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From: js1304@gmail.com
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Michal Hocko <mhocko@kernel.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
	Mel Gorman <mgorman@techsingularity.net>,
	kernel-team@lge.com, Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: [PATCH v2 for v5.9] mm/page_alloc: handle a missing case for memalloc_nocma_{save/restore} APIs
Date: Mon, 28 Sep 2020 17:50:46 +0900	[thread overview]
Message-ID: <1601283046-15329-1-git-send-email-iamjoonsoo.kim@lge.com> (raw)

From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

memalloc_nocma_{save/restore} APIs can be used to skip page allocation
on CMA area, but, there is a missing case and the page on CMA area could
be allocated even if APIs are used. This patch handles this case to fix
the potential issue.

Missing case is an allocation from the pcplist. MIGRATE_MOVABLE pcplist
could have the pages on CMA area so we need to skip it if ALLOC_CMA isn't
specified.

Fixes: 8510e69c8efe (mm/page_alloc: fix memalloc_nocma_{save/restore} APIs)
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
 mm/page_alloc.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index fab5e97..104d2e1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3367,9 +3367,16 @@ struct page *rmqueue(struct zone *preferred_zone,
 	struct page *page;
 
 	if (likely(order == 0)) {
-		page = rmqueue_pcplist(preferred_zone, zone, gfp_flags,
+		/*
+		 * MIGRATE_MOVABLE pcplist could have the pages on CMA area and
+		 * we need to skip it when CMA area isn't allowed.
+		 */
+		if (!IS_ENABLED(CONFIG_CMA) || alloc_flags & ALLOC_CMA ||
+				migratetype != MIGRATE_MOVABLE) {
+			page = rmqueue_pcplist(preferred_zone, zone, gfp_flags,
 					migratetype, alloc_flags);
-		goto out;
+			goto out;
+		}
 	}
 
 	/*
@@ -3381,7 +3388,7 @@ struct page *rmqueue(struct zone *preferred_zone,
 
 	do {
 		page = NULL;
-		if (alloc_flags & ALLOC_HARDER) {
+		if (order > 0 && alloc_flags & ALLOC_HARDER) {
 			page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
 			if (page)
 				trace_mm_page_alloc_zone_locked(page, order, migratetype);
-- 
2.7.4


             reply	other threads:[~2020-09-28  8:51 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-28  8:50 js1304 [this message]
2020-09-28 23:52 ` [PATCH v2 for v5.9] mm/page_alloc: handle a missing case for memalloc_nocma_{save/restore} APIs Andrew Morton
2020-09-29  1:28   ` Joonsoo Kim
2020-09-29  4:50     ` Andrew Morton
2020-09-29  6:46       ` Joonsoo Kim
2020-09-29  8:08 ` Michal Hocko
2020-09-29  8:38   ` Joonsoo Kim
2020-09-29  9:53     ` Michal Hocko
2020-09-29  8:13 ` Vlastimil Babka

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