mm: page_alloc: clear PG_locked before checking flags on free

da456f1 "page allocator: do not disable interrupts in free_page_mlock()" moved
the PG_mlocked clearing after the flag sanity checking which makes mlocked
pages always trigger 'bad page'.  Fix this by clearing the bit up front.

Reported--and-debugged-by: Peter Chubb <peter.chubb@nicta.com.au>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Tested-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 5 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6f0753fe694c..30d5093a099d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -488,7 +488,6 @@ static inline void __free_one_page(struct page *page,
  */
 static inline void free_page_mlock(struct page *page)
 {
-        __ClearPageMlocked(page);
         __dec_zone_page_state(page, NR_MLOCK);
         __count_vm_event(UNEVICTABLE_MLOCKFREED);
 }
@@ -558,7 +557,7 @@ static void __free_pages_ok(struct page *page, unsigned int order)
         unsigned long flags;
         int i;
         int bad = 0;
-        int clearMlocked = PageMlocked(page);
+        int wasMlocked = TestClearPageMlocked(page);
 
         kmemcheck_free_shadow(page, order);
 
@@ -576,7 +575,7 @@ static void __free_pages_ok(struct page *page, unsigned int order)
         kernel_map_pages(page, 1 << order, 0);
 
         local_irq_save(flags);
-        if (unlikely(clearMlocked))
+        if (unlikely(wasMlocked))
                 free_page_mlock(page);
         __count_vm_events(PGFREE, 1 << order);
         free_one_page(page_zone(page), page, order,
@@ -1022,7 +1021,7 @@ static void free_hot_cold_page(struct page *page, int cold)
         struct zone *zone = page_zone(page);
         struct per_cpu_pages *pcp;
         unsigned long flags;
-        int clearMlocked = PageMlocked(page);
+        int wasMlocked = TestClearPageMlocked(page);
 
         kmemcheck_free_shadow(page, 0);
 
@@ -1041,7 +1040,7 @@ static void free_hot_cold_page(struct page *page, int cold)
         pcp = &zone_pcp(zone, get_cpu())->pcp;
         set_page_private(page, get_pageblock_migratetype(page));
         local_irq_save(flags);
-        if (unlikely(clearMlocked))
+        if (unlikely(wasMlocked))
                 free_page_mlock(page);
         __count_vm_event(PGFREE);