linux-kernel - Re: [PATCH] page-allocator: Ensure that processes that have been OOM killed exit the page allocator (resend)

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Message-ID: <alpine.DEB.2.00.0907151326350.22582@chino.kir.corp.google.com>
Date:	Wed, 15 Jul 2009 13:29:33 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Mel Gorman <mel@....ul.ie>
cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Nick Piggin <npiggin@...e.de>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [PATCH] page-allocator: Ensure that processes that have been
 OOM killed exit the page allocator (resend)

On Wed, 15 Jul 2009, Mel Gorman wrote:

> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index f8902e7..5c98d02 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1547,6 +1547,14 @@ should_alloc_retry(gfp_t gfp_mask, unsigned int order,
>  	if (gfp_mask & __GFP_NORETRY)
>  		return 0;
>  
> +	/* Do not loop if OOM-killed unless __GFP_NOFAIL is specified */
> +	if (test_thread_flag(TIF_MEMDIE)) {
> +		if (gfp_mask & __GFP_NOFAIL)
> +			WARN(1, "Potential infinite loop with __GFP_NOFAIL");
> +		else
> +			return 0;
> +	}
> +
>  	/*
>  	 * In this implementation, order <= PAGE_ALLOC_COSTLY_ORDER
>  	 * means __GFP_NOFAIL, but that may not be true in other
> 

This only works for GFP_ATOMIC since the next iteration of the page 
allocator will (probably) fail reclaim and simply invoke the oom killer 
again, which will notice current has TIF_MEMDIE set and choose to do 
nothing, at which time the allocator simply loops again.
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