From 57cbc87e03c2f473d8f0579186c078ee06f48f2c Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Thu, 13 Nov 2014 15:19:36 -0800 Subject: [PATCH] mm/debug-pagealloc: correct freepage accounting and order resetting One thing I did in this patch is fixing freepage accounting. If we clear guard page and link it onto isolate buddy list, we should not increase freepage count. This patch adds conditional branch to skip counting in this case. Without this patch, this overcounting happens frequently if guard order is set and CMA is used. Another thing fixed in this patch is the target to reset order. In __free_one_page(), we check the buddy page whether it is a guard page or not. And, if so, we should clear guard attribute on the buddy page and reset order of it to 0. But, current code resets original page's order rather than buddy one's. Maybe, this doesn't have any problem, because whole merged page's order will be re-assigned soon. But, it is better to correct code. Signed-off-by: Joonsoo Kim Acked-by: Vlastimil Babka Cc: Gioh Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 181dc593962b..616a2c956b4b 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -583,9 +583,11 @@ static inline void __free_one_page(struct page *page, */ if (page_is_guard(buddy)) { clear_page_guard_flag(buddy); - set_page_private(page, 0); - __mod_zone_freepage_state(zone, 1 << order, - migratetype); + set_page_private(buddy, 0); + if (!is_migrate_isolate(migratetype)) { + __mod_zone_freepage_state(zone, 1 << order, + migratetype); + } } else { list_del(&buddy->lru); zone->free_area[order].nr_free--; -- 2.20.1