linux-kernel - [PATCH 3/4] mm, page_alloc: move might_sleep_if check to the allocator slowpath -revert

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Message-Id: <1461759885-17163-4-git-send-email-mgorman@techsingularity.net>
Date:	Wed, 27 Apr 2016 13:24:44 +0100
From:	Mel Gorman <mgorman@...hsingularity.net>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Vlastimil Babka <vbabka@...e.cz>,
	Jesper Dangaard Brouer <brouer@...hat.com>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Mel Gorman <mgorman@...hsingularity.net>
Subject: [PATCH 3/4] mm, page_alloc: move might_sleep_if check to the allocator slowpath -revert

Vlastimil Babka pointed out that a patch weakens a zone_reclaim test
which while "safe" defeats the purposes of the debugging check. As most
configurations eliminate this check anyway, I thought it was better to
simply revert the patch instead of adding a second check in zone_reclaim.

This is a revert of the mmotm patch
mm-page_alloc-move-might_sleep_if-check-to-the-allocator-slowpath.patch .

Suggested-by: Vlastimil Babka <vbabka@...e.cz>
Signed-off-by: Mel Gorman <mgorman@...hsingularity.net>
---
 mm/page_alloc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 45a36e98b9cb..599bd1a49384 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3606,8 +3606,6 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 		return NULL;
 	}
 
-	might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
-
 	/*
 	 * We also sanity check to catch abuse of atomic reserves being used by
 	 * callers that are not in atomic context.
@@ -3806,6 +3804,8 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 
 	lockdep_trace_alloc(gfp_mask);
 
+	might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
+
 	if (should_fail_alloc_page(gfp_mask, order))
 		return NULL;
 
-- 
2.6.4