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-rw-r--r--block/blk-flush.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 968162579234..0d5a9c1da1fc 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -297,8 +297,14 @@ static bool blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq)
if (fq->flush_pending_idx != fq->flush_running_idx || list_empty(pending))
return false;
- /* C2 and C3 */
+ /* C2 and C3
+ *
+ * For blk-mq + scheduling, we can risk having all driver tags
+ * assigned to empty flushes, and we deadlock if we are expecting
+ * other requests to make progress. Don't defer for that case.
+ */
if (!list_empty(&fq->flush_data_in_flight) &&
+ !(q->mq_ops && q->elevator) &&
time_before(jiffies,
fq->flush_pending_since + FLUSH_PENDING_TIMEOUT))
return false;