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>

diff --git a/include/linux/page_idle.h b/include/linux/page_idle.h
index bf268fa92c5b34a1bffce97a8cd38acf2b161059..fec40271339f8044aa1e3f1743e62017f146f9cc 100644 (file)
--- 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 */
 

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f8f3bfc435eec5bf0144798f6b890e6deacee0f6..d27e8b968ac35b1d85cb02621f958553e3c12f0b 100644 (file)
--- 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);

diff --git a/mm/page_owner.c b/mm/page_owner.c
index 792b56da13d8564f4f6fbab68dcf46297bd13c30..c6cda3e36212833f78189c3a93b7dc80f8bc7ec9 100644 (file)
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -55,6 +55,8 @@ void __reset_page_owner(struct page *page, unsigned int order)
 
        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 *page, unsigned int order)
 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, unsigned int order, gfp_t gfp_mask)
                .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, unsigned int order, gfp_t gfp_mask)
 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(struct page *page, int reason)
 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 *oldpage, struct page *newpage)
        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 __user *buf, size_t count, loff_t *ppos)
                }
 
                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 *pgdat, struct zone *zone)
                                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 --git a/mm/page_poison.c b/mm/page_poison.c
index 1eae5fad2446b4b7b069fde3d0e5b373418ea7bb..2e647c65916b91b00177837370e210d71c568f5e 100644 (file)
--- a/mm/page_poison.c
+++ b/mm/page_poison.c
@@ -54,6 +54,9 @@ static inline void set_page_poison(struct page *page)
        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(struct page *page)
        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 --git a/mm/vmstat.c b/mm/vmstat.c
index 77e42ef388c2a832169d4bcace8a505c45d95516..cb2a67bb41581de147427e2289190beea33f69da 100644 (file)
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1061,6 +1061,8 @@ static void pagetypeinfo_showmixedcount_print(struct seq_file *m,
                                continue;
 
                        page_ext = lookup_page_ext(page);
+                       if (unlikely(!page_ext))
+                               continue;
 
                        if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
                                continue;