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

From: Johannes Weiner
Date: Wed Nov 11 2015 - 10:55:10 EST

On Wed, Nov 11, 2015 at 02:48:17PM +0100, mhocko@xxxxxxxxxx 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.
> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> Hi,
> this has been posted previously as a part of larger GFP_NOFS related
> patch set (
> but Andrea was asking basically the same thing at LSF early this year
> (I cannot seem to find it in any public archive though). I think the
> patch makes some sense on its own.

I sent this right after LSF based on Andrea's suggestion:
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