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-rw-r--r--block/cfq-iosched.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index ee8a90c7c46..e8525fa7282 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1314,7 +1314,15 @@ static void cfq_exit_single_io_context(struct io_context *ioc,
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
- __cfq_exit_single_io_context(cfqd, cic);
+
+ /*
+ * Ensure we get a fresh copy of the ->key to prevent
+ * race between exiting task and queue
+ */
+ smp_read_barrier_depends();
+ if (cic->key)
+ __cfq_exit_single_io_context(cfqd, cic);
+
spin_unlock_irqrestore(q->queue_lock, flags);
}
}