From f86e4271978bd93db466d6a95dad4b0fdcdb04f6 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 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 --- include/linux/page_idle.h | 43 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 36 insertions(+), 7 deletions(-) (limited to 'include') diff --git a/include/linux/page_idle.h b/include/linux/page_idle.h index bf268fa92c5b..fec40271339f 100644 --- a/include/linux/page_idle.h +++ b/include/linux/page_idle.h @@ -46,33 +46,62 @@ extern struct page_ext_operations page_idle_ops; static inline bool page_is_young(struct page *page) { - return test_bit(PAGE_EXT_YOUNG, &lookup_page_ext(page)->flags); + struct page_ext *page_ext = lookup_page_ext(page); + + if (unlikely(!page_ext)) + return false; + + return test_bit(PAGE_EXT_YOUNG, &page_ext->flags); } static inline void set_page_young(struct page *page) { - set_bit(PAGE_EXT_YOUNG, &lookup_page_ext(page)->flags); + struct page_ext *page_ext = lookup_page_ext(page); + + if (unlikely(!page_ext)) + return; + + set_bit(PAGE_EXT_YOUNG, &page_ext->flags); } static inline bool test_and_clear_page_young(struct page *page) { - return test_and_clear_bit(PAGE_EXT_YOUNG, - &lookup_page_ext(page)->flags); + struct page_ext *page_ext = lookup_page_ext(page); + + if (unlikely(!page_ext)) + return false; + + return test_and_clear_bit(PAGE_EXT_YOUNG, &page_ext->flags); } static inline bool page_is_idle(struct page *page) { - return test_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags); + struct page_ext *page_ext = lookup_page_ext(page); + + if (unlikely(!page_ext)) + return false; + + return test_bit(PAGE_EXT_IDLE, &page_ext->flags); } static inline void set_page_idle(struct page *page) { - set_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags); + struct page_ext *page_ext = lookup_page_ext(page); + + if (unlikely(!page_ext)) + return; + + set_bit(PAGE_EXT_IDLE, &page_ext->flags); } static inline void clear_page_idle(struct page *page) { - clear_bit(PAGE_EXT_IDLE, &lookup_page_ext(page)->flags); + struct page_ext *page_ext = lookup_page_ext(page); + + if (unlikely(!page_ext)) + return; + + clear_bit(PAGE_EXT_IDLE, &page_ext->flags); } #endif /* CONFIG_64BIT */ -- cgit v1.2.3-59-g8ed1b