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

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Date:	Fri, 17 Jul 2009 13:41:04 +0100 (BST)
From:	Hugh Dickins <hugh.dickins@...cali.co.uk>
To:	David Rientjes <rientjes@...gle.com>
cc:	Mel Gorman <mel@....ul.ie>,
	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 Fri, 17 Jul 2009, David Rientjes wrote:
> On Fri, 17 Jul 2009, Mel Gorman wrote:
> 
> > Ok, lets go with this patch then. Thanks
> > 
> 
> Ok, thanks, I'll add that as your acked-by and I'll write a formal patch 
> description for it.
> 
> 
> mm: avoid endless looping for oom killed tasks
> 
> If a task is oom killed and still cannot find memory when trying with no 
> watermarks, it's better to fail the allocation attempt than to loop 
> endlessly.  Direct reclaim has already failed and the oom killer will be a 
> no-op since current has yet to die, so there is no other alternative for 
> allocations that are not __GFP_NOFAIL.
> 
> Acked-by: Mel Gorman <mel@....ul.ie>
> Signed-off-by: David Rientjes <rientjes@...gle.com>

This works much better for me than earlier variants (I'm needing to worry
about OOM when KSM has a lot of pages to break COW on; but a large mlock
is a good test) - thanks.

Acked-by: Hugh Dickins <hugh.dickins@...cali.co.uk>

> ---
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1789,6 +1789,10 @@ rebalance:
>  	if (p->flags & PF_MEMALLOC)
>  		goto nopage;
>  
> +	/* Avoid allocations with no watermarks from looping endlessly */
> +	if (test_thread_flag(TIF_MEMDIE) && !(gfp_mask & __GFP_NOFAIL))
> +		goto nopage;
> +
>  	/* Try direct reclaim and then allocating */
>  	page = __alloc_pages_direct_reclaim(gfp_mask, order,
>  					zonelist, high_zoneidx,
--
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