From mboxrd@z Thu Jan 1 00:00:00 1970 From: Miles Chen Subject: [PATCH] mm/page_owner: fix incorrect looping in __set_page_owner_handle() Date: Fri, 4 Oct 2019 15:37:55 +0800 Message-ID: <20191004073755.3228-1-miles.chen@mediatek.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Sender: linux-kernel-owner@vger.kernel.org To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com, Miles Chen , Vlastimil Babka , Michal Hocko List-Id: linux-mediatek@lists.infradead.org In __set_page_owner_handle(), we should loop over page [0...(1 << order) - 1] and setup their page_owner structures. Currently, __set_page_owner_handle() update page_ext at the end of the loop, sets the page_owner of (page + 0) twice and misses the page_owner of (page + (1 << order) - 1). Fix it by updating the page_ext at the start of the loop. In i == 0 case: for (i = 0; i < (1 << order); i++) { page_owner = get_page_owner(page_ext); <- page_ext belongs to page + 0 ... page_ext = lookup_page_ext(page + i); <- lookup_page_ext(page + 0) } Cc: Andrew Morton Cc: Vlastimil Babka Cc: Michal Hocko Signed-off-by: Miles Chen Fixes: 7e2f2a0cd17c ("mm, page_owner: record page owner for each subpage") --- mm/page_owner.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index dee931184788..110c3e1987f2 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -178,6 +178,7 @@ static inline void __set_page_owner_handle(struct page *page, int i; for (i = 0; i < (1 << order); i++) { + page_ext = lookup_page_ext(page + i); page_owner = get_page_owner(page_ext); page_owner->handle = handle; page_owner->order = order; @@ -185,8 +186,6 @@ static inline void __set_page_owner_handle(struct page *page, page_owner->last_migrate_reason = -1; __set_bit(PAGE_EXT_OWNER, &page_ext->flags); __set_bit(PAGE_EXT_OWNER_ACTIVE, &page_ext->flags); - - page_ext = lookup_page_ext(page + i); } } -- 2.18.0