Messages in this thread | | | Date | Wed, 13 Jul 2016 17:01:37 -0700 (PDT) | From | David Rientjes <> | Subject | Re: System freezes after OOM |
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On Wed, 13 Jul 2016, Tetsuo Handa wrote:
> I wonder whether commit f9054c70d28bc214 ("mm, mempool: only set > __GFP_NOMEMALLOC if there are free elements") is doing correct thing. > It says > > If an oom killed thread calls mempool_alloc(), it is possible that it'll > loop forever if there are no elements on the freelist since > __GFP_NOMEMALLOC prevents it from accessing needed memory reserves in > oom conditions. > > but we can allow mempool_alloc(__GFP_NOMEMALLOC) requests to access > memory reserves via below change, can't we? The purpose of allowing > ALLOC_NO_WATERMARKS via TIF_MEMDIE is to make sure current allocation > request does not to loop forever inside the page allocator, isn't it?
This would defeat the purpose of __GFP_NOMEMALLOC for oom killed threads, so you'd need to demonstrate that isn't a problem for the current users and then change the semantics of the gfp flag.
> Why we need to allow mempool_alloc(__GFP_NOMEMALLOC) requests to use > ALLOC_NO_WATERMARKS when TIF_MEMDIE is not set? >
mempool_alloc(__GFP_NOMEMALLOC) is forbidden.
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