Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1447964

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

Show all headers | View raw

On Thu, Jul 21, 2016 at 04:53:10PM +0200, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> Date: Thu, 21 Jul 2016 16:40:59 +0200
> Subject: [PATCH] Revert "mm, mempool: only set __GFP_NOMEMALLOC if there are
>  free elements"
> 
> This reverts commit f9054c70d28bc214b2857cf8db8269f4f45a5e23.
> 
> There has been a report about OOM killer invoked when swapping out to
> a dm-crypt device. The primary reason seems to be that the swapout
> out IO managed to completely deplete memory reserves. Ondrej was

-out

> able to bisect and explained the issue by pointing to f9054c70d28b
> ("mm, mempool: only set __GFP_NOMEMALLOC if there are free elements").
> 
> The reason is that the swapout path is not throttled properly because
> the md-raid layer needs to allocate from the generic_make_request path
> which means it allocates from the PF_MEMALLOC context. dm layer uses
> mempool_alloc in order to guarantee a forward progress which used to
> inhibit access to memory reserves when using page allocator. This has
> changed by f9054c70d28b ("mm, mempool: only set __GFP_NOMEMALLOC if
> there are free elements") which has dropped the __GFP_NOMEMALLOC
> protection when the memory pool is depleted.
> 
> If we are running out of memory and the only way forward to free memory
> is to perform swapout we just keep consuming memory reserves rather than
> throttling the mempool allocations and allowing the pending IO to
> complete up to a moment when the memory is depleted completely and there
> is no way forward but invoking the OOM killer. This is less than
> optimal.
> 
> The original intention of f9054c70d28b was to help with the OOM
> situations where the oom victim depends on mempool allocation to make a
> forward progress. David has mentioned the following backtrace:
> 
> schedule
> schedule_timeout
> io_schedule_timeout
> mempool_alloc
> __split_and_process_bio
> dm_request
> generic_make_request
> submit_bio
> mpage_readpages
> ext4_readpages
> __do_page_cache_readahead
> ra_submit
> filemap_fault
> handle_mm_fault
> __do_page_fault
> do_page_fault
> page_fault
> 
> We do not know more about why the mempool is depleted without being
> replenished in time, though. In any case the dm layer shouldn't depend
> on any allocations outside of the dedicated pools so a forward progress
> should be guaranteed. If this is not the case then the dm should be
> fixed rather than papering over the problem and postponing it to later
> by accessing more memory reserves.
> 
> mempools are a mechanism to maintain dedicated memory reserves to guaratee
> forward progress. Allowing them an unbounded access to the page allocator
> memory reserves is going against the whole purpose of this mechanism.
> 
> Bisected-by: Ondrej Kozina <okozina@redhat.com>
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>

Thanks Michal

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

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