linux-kernel - [PATCH] mm: cma: allocate pages from CMA if NR_FREE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-id: <1352710782-25425-1-git-send-email-m.szyprowski@samsung.com>
Date:	Mon, 12 Nov 2012 09:59:42 +0100
From:	Marek Szyprowski <m.szyprowski@...sung.com>
To:	linux-mm@...ck.org, linaro-mm-sig@...ts.linaro.org,
	linux-kernel@...r.kernel.org
Cc:	Marek Szyprowski <m.szyprowski@...sung.com>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mel@....ul.ie>,
	Michal Nazarewicz <mina86@...a86.com>,
	Minchan Kim <minchan@...nel.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: [PATCH] mm: cma: allocate pages from CMA if NR_FREE_PAGES approaches
 low water mark

It has been observed that system tends to keep a lot of CMA free pages
even in very high memory pressure use cases. The CMA fallback for movable
pages is used very rarely, only when system is completely pruned from
MOVABLE pages, what usually means that the out-of-memory even will be
triggered very soon. To avoid such situation and make better use of CMA
pages, a heuristics is introduced which turns on CMA fallback for movable
pages when the real number of free pages (excluding CMA free pages)
approaches low water mark.

Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
Reviewed-by: Kyungmin Park <kyungmin.park@...sung.com>
CC: Michal Nazarewicz <mina86@...a86.com>
---
 mm/page_alloc.c |    9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index fcb9719..90b51f3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1076,6 +1076,15 @@ static struct page *__rmqueue(struct zone *zone, unsigned int order,
 {
 	struct page *page;
 
+#ifdef CONFIG_CMA
+	unsigned long nr_free = zone_page_state(zone, NR_FREE_PAGES);
+	unsigned long nr_cma_free = zone_page_state(zone, NR_FREE_CMA_PAGES);
+
+	if (migratetype == MIGRATE_MOVABLE && nr_cma_free &&
+	    nr_free - nr_cma_free < 2 * low_wmark_pages(zone))
+		migratetype = MIGRATE_CMA;
+#endif /* CONFIG_CMA */
+
 retry_reserve:
 	page = __rmqueue_smallest(zone, order, migratetype);
 
-- 
1.7.9.5

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/