On Wed 06-01-16 20:49:23, Tetsuo Handa wrote: > Michal Hocko wrote: > > On Tue 05-01-16 17:22:46, Michal Hocko wrote: > > > On Wed 30-12-15 15:33:47, Tetsuo Handa wrote: > > [...] > > > > I wish for a kernel thread that does OOM-kill operation. > > > > Maybe we can change the OOM reaper kernel thread to do it. > > > > What do you think? > > > > > > I do no think a separate kernel thread would help much if the > > > allocations have to keep looping in the allocator. oom_reaper is a > > > separate kernel thread only due to locking required for the exit_mmap > > > path. > > > > Let me clarify what I've meant here. What you actually want is to do > > select_bad_process and oom_kill_process (including oom_reap_vmas) in > > the kernel thread context, right? > > Right. It still seems we were not on the same page. I thought you wanted to make _all_ oom killer handling to be done from the kernel thread while you only cared about the sysrq+f case. Your patch below sounds like a reasonable compromise to me. It conflates two different things together but they are not that different in principle so I guess this could be acceptable. Maybe s@oom_reaper@async_oom_killer@ would be more appropriate to reflect that fact. [...] > While testing above patch, I once hit depletion of memory reserves. [...] > Complete log is at http://I-love.SAKURA.ne.jp/tmp/serial-20160106.txt.xz . > > I don't think this depletion was caused by above patch because the last > invocation was not SysRq-f. Yes I agree this is not related to the patch. > I believe we should add a workaround for > the worst case now. It is impossible to add it after we made the code > more and more difficult to test. > > > We would have to handle queuing of the > > oom requests because multiple oom killers might be active in different > > allocation domains (cpusets, memcgs) so I am not so sure this would be a > > great win in the end. But I haven't tried to do it so I might be wrong > > and it will turn up being much more easier than I expect. > > I could not catch what you want to say. I was contemplating about all the OOM killer handling from within the kernel thread as that was my understanding of what you were proposing. > If you are worrying about failing > to call oom_reap_vmas() for second victim due to invoking the OOM killer > again before mm_to_reap is updated from first victim to NULL, we can walk > on the process list. [...] Thanks! -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>