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authorJoonsoo Kim <iamjoonsoo.kim@lge.com>2015-04-14 15:45:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-14 16:49:01 -0700
commitdc67647b78b92d9497f01fab95ac6764ed886b40 (patch)
treed8bfeadafe4a1f228547c455aef00edf95399135 /mm/page_alloc.c
parent30467e0b3be83c286d60039f8267dd421128ca74 (diff)
downloadop-kernel-dev-dc67647b78b92d9497f01fab95ac6764ed886b40.zip
op-kernel-dev-dc67647b78b92d9497f01fab95ac6764ed886b40.tar.gz
mm/cma: change fallback behaviour for CMA freepage
Freepage with MIGRATE_CMA can be used only for MIGRATE_MOVABLE and they should not be expanded to other migratetype buddy list to protect them from unmovable/reclaimable allocation. Implementing these requirements in __rmqueue_fallback(), that is, finding largest possible block of freepage has bad effect that high order freepage with MIGRATE_CMA are broken continually although there are suitable order CMA freepage. Reason is that they are not be expanded to other migratetype buddy list and next __rmqueue_fallback() invocation try to finds another largest block of freepage and break it again. So, MIGRATE_CMA fallback should be handled separately. This patch introduces __rmqueue_cma_fallback(), that just wrapper of __rmqueue_smallest() and call it before __rmqueue_fallback() if migratetype == MIGRATE_MOVABLE. This results in unintended behaviour change that MIGRATE_CMA freepage is always used first rather than other migratetype as movable allocation's fallback. But, as already mentioned above, MIGRATE_CMA can be used only for MIGRATE_MOVABLE, so it is better to use MIGRATE_CMA freepage first as much as possible. Otherwise, we needlessly take up precious freepages with other migratetype and increase chance of fragmentation. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
-rw-r--r--mm/page_alloc.c36
1 files changed, 19 insertions, 17 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 40e2942..9ca6267 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1032,11 +1032,9 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
static int fallbacks[MIGRATE_TYPES][4] = {
[MIGRATE_UNMOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE, MIGRATE_RESERVE },
[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE, MIGRATE_MOVABLE, MIGRATE_RESERVE },
+ [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_RESERVE },
#ifdef CONFIG_CMA
- [MIGRATE_MOVABLE] = { MIGRATE_CMA, MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_RESERVE },
[MIGRATE_CMA] = { MIGRATE_RESERVE }, /* Never used */
-#else
- [MIGRATE_MOVABLE] = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_RESERVE },
#endif
[MIGRATE_RESERVE] = { MIGRATE_RESERVE }, /* Never used */
#ifdef CONFIG_MEMORY_ISOLATION
@@ -1044,6 +1042,17 @@ static int fallbacks[MIGRATE_TYPES][4] = {
#endif
};
+#ifdef CONFIG_CMA
+static struct page *__rmqueue_cma_fallback(struct zone *zone,
+ unsigned int order)
+{
+ return __rmqueue_smallest(zone, order, MIGRATE_CMA);
+}
+#else
+static inline struct page *__rmqueue_cma_fallback(struct zone *zone,
+ unsigned int order) { return NULL; }
+#endif
+
/*
* Move the free pages in a range to the free lists of the requested type.
* Note that start_page and end_pages are not aligned on a pageblock
@@ -1195,19 +1204,8 @@ __rmqueue_fallback(struct zone *zone, unsigned int order, int start_migratetype)
struct page, lru);
area->nr_free--;
- if (!is_migrate_cma(migratetype)) {
- try_to_steal_freepages(zone, page,
- start_migratetype,
- migratetype);
- } else {
- /*
- * When borrowing from MIGRATE_CMA, we need to
- * release the excess buddy pages to CMA
- * itself, and we do not try to steal extra
- * free pages.
- */
- buddy_type = migratetype;
- }
+ try_to_steal_freepages(zone, page, start_migratetype,
+ migratetype);
/* Remove the page from the freelists */
list_del(&page->lru);
@@ -1249,7 +1247,11 @@ retry_reserve:
page = __rmqueue_smallest(zone, order, migratetype);
if (unlikely(!page) && migratetype != MIGRATE_RESERVE) {
- page = __rmqueue_fallback(zone, order, migratetype);
+ if (migratetype == MIGRATE_MOVABLE)
+ page = __rmqueue_cma_fallback(zone, order);
+
+ if (!page)
+ page = __rmqueue_fallback(zone, order, migratetype);
/*
* Use MIGRATE_RESERVE rather than fail an allocation. goto
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