linux-kernel - [PATCH 2/3] CMA: Fix the issue that nr_try_movable just count MIGRATE

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Date:	Thu, 25 Dec 2014 17:43:27 +0800
From:	Hui Zhu <zhuhui@...omi.com>
To:	<m.szyprowski@...sung.com>, <mina86@...a86.com>,
	<akpm@...ux-foundation.org>, <iamjoonsoo.kim@....com>,
	<aneesh.kumar@...ux.vnet.ibm.com>, <pintu.k@...sung.com>,
	<weijie.yang@...sung.com>, <mgorman@...e.de>, <hannes@...xchg.org>,
	<riel@...hat.com>, <vbabka@...e.cz>,
	<laurent.pinchart+renesas@...asonboard.com>, <rientjes@...gle.com>,
	<sasha.levin@...cle.com>, <liuweixing@...omi.com>,
	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>
CC:	<teawater@...il.com>, Hui Zhu <zhuhui@...omi.com>
Subject: [PATCH 2/3] CMA: Fix the issue that nr_try_movable just count MIGRATE_MOVABLE memory

One of my plotform that use Joonsoo's CMA patch [1] has a device that
will alloc a lot of MIGRATE_UNMOVABLE memory when it works in a zone.
When this device works, the memory status of this zone is not OK.  Most of
CMA is not allocated but most normal memory is allocated.
This issue is because in __rmqueue:
	if (IS_ENABLED(CONFIG_CMA) &&
		migratetype == MIGRATE_MOVABLE && zone->managed_cma_pages)
		page = __rmqueue_cma(zone, order);
Just allocated MIGRATE_MOVABLE will be record in nr_try_movable in function
__rmqueue_cma but not the others.  This device allocated a lot of
MIGRATE_UNMOVABLE memory affect the behavior of this zone memory allocation.

This patch change __rmqueue to let nr_try_movable record all the memory
allocation of normal memory.

[1] https://lkml.org/lkml/2014/5/28/64

Signed-off-by: Hui Zhu <zhuhui@...omi.com>
Signed-off-by: Weixing Liu <liuweixing@...omi.com>
---
 mm/page_alloc.c | 41 ++++++++++++++++++++---------------------
 1 file changed, 20 insertions(+), 21 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a8d9f03..a5bbc38 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1301,28 +1301,23 @@ static struct page *__rmqueue_cma(struct zone *zone, unsigned int order)
 {
 	struct page *page;
 
-	if (zone->nr_try_movable > 0)
-		goto alloc_movable;
+	if (zone->nr_try_cma <= 0) {
+		/* Reset counter */
+		zone->nr_try_movable = zone->max_try_movable;
+		zone->nr_try_cma = zone->max_try_cma;
 
-	if (zone->nr_try_cma > 0) {
-		/* Okay. Now, we can try to allocate the page from cma region */
-		zone->nr_try_cma -= 1 << order;
-		page = __rmqueue_smallest(zone, order, MIGRATE_CMA);
-
-		/* CMA pages can vanish through CMA allocation */
-		if (unlikely(!page && order == 0))
-			zone->nr_try_cma = 0;
-
-		return page;
+		return NULL;
 	}
 
-	/* Reset counter */
-	zone->nr_try_movable = zone->max_try_movable;
-	zone->nr_try_cma = zone->max_try_cma;
+	/* Okay. Now, we can try to allocate the page from cma region */
+	zone->nr_try_cma -= 1 << order;
+	page = __rmqueue_smallest(zone, order, MIGRATE_CMA);
 
-alloc_movable:
-	zone->nr_try_movable -= 1 << order;
-	return NULL;
+	/* CMA pages can vanish through CMA allocation */
+	if (unlikely(!page && order == 0))
+		zone->nr_try_cma = 0;
+
+	return page;
 }
 #endif
 
@@ -1335,9 +1330,13 @@ static struct page *__rmqueue(struct zone *zone, unsigned int order,
 {
 	struct page *page = NULL;
 
-	if (IS_ENABLED(CONFIG_CMA) &&
-		migratetype == MIGRATE_MOVABLE && zone->managed_cma_pages)
-		page = __rmqueue_cma(zone, order);
+	if (IS_ENABLED(CONFIG_CMA) && zone->managed_cma_pages) {
+		if (migratetype == MIGRATE_MOVABLE
+		    && zone->nr_try_movable <= 0)
+			page = __rmqueue_cma(zone, order);
+		else
+			zone->nr_try_movable -= 1 << order;
+	}
 
 retry_reserve:
 	if (!page)
-- 
1.9.1

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