On 2018/07/09 16:57, Michal Hocko wrote: > On Sun 08-07-18 19:35:58, Tetsuo Handa wrote: >> From: Michal Hocko <mhocko@xxxxxxxx> >> >> should_reclaim_retry() should be a natural reschedule point. PF_WQ_WORKER >> is a special case which needs a stronger rescheduling policy. However, >> since schedule_timeout_uninterruptible(1) for PF_WQ_WORKER depends on >> __zone_watermark_ok() == true, PF_WQ_WORKER is currently counting on >> mutex_trylock(&oom_lock) == 0 in __alloc_pages_may_oom() which is a bad >> expectation. > > I think your reference to the oom_lock is more confusing than helpful > actually. I would simply use the following from your previous [1] > changelog: Then, you can post yourself because > : should_reclaim_retry() should be a natural reschedule point. PF_WQ_WORKER > : is a special case which needs a stronger rescheduling policy. Doing that > : unconditionally seems more straightforward than depending on a zone being > : a good candidate for a further reclaim. > : > : Thus, move the short sleep when we are waiting for the owner of oom_lock > : (which coincidentally also serves as a guaranteed sleep for PF_WQ_WORKER > : threads) to should_reclaim_retry(). > >> unconditionally seems more straightforward than depending on a zone being >> a good candidate for a further reclaim. > > [1] http://lkml.kernel.org/r/1528369223-7571-2-git-send-email-penguin-kernel@xxxxxxxxxxxxxxxxxxx > > [Tetsuo: changelog] >> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> >> Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> >> Cc: David Rientjes <rientjes@xxxxxxxxxx> >> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> >> Cc: Joonsoo Kim <js1304@xxxxxxxxx> >> Cc: Mel Gorman <mgorman@xxxxxxx> >> Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> >> Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> >> Cc: Vlastimil Babka <vbabka@xxxxxxx> > > Your s-o-b is still missing. all code changes in this patch is from you. That is, my s-o-b is not missing.
