linux-kernel - Re: [PATCH -v2] mm, oom: do not fail __GFP_NOFAIL allocation if oom killer is disbaled

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Date:	Wed, 25 Feb 2015 12:41:07 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Michal Hocko <mhocko@...e.cz>
cc:	Johannes Weiner <hannes@...xchg.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"\\\"Rafael J. Wysocki\\\"" <rjw@...ysocki.net>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -v2] mm, oom: do not fail __GFP_NOFAIL allocation if oom
 killer is disbaled

On Wed, 25 Feb 2015, Michal Hocko wrote:

> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 2d224bbdf8e8..c2ff40a30003 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2363,7 +2363,8 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
>  			goto out;
>  	}
>  	/* Exhausted what can be done so it's blamo time */
> -	if (out_of_memory(ac->zonelist, gfp_mask, order, ac->nodemask, false))
> +	if (out_of_memory(ac->zonelist, gfp_mask, order, ac->nodemask, false)
> +			|| WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL))
>  		*did_some_progress = 1;
>  out:
>  	oom_zonelist_unlock(ac->zonelist, gfp_mask);

Eek, not sure we actually need to play any games with did_some_progress, 
it might be clearer just to do this

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2760,7 +2760,7 @@ retry:
 							&did_some_progress);
 			if (page)
 				goto got_pg;
-			if (!did_some_progress)
+			if (!did_some_progress && !(gfp_mask & __GFP_NOFAIL))
 				goto nopage;
 		}
 		/* Wait for some write requests to complete then retry */

Either way you decide, feel free to add my

Acked-by: David Rientjes <rientjes@...ogle.com>
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