linux-kernel - [PATCH V2] mm, page_alloc: reserve pageblocks for high-order atomic allocations on demand -fix

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Date:	Tue, 13 Oct 2015 09:42:24 +0800
From:	yalin wang <yalin.wang2010@...il.com>
To:	akpm@...ux-foundation.org, vbabka@...e.cz,
	mgorman@...hsingularity.net, mhocko@...e.com, rientjes@...gle.com,
	js1304@...il.com, kirill.shutemov@...ux.intel.com,
	hannes@...xchg.org, alexander.h.duyck@...hat.com,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:	yalin wang <yalin.wang2010@...il.com>
Subject: [PATCH V2] mm, page_alloc: reserve pageblocks for high-order atomic allocations on demand -fix

There is a redundant check and a memory leak introduced by a patch in
mmotm. This patch removes an unlikely(order) check as we are sure order
is not zero at the time. It also checks if a page is already allocated
to avoid a memory leak.

This is a fix to the mmotm patch
mm-page_alloc-reserve-pageblocks-for-high-order-atomic-allocations-on-demand.patch

Signed-off-by: yalin wang <yalin.wang2010@...il.com>
Acked-by: Mel Gorman <mgorman@...hsingularity.net>
---
 mm/page_alloc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0d6f540..043b691 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2241,13 +2241,13 @@ struct page *buffered_rmqueue(struct zone *preferred_zone,
 		spin_lock_irqsave(&zone->lock, flags);
 
 		page = NULL;
-		if (unlikely(order) && (alloc_flags & ALLOC_HARDER)) {
+		if (alloc_flags & ALLOC_HARDER) {
 			page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
 			if (page)
 				trace_mm_page_alloc_zone_locked(page, order, migratetype);
 		}
-
-		page = __rmqueue(zone, order, migratetype, gfp_flags);
+		if (!page)
+			page = __rmqueue(zone, order, migratetype, gfp_flags);
 		spin_unlock(&zone->lock);
 		if (!page)
 			goto failed;
-- 
1.9.1

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