On Wed 25-10-17 15:49:21, Greg Thelen wrote: > Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > > > On Wed, Oct 25, 2017 at 09:00:57PM +0200, Michal Hocko wrote: [...] > >> So just to make it clear you would be OK with the retry on successful > >> OOM killer invocation and force charge on oom failure, right? > > > > Yeah, that sounds reasonable to me. > > Assuming we're talking about retrying within try_charge(), then there's > a detail to iron out... > > If there is a pending oom victim blocked on a lock held by try_charge() caller > (the "#2 Locks" case), then I think repeated calls to out_of_memory() will > return true until the victim either gets MMF_OOM_SKIP or disappears. true. And oom_reaper guarantees that MMF_OOM_SKIP gets set in the finit amount of time. > So a force > charge fallback might be a needed even with oom killer successful invocations. > Or we'll need to teach out_of_memory() to return three values (e.g. NO_VICTIM, > NEW_VICTIM, PENDING_VICTIM) and try_charge() can loop on NEW_VICTIM. No we, really want to wait for the oom victim to do its job. The only thing we should be worried about is when out_of_memory doesn't invoke the reaper. There is only one case like that AFAIK - GFP_NOFS request. I have to think about this case some more. We currently fail in that case the request. -- Michal Hocko SUSE Labs
