commit af2c1401e6f9177483be4fad876d0073669df9df upstream.
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 <mgorman@xxxxxxx>
Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
---
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 0edf600..8e082f1 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -478,7 +478,12 @@ 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)
--
1.8.4
--
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