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authorYang Shi <yang.shi@linaro.org>2016-06-03 21:55:38 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2016-06-03 22:06:22 (GMT)
commitf86e4271978bd93db466d6a95dad4b0fdcdb04f6 (patch)
tree26ef29934495da598a11c3a177d0294a71c5eae8 /mm/page_alloc.c
parentd8bae33dddc03dc652e1d8cfceebf4f753939de7 (diff)
downloadlinux-f86e4271978bd93db466d6a95dad4b0fdcdb04f6.tar.xz
mm: check the return value of lookup_page_ext for all call sites
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 <yang.shi@linaro.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.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.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f8f3bfc..d27e8b9 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -656,6 +656,9 @@ static inline void set_page_guard(struct zone *zone, struct page *page,
return;
page_ext = lookup_page_ext(page);
+ if (unlikely(!page_ext))
+ return;
+
__set_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
INIT_LIST_HEAD(&page->lru);
@@ -673,6 +676,9 @@ static inline void clear_page_guard(struct zone *zone, struct page *page,
return;
page_ext = lookup_page_ext(page);
+ if (unlikely(!page_ext))
+ return;
+
__clear_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);
set_page_private(page, 0);