Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the reclaim path

From	David Rientjes <rientjes@google.com>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the reclaim path
Date	2016-07-19 04:10 +0200
Message-ID	<rWsDT-68O-5@gated-at.bofh.it> (permalink)
References	<rWcfL-3Nz-13@gated-at.bofh.it> <rWcpr-3TV-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Mon, 18 Jul 2016, Michal Hocko wrote:

> David Rientjes was objecting that such an approach wouldn't help if the
> oom victim was blocked on a lock held by process doing mempool_alloc. This
> is very similar to other oom deadlock situations and we have oom_reaper
> to deal with them so it is reasonable to rely on the same mechanism
> rather inventing a different one which has negative side effects.
> 

Right, this causes oom livelock as described in the aforementioned thread: 
the oom victim is waiting on a mutex that is held by a thread doing 
mempool_alloc().  The oom reaper is not guaranteed to free any memory, so 
nothing on the system can allocate memory from the page allocator.

I think the better solution here is to allow mempool_alloc() users to set 
__GFP_NOMEMALLOC if they are in a context which allows them to deplete 
memory reserves.

Thread

[RFC PATCH 0/2] mempool vs. page allocator interaction Michal Hocko <mhocko@kernel.org> - 2016-07-18 10:40 +0200
  [RFC PATCH 1/2] mempool: do not consume memory reserves from the reclaim path Michal Hocko <mhocko@kernel.org> - 2016-07-18 10:50 +0200
    [RFC PATCH 2/2] mm, mempool: do not throttle PF_LESS_THROTTLE tasks Michal Hocko <mhocko@kernel.org> - 2016-07-18 10:50 +0200
      Re: [RFC PATCH 2/2] mm, mempool: do not throttle PF_LESS_THROTTLE  tasks Mikulas Patocka <mpatocka@redhat.com> - 2016-07-20 00:00 +0200
      Re: [RFC PATCH 2/2] mm, mempool: do not throttle PF_LESS_THROTTLE tasks NeilBrown <neilb@suse.de> - 2016-07-22 10:50 +0200
        Re: [RFC PATCH 2/2] mm, mempool: do not throttle PF_LESS_THROTTLE tasks NeilBrown <neilb@suse.com> - 2016-07-22 11:10 +0200
        Re: [RFC PATCH 2/2] mm, mempool: do not throttle PF_LESS_THROTTLE  tasks Michal Hocko <mhocko@kernel.org> - 2016-07-22 11:20 +0200
          Re: [RFC PATCH 2/2] mm, mempool: do not throttle PF_LESS_THROTTLE tasks NeilBrown <neilb@suse.com> - 2016-07-23 02:20 +0200
            Re: [RFC PATCH 2/2] mm, mempool: do not throttle PF_LESS_THROTTLE  tasks Michal Hocko <mhocko@kernel.org> - 2016-07-25 10:40 +0200
              Re: [RFC PATCH 2/2] mm, mempool: do not throttle PF_LESS_THROTTLE  tasks Michal Hocko <mhocko@kernel.org> - 2016-07-25 21:30 +0200
    Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from  the reclaim path David Rientjes <rientjes@google.com> - 2016-07-19 04:10 +0200
      Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the  reclaim path Michal Hocko <mhocko@kernel.org> - 2016-07-19 09:50 +0200
    Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the  reclaim path Johannes Weiner <hannes@cmpxchg.org> - 2016-07-19 16:00 +0200
      Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the  reclaim path Michal Hocko <mhocko@kernel.org> - 2016-07-19 16:30 +0200
        Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from  the reclaim path Mikulas Patocka <mpatocka@redhat.com> - 2016-07-20 00:10 +0200
      Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from  the reclaim path David Rientjes <rientjes@google.com> - 2016-07-19 22:50 +0200
        Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the  reclaim path Michal Hocko <mhocko@kernel.org> - 2016-07-20 10:20 +0200
          Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from  the reclaim path David Rientjes <rientjes@google.com> - 2016-07-20 23:10 +0200
            Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the  reclaim path Michal Hocko <mhocko@kernel.org> - 2016-07-21 11:00 +0200
              Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the  reclaim path Johannes Weiner <hannes@cmpxchg.org> - 2016-07-21 14:20 +0200
                Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the  reclaim path Michal Hocko <mhocko@kernel.org> - 2016-07-21 17:00 +0200
                Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the  reclaim path Johannes Weiner <hannes@cmpxchg.org> - 2016-07-21 17:30 +0200
                Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the reclaim path NeilBrown <neilb@suse.com> - 2016-07-22 03:50 +0200
                Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the  reclaim path Michal Hocko <mhocko@kernel.org> - 2016-07-22 08:40 +0200
                Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the  reclaim path Vlastimil Babka <vbabka@suse.cz> - 2016-07-22 14:30 +0200
                Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from  the reclaim path Andrew Morton <akpm@linux-foundation.org> - 2016-07-22 21:50 +0200
                Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the  reclaim path Vlastimil Babka <vbabka@suse.cz> - 2016-07-23 21:00 +0200
    Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from  the reclaim path Mikulas Patocka <mpatocka@redhat.com> - 2016-07-20 00:00 +0200
      Re: [RFC PATCH 1/2] mempool: do not consume memory reserves from the  reclaim path Michal Hocko <mhocko@kernel.org> - 2016-07-20 08:50 +0200

csiph-web