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Re: [RFC 1/3] mm, oom: refactor oom detection

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On Fri 30-10-15 18:41:30, KAMEZAWA Hiroyuki wrote:
[...]
> >>So, now, 0-order page allocation may fail in a OOM situation ?
> >
> >No they don't normally and this patch doesn't change the logic here.
> >
> 
> I understand your patch doesn't change the behavior.
> Looking into __alloc_pages_may_oom(), *did_some_progress is finally set by
> 
>      if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL))
>                 *did_some_progress = 1;
> 
> ...depends on out_of_memory() return value.
> Now, allocation may fail if oom-killer is disabled.... Isn't it complicated ?

Yes and there shouldn't be any allocations after OOM killer has been
disabled. The userspace is already frozen and there shouldn't be any
other memory activity.
 
> Shouldn't we have
> 
>  if (order < PAGE_ALLOC_COSTLY_ORDER)
>     goto retry;
> 
> here ?

How could we move on during the suspend if the reclaim doesn't proceed
and we cannot really kill anything to free up memory resources. We are
simply past the moment any userspace can be woken up. Anyway this is
tangent to this particular patch series.

-- 
Michal Hocko
SUSE Labs
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RFC: OOM detection rework v1 mhocko@kernel.org - 2015-10-29 16:20 +0100
  [RFC 3/3] mm: use watermak checks for __GFP_REPEAT high order allocations mhocko@kernel.org - 2015-10-29 16:20 +0100
  [RFC 1/3] mm, oom: refactor oom detection mhocko@kernel.org - 2015-10-29 16:20 +0100
    Re: [RFC 1/3] mm, oom: refactor oom detection "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2015-10-30 05:20 +0100
      Re: [RFC 1/3] mm, oom: refactor oom detection Michal Hocko <mhocko@kernel.org> - 2015-10-30 09:40 +0100
        Re: [RFC 1/3] mm, oom: refactor oom detection Michal Hocko <mhocko@kernel.org> - 2015-10-30 11:20 +0100
          Re: [RFC 1/3] mm, oom: refactor oom detection Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-10-30 14:40 +0100
            Re: [RFC 1/3] mm, oom: refactor oom detection Michal Hocko <mhocko@kernel.org> - 2015-10-30 16:00 +0100
          Re: [RFC 1/3] mm, oom: refactor oom detection "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2015-10-31 05:00 +0100
    Re: [RFC 1/3] mm, oom: refactor oom detection Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> - 2015-10-30 06:30 +0100
      Re: [RFC 1/3] mm, oom: refactor oom detection Michal Hocko <mhocko@kernel.org> - 2015-10-30 09:30 +0100
        Re: [RFC 1/3] mm, oom: refactor oom detection Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> - 2015-10-30 10:50 +0100
          Re: [RFC 1/3] mm, oom: refactor oom detection Michal Hocko <mhocko@kernel.org> - 2015-10-30 11:20 +0100
  [RFC 2/3] mm: throttle on IO only when there are too many dirty and writeback pages mhocko@kernel.org - 2015-10-29 16:20 +0100
    Re: [RFC 2/3] mm: throttle on IO only when there are too many dirty and writeback pages "Hillf Danton" <hillf.zj@alibaba-inc.com> - 2015-10-30 05:30 +0100
      Re: [RFC 2/3] mm: throttle on IO only when there are too many dirty  and writeback pages Michal Hocko <mhocko@kernel.org> - 2015-10-30 09:40 +0100
    Re: [RFC 2/3] mm: throttle on IO only when there are too many dirty  and writeback pages Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> - 2015-10-30 06:50 +0100
      Re: [RFC 2/3] mm: throttle on IO only when there are too many dirty  and writeback pages Michal Hocko <mhocko@kernel.org> - 2015-10-30 09:40 +0100

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