From: Yang Shi <yang.shi@xxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxx: fix build-breaking typos] [arnd@xxxxxxxx: fix build problems from lookup_page_ext] Link: http://lkml.kernel.org/r/6285269.2CksypHdYp@wuerfel [akpm@xxxxxxxxxxxxxxxxxxxx: coding-style fixes] Link: http://lkml.kernel.org/r/1464023768-31025-1-git-send-email-yang.shi@xxxxxxxxxx Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxx> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/page_idle.h | 43 ++++++++++++++++++++++++++++++------ mm/page_alloc.c | 6 +++++ mm/page_owner.c | 26 +++++++++++++++++++++ mm/page_poison.c | 8 +++++- mm/vmstat.c | 2 + 5 files changed, 77 insertions(+), 8 deletions(-) diff -puN include/linux/page_idle.h~mm-check-the-return-value-of-lookup_page_ext-for-all-call-sites include/linux/page_idle.h --- a/include/linux/page_idle.h~mm-check-the-return-value-of-lookup_page_ext-for-all-call-sites +++ a/include/linux/page_idle.h @@ -46,33 +46,62 @@ extern struct page_ext_operations page_i 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 */ diff -puN mm/page_alloc.c~mm-check-the-return-value-of-lookup_page_ext-for-all-call-sites mm/page_alloc.c --- a/mm/page_alloc.c~mm-check-the-return-value-of-lookup_page_ext-for-all-call-sites +++ a/mm/page_alloc.c @@ -656,6 +656,9 @@ static inline void set_page_guard(struct 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(stru 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); diff -puN mm/page_owner.c~mm-check-the-return-value-of-lookup_page_ext-for-all-call-sites mm/page_owner.c --- a/mm/page_owner.c~mm-check-the-return-value-of-lookup_page_ext-for-all-call-sites +++ a/mm/page_owner.c @@ -55,6 +55,8 @@ void __reset_page_owner(struct page *pag for (i = 0; i < (1 << order); i++) { page_ext = lookup_page_ext(page + i); + if (unlikely(!page_ext)) + continue; __clear_bit(PAGE_EXT_OWNER, &page_ext->flags); } } @@ -62,6 +64,7 @@ void __reset_page_owner(struct page *pag void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask) { struct page_ext *page_ext = lookup_page_ext(page); + struct stack_trace trace = { .nr_entries = 0, .max_entries = ARRAY_SIZE(page_ext->trace_entries), @@ -69,6 +72,9 @@ void __set_page_owner(struct page *page, .skip = 3, }; + if (unlikely(!page_ext)) + return; + save_stack_trace(&trace); page_ext->order = order; @@ -82,6 +88,8 @@ void __set_page_owner(struct page *page, void __set_page_owner_migrate_reason(struct page *page, int reason) { struct page_ext *page_ext = lookup_page_ext(page); + if (unlikely(!page_ext)) + return; page_ext->last_migrate_reason = reason; } @@ -89,6 +97,12 @@ void __set_page_owner_migrate_reason(str gfp_t __get_page_owner_gfp(struct page *page) { struct page_ext *page_ext = lookup_page_ext(page); + if (unlikely(!page_ext)) + /* + * The caller just returns 0 if no valid gfp + * So return 0 here too. + */ + return 0; return page_ext->gfp_mask; } @@ -99,6 +113,9 @@ void __copy_page_owner(struct page *oldp struct page_ext *new_ext = lookup_page_ext(newpage); int i; + if (unlikely(!old_ext || !new_ext)) + return; + new_ext->order = old_ext->order; new_ext->gfp_mask = old_ext->gfp_mask; new_ext->nr_entries = old_ext->nr_entries; @@ -193,6 +210,11 @@ void __dump_page_owner(struct page *page gfp_t gfp_mask = page_ext->gfp_mask; int mt = gfpflags_to_migratetype(gfp_mask); + if (unlikely(!page_ext)) { + pr_alert("There is not page extension available.\n"); + return; + } + if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) { pr_alert("page_owner info is not active (free page?)\n"); return; @@ -251,6 +273,8 @@ read_page_owner(struct file *file, char } page_ext = lookup_page_ext(page); + if (unlikely(!page_ext)) + continue; /* * Some pages could be missed by concurrent allocation or free, @@ -317,6 +341,8 @@ static void init_pages_in_zone(pg_data_t continue; page_ext = lookup_page_ext(page); + if (unlikely(!page_ext)) + continue; /* Maybe overraping zone */ if (test_bit(PAGE_EXT_OWNER, &page_ext->flags)) diff -puN mm/page_poison.c~mm-check-the-return-value-of-lookup_page_ext-for-all-call-sites mm/page_poison.c --- a/mm/page_poison.c~mm-check-the-return-value-of-lookup_page_ext-for-all-call-sites +++ a/mm/page_poison.c @@ -54,6 +54,9 @@ static inline void set_page_poison(struc struct page_ext *page_ext; page_ext = lookup_page_ext(page); + if (unlikely(!page_ext)) + return; + __set_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags); } @@ -62,6 +65,9 @@ static inline void clear_page_poison(str struct page_ext *page_ext; page_ext = lookup_page_ext(page); + if (unlikely(!page_ext)) + return; + __clear_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags); } @@ -70,7 +76,7 @@ bool page_is_poisoned(struct page *page) struct page_ext *page_ext; page_ext = lookup_page_ext(page); - if (!page_ext) + if (unlikely(!page_ext)) return false; return test_bit(PAGE_EXT_DEBUG_POISON, &page_ext->flags); diff -puN mm/vmstat.c~mm-check-the-return-value-of-lookup_page_ext-for-all-call-sites mm/vmstat.c --- a/mm/vmstat.c~mm-check-the-return-value-of-lookup_page_ext-for-all-call-sites +++ a/mm/vmstat.c @@ -1061,6 +1061,8 @@ static void pagetypeinfo_showmixedcount_ continue; page_ext = lookup_page_ext(page); + if (unlikely(!page_ext)) + continue; if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags)) continue; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
