From 7b8b061afc691a963480c9040670b8699c86e467 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Tue, 17 Dec 2013 10:44:45 +1100 Subject: [PATCH] mm: numa: guarantee that tlb_flush_pending updates are visible before page table updates According to documentation on barriers, stores issued before a LOCK can complete after the lock implying that it's possible tlb_flush_pending can be visible after a page table update. As per revised documentation, this patch adds a smp_mb__before_spinlock to guarantee the correct ordering. Signed-off-by: Mel Gorman Acked-by: Paul E. McKenney Reviewed-by: Rik van Riel Cc: Signed-off-by: Andrew Morton --- include/linux/mm_types.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index e5c49c30460f..ad0616f2fe2c 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -482,7 +482,12 @@ static inline bool mm_tlb_flush_pending(struct mm_struct *mm) static inline void set_tlb_flush_pending(struct mm_struct *mm) { mm->tlb_flush_pending = true; - barrier(); + + /* + * Guarantee that the tlb_flush_pending store does not leak into the + * critical section updating the page tables + */ + smp_mb__before_spinlock(); } /* Clearing is done after a TLB flush, which also provides a barrier. */ static inline void clear_tlb_flush_pending(struct mm_struct *mm) -- 2.39.5