From e34e744f70a68f8f16f945a286802898c56a8b5a Mon Sep 17 00:00:00 2001 From: Yang Shi Date: Fri, 3 Jun 2016 14:55:38 -0700 Subject: mm: check the return value of lookup_page_ext for all call sites commit f86e4271978bd93db466d6a95dad4b0fdcdb04f6 upstream. Per the discussion with Joonsoo Kim [1], we need check the return value of lookup_page_ext() for all call sites since it might return NULL in some cases, although it is unlikely, i.e. memory hotplug. Tested with ltp with "page_owner=0". [1] http://lkml.kernel.org/r/20160519002809.GA10245@js1304-P5Q-DELUXE [akpm@linux-foundation.org: fix build-breaking typos] [arnd@arndb.de: fix build problems from lookup_page_ext] Link: http://lkml.kernel.org/r/6285269.2CksypHdYp@wuerfel [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1464023768-31025-1-git-send-email-yang.shi@linaro.org Signed-off-by: Yang Shi Signed-off-by: Arnd Bergmann Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Michal Hocko Signed-off-by: Greg Kroah-Hartman --- mm/debug-pagealloc.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'mm/debug-pagealloc.c') diff --git a/mm/debug-pagealloc.c b/mm/debug-pagealloc.c index 5bf5906ce13b..fe1c61f7cf26 100644 --- a/mm/debug-pagealloc.c +++ b/mm/debug-pagealloc.c @@ -34,6 +34,8 @@ static inline void set_page_poison(struct page *page) struct page_ext *page_ext; page_ext = lookup_page_ext(page); + if (page_ext) + return; __set_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags); } @@ -42,6 +44,8 @@ static inline void clear_page_poison(struct page *page) struct page_ext *page_ext; page_ext = lookup_page_ext(page); + if (page_ext) + return; __clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags); } @@ -50,6 +54,8 @@ static inline bool page_poison(struct page *page) struct page_ext *page_ext; page_ext = lookup_page_ext(page); + if (page_ext) + return false; return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags); } -- cgit v1.2.3