https://github.com/torvalds/linux
Revision 84235de394d9775bfaa7fa9762a59d91fef0c1fc authored by Johannes Weiner on 16 October 2013, 20:47:00 UTC, committed by Linus Torvalds on 17 October 2013, 04:35:53 UTC
Buffer allocation has a very crude indefinite loop around waking the flusher threads and performing global NOFS direct reclaim because it can not handle allocation failures. The most immediate problem with this is that the allocation may fail due to a memory cgroup limit, where flushers + direct reclaim might not make any progress towards resolving the situation at all. Because unlike the global case, a memory cgroup may not have any cache at all, only anonymous pages but no swap. This situation will lead to a reclaim livelock with insane IO from waking the flushers and thrashing unrelated filesystem cache in a tight loop. Use __GFP_NOFAIL allocations for buffers for now. This makes sure that any looping happens in the page allocator, which knows how to orchestrate kswapd, direct reclaim, and the flushers sensibly. It also allows memory cgroups to detect allocations that can't handle failure and will allow them to ultimately bypass the limit if reclaim can not make progress. Reported-by: azurIt <azurit@pobox.sk> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Tip revision: 84235de394d9775bfaa7fa9762a59d91fef0c1fc authored by Johannes Weiner on 16 October 2013, 20:47:00 UTC
fs: buffer: move allocation failure loop into the allocator
fs: buffer: move allocation failure loop into the allocator
Tip revision: 84235de
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lib | ||
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net | ||
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