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Re: System freezes after OOM

From Michal Hocko <mhocko@kernel.org>
Newsgroups linux.kernel
Subject Re: System freezes after OOM
Date 2016-07-18 09:30 +0200
Message-ID <rWba2-3by-27@gated-at.bofh.it> (permalink)
References (5 earlier) <rUSMa-4cH-25@gated-at.bofh.it> <rV6P7-4CX-15@gated-at.bofh.it> <rVag1-6Nq-1@gated-at.bofh.it> <rVapH-6QL-13@gated-at.bofh.it> <rVeMF-19a-15@gated-at.bofh.it>
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On Fri 15-07-16 13:02:17, Mikulas Patocka wrote:
> 
> 
> On Fri, 15 Jul 2016, Michal Hocko wrote:
> 
> > On Fri 15-07-16 08:11:22, Mikulas Patocka wrote:
> > > 
> > > The stacktraces showed that the kcryptd process was throttled when it 
> > > tried to do mempool allocation. Mempool adds the __GFP_NORETRY flag to the 
> > > allocation, but unfortunatelly, this flag doesn't prevent the allocator 
> > > from throttling.
> > 
> > Yes and in fact it shouldn't prevent any throttling. The flag merely
> > says that the allocation should give up rather than retry
> > reclaim/compaction again and again.
> > 
> > > I say that the process doing mempool allocation shouldn't ever be 
> > > throttled. Maybe add __GFP_NOTHROTTLE?
> > 
> > A specific gfp flag would be an option but we are slowly running out of
> > bit space there and I am not yet convinced PF_LESS_THROTTLE is
> > unsuitable.
> 
> PF_LESS_THROTTLE will make it throttle less, but it doesn't eliminate 
> throttling entirely. So, maybe add PF_NO_THROTTLE? But PF_* flags are also 
> almost exhausted.

I am not really sure we can make anybody so special to not throttle at all.
Seeing a congested backig device sounds like a reasonable compromise.
Besides that it seems that we do not really need to eliminate
wait_iff_congested for dm to work properly again AFAIU. I plan to repost
both patch today after some more internal review. If we need to do more
changes I would suggest making them in separet patches.
-- 
Michal Hocko
SUSE Labs

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Thread

Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-11 17:50 +0200
  Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-12 08:50 +0200
    Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-13 01:50 +0200
      Re: System freezes after OOM Jerome Marchand <jmarchan@redhat.com> - 2016-07-13 10:40 +0200
        Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-13 13:20 +0200
          Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-13 16:30 +0200
      Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-13 13:20 +0200
        Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-13 15:00 +0200
          Re: System freezes after OOM Milan Broz <gmazyland@gmail.com> - 2016-07-13 15:50 +0200
            Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-13 17:40 +0200
              Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-14 11:10 +0200
                Re: System freezes after OOM Milan Broz <gmazyland@gmail.com> - 2016-07-14 11:50 +0200
        Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-13 17:10 +0200
          Re: [dm-devel] System freezes after OOM Ondrej Kozina <okozina@redhat.com> - 2016-07-14 13:00 +0200
          Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-14 15:00 +0200
            Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-14 16:10 +0200
              Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-14 17:00 +0200
                Re: System freezes after OOM Ondrej Kozina <okozina@redhat.com> - 2016-07-14 17:30 +0200
                Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-14 19:40 +0200
                Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-15 10:40 +0200
                Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-15 14:20 +0200
                Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-15 14:30 +0200
                Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-15 19:10 +0200
                Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-18 09:30 +0200
            Re: System freezes after OOM Ondrej Kozina <okozina@redhat.com> - 2016-07-14 17:30 +0200
              Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-14 17:40 +0200
                Re: System freezes after OOM Ondrej Kozina <okozina@redhat.com> - 2016-07-14 19:10 +0200
                Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-14 19:40 +0200
                Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-14 19:40 +0200
                Re: System freezes after OOM Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-07-15 13:50 +0200
      Re: System freezes after OOM Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-07-13 15:30 +0200
        Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-13 15:50 +0200
          Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-13 16:30 +0200
            Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-13 17:00 +0200
              Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-13 17:20 +0200
                Re: System freezes after OOM David Rientjes <rientjes@google.com> - 2016-07-14 02:00 +0200
                Re: System freezes after OOM Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-07-14 13:10 +0200
                Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-14 14:30 +0200
                Re: System freezes after OOM David Rientjes <rientjes@google.com> - 2016-07-14 22:30 +0200
                Re: System freezes after OOM Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-07-14 23:50 +0200
                Re: System freezes after OOM David Rientjes <rientjes@google.com> - 2016-07-15 00:10 +0200
                Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-15 13:30 +0200
                Re: System freezes after OOM David Rientjes <rientjes@google.com> - 2016-07-15 23:30 +0200
                Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-14 14:30 +0200
                Re: System freezes after OOM David Rientjes <rientjes@google.com> - 2016-07-14 22:30 +0200
                Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-15 13:30 +0200
                Re: System freezes after OOM David Rientjes <rientjes@google.com> - 2016-07-15 23:30 +0200
                Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-15 23:50 +0200
                Re: System freezes after OOM David Rientjes <rientjes@google.com> - 2016-07-16 00:00 +0200
                Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-16 02:00 +0200
                Re: System freezes after OOM Johannes Weiner <hannes@cmpxchg.org> - 2016-07-18 17:20 +0200
                Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-14 17:30 +0200
                Re: System freezes after OOM David Rientjes <rientjes@google.com> - 2016-07-14 22:40 +0200
                Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-15 09:30 +0200
                Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-15 10:30 +0200
                Re: System freezes after OOM Mikulas Patocka <mpatocka@redhat.com> - 2016-07-15 14:10 +0200
                Re: System freezes after OOM David Rientjes <rientjes@google.com> - 2016-07-15 23:50 +0200
                Re: System freezes after OOM Michal Hocko <mhocko@kernel.org> - 2016-07-18 09:40 +0200
                Re: System freezes after OOM David Rientjes <rientjes@google.com> - 2016-07-18 23:10 +0200
        Re: System freezes after OOM David Rientjes <rientjes@google.com> - 2016-07-14 02:10 +0200

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