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Reply-To: "Hillf Danton" <hillf.zj@alibaba-inc.com>
From: "Hillf Danton" <hillf.zj@alibaba-inc.com>
References: <20161220134904.21023-1-mhocko@kernel.org> <20161220134904.21023-3-mhocko@kernel.org>
In-Reply-To: <20161220134904.21023-3-mhocko@kernel.org>
Subject: Re: [PATCH 2/3] mm, oom: do not enfore OOM killer for __GFP_NOFAIL automatically
Date: Fri, 20 Jan 2017 16:33:36 +0800
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Sender: owner-linux-mm@kvack.org
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To: 'Michal Hocko' <mhocko@kernel.org>, 'Andrew Morton' <akpm@linux-foundation.org>
Cc: 'Johannes Weiner' <hannes@cmpxchg.org>, 'Tetsuo Handa' <penguin-kernel@I-love.SAKURA.ne.jp>, 'David Rientjes' <rientjes@google.com>, 'Mel Gorman' <mgorman@suse.de>, linux-mm@kvack.org, 'LKML' <linux-kernel@vger.kernel.org>, 'Michal Hocko' <mhocko@suse.com>


On Tuesday, December 20, 2016 9:49 PM Michal Hocko wrote: 
> 
> @@ -1013,7 +1013,7 @@ bool out_of_memory(struct oom_control *oc)
>  	 * make sure exclude 0 mask - all other users should have at least
>  	 * ___GFP_DIRECT_RECLAIM to get here.
>  	 */
> -	if (oc->gfp_mask && !(oc->gfp_mask & (__GFP_FS|__GFP_NOFAIL)))
> +	if (oc->gfp_mask && !(oc->gfp_mask & __GFP_FS))
>  		return true;
> 
As to GFP_NOFS|__GFP_NOFAIL request, can we check gfp mask
one bit after another?

	if (oc->gfp_mask) {
		if (!(oc->gfp_mask & __GFP_FS))
			return false;

		/* No service for request that can handle fail result itself */
		if (!(oc->gfp_mask & __GFP_NOFAIL))
			return false;
	}

thanks
Hillf


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