On 2018/05/31 19:44, Michal Hocko wrote: > On Thu 31-05-18 19:10:48, Tetsuo Handa wrote: >> On 2018/05/30 8:07, Andrew Morton wrote: >>> On Tue, 29 May 2018 09:17:41 +0200 Michal Hocko <mhocko@xxxxxxxxxx> wrote: >>> >>>>> I suggest applying >>>>> this patch first, and then fix "mm, oom: cgroup-aware OOM killer" patch. >>>> >>>> Well, I hope the whole pile gets merged in the upcoming merge window >>>> rather than stall even more. >>> >>> I'm more inclined to drop it all. David has identified significant >>> shortcomings and I'm not seeing a way of addressing those shortcomings >>> in a backward-compatible fashion. Therefore there is no way forward >>> at present. >>> >> >> Can we apply my patch as-is first? > > No. As already explained before. Sprinkling new sleeps without a strong > reason is not acceptable. The issue you are seeing is pretty artificial > and as such doesn're really warrant an immediate fix. We should rather > go with a well thought trhough fix. In other words we should simply drop > the sleep inside the oom_lock for starter unless it causes some really > unexpected behavior change. > The OOM killer did not require schedule_timeout_killable(1) to return as long as the OOM victim can call __mmput(). But now the OOM killer requires schedule_timeout_killable(1) to return in order to allow the OOM victim to call __oom_reap_task_mm(). Thus, this is a regression. Artificial cannot become the reason to postpone my patch. If we don't care artificialness/maliciousness, we won't need to care Spectre/Meltdown bugs. I'm not sprinkling new sleeps. I'm just merging existing sleeps (i.e. mutex_trylock() case and !mutex_trylock() case) and updating the outdated comments.
