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-rw-r--r--include/linux/sched/mm.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 26307cdc3969..b84e0fde1d72 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -39,6 +39,11 @@ static inline void mmgrab(struct mm_struct *mm)
extern void __mmdrop(struct mm_struct *);
static inline void mmdrop(struct mm_struct *mm)
{
+ /*
+ * The implicit full barrier implied by atomic_dec_and_test() is
+ * required by the membarrier system call before returning to
+ * user-space, after storing to rq->curr.
+ */
if (unlikely(atomic_dec_and_test(&mm->mm_count)))
__mmdrop(mm);
}