Re: [PATCH v2] mm, oom: Give __GFP_NOFAIL allocations access to memory reserves

[David Rientjes]

On Wed, 2 Dec 2015, Michal Hocko wrote:

> From: Michal Hocko <mhocko@xxxxxxxx>
> 
> __GFP_NOFAIL is a big hammer used to ensure that the allocation
> request can never fail. This is a strong requirement and as such
> it also deserves a special treatment when the system is OOM. The
> primary problem here is that the allocation request might have
> come with some locks held and the oom victim might be blocked
> on the same locks. This is basically an OOM deadlock situation.
> 
> This patch tries to reduce the risk of such a deadlocks by giving
> __GFP_NOFAIL allocations a special treatment and let them dive into
> memory reserves after oom killer invocation. This should help them
> to make a progress and release resources they are holding. The OOM
> victim should compensate for the reserves consumption.
> 
> Suggested-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>

Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
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