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-rw-r--r--block/blk-iocost.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 089fcb9cfc..7ee8d85c2c 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -1353,6 +1353,13 @@ static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now)
lockdep_assert_held(&iocg->waitq.lock);
+ /*
+ * If the delay is set by another CPU, we may be in the past. No need to
+ * change anything if so. This avoids decay calculation underflow.
+ */
+ if (time_before64(now->now, iocg->delay_at))
+ return false;
+
/* calculate the current delay in effect - 1/2 every second */
tdelta = now->now - iocg->delay_at;
if (iocg->delay)