Subject: [merged] mm-__rmqueue_fallback-should-respect-pageblock-type.patch removed from -mm tree To: kosaki.motohiro@xxxxxxxxxxxxxx,mgorman@xxxxxxx,mina86@xxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Wed, 13 Nov 2013 12:39:20 -0800 The patch titled Subject: mm: __rmqueue_fallback() should respect pageblock type has been removed from the -mm tree. Its filename was mm-__rmqueue_fallback-should-respect-pageblock-type.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Subject: mm: __rmqueue_fallback() should respect pageblock type When __rmqueue_fallback() doesn't find a free block with the required size it splits a larger page and puts the rest of the page onto the free list. But it has one serious mistake. When putting back, __rmqueue_fallback() always use start_migratetype if type is not CMA. However, __rmqueue_fallback() is only called when all of the start_migratetype queue is empty. That said, __rmqueue_fallback always puts back memory to the wrong queue except try_to_steal_freepages() changed pageblock type (i.e. requested size is smaller than half of page block). The end result is that the antifragmentation framework increases fragmenation instead of decreasing it. Mel's original anti fragmentation does the right thing. But commit 47118af076 ("mm: mmzone: MIGRATE_CMA migration type added") broke it. This patch restores sane and old behavior. And also it remvoe an incorrect comment which introduced at commit fef903efcf (mm/page_alloc.c: restructure free-page stealing code and fix a bug). Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Michal Nazarewicz <mina86@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_alloc.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff -puN mm/page_alloc.c~mm-__rmqueue_fallback-should-respect-pageblock-type mm/page_alloc.c --- a/mm/page_alloc.c~mm-__rmqueue_fallback-should-respect-pageblock-type +++ a/mm/page_alloc.c @@ -1027,6 +1027,10 @@ static int try_to_steal_freepages(struct { int current_order = page_order(page); + /* + * When borrowing from MIGRATE_CMA, we need to release the excess + * buddy pages to CMA itself. + */ if (is_migrate_cma(fallback_type)) return fallback_type; @@ -1091,17 +1095,8 @@ __rmqueue_fallback(struct zone *zone, in list_del(&page->lru); rmv_page_order(page); - /* - * Borrow the excess buddy pages as well, irrespective - * of whether we stole freepages, or took ownership of - * the pageblock or not. - * - * Exception: When borrowing from MIGRATE_CMA, release - * the excess buddy pages to CMA itself. - */ expand(zone, page, order, current_order, area, - is_migrate_cma(migratetype) - ? migratetype : start_migratetype); + new_type); trace_mm_page_alloc_extfrag(page, order, current_order, start_migratetype, migratetype, new_type); _ Patches currently in -mm which might be from kosaki.motohiro@xxxxxxxxxxxxxx are origin.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html