and the memory can > > > > linger till there is a memory pressure. One normal way to proactively > > > > reclaim such memory is to set memory.max to 0 just before deleting the > > > > memcg. However if some of the memcg's memory is pinned by others, this > > > > operation can trigger an oom-kill without any process and thus can log a > > > > lot un-needed warnings. So, ignore all such warnings from memory.max. > > > > > > Can't you set memory.high=0 instead? It does the reclaim portion of > > > memory.max, without the actual OOM killing that causes you problems. > > > > Yes that would work but remote charging concerns me. Remote charging > > can still happen after the memcg is offlined and at the moment, high > > reclaim does not work for remote memcg and the usage can go till max > > or global pressure. This is most probably a misconfiguration and we > > might not receive the warnings in the log ever. Setting memory.max to > > 0 will definitely give such warnings. > > Can we add a warning for the remote charging on dead memcgs? > I don't think we should warn for all remote charging on dead memcgs. One particular example is the buffer_head which can be allocated within reclaim context and most probably pages which they are attached to will be freed soon. Shakeel
