blob: 4c2088ba84e936fb86b7d89ac60ac97153fbbe34 [file] [log] [blame]
From 80e342252aaaa7c436b7103d74e12022369b5a6b Mon Sep 17 00:00:00 2001
From: Paolo Valente <>
Date: Mon, 3 Feb 2020 11:40:56 +0100
Subject: [PATCH] block, bfq: get extra ref to prevent a queue from being freed
during a group move
commit ecedd3d7e19911ab8fe42f17b77c0a30fe7f4db3 upstream.
In bfq_bfqq_move(), the bfq_queue, say Q, to be moved to a new group
may happen to be deactivated in the scheduling data structures of the
source group (and then activated in the destination group). If Q is
referred only by the data structures in the source group when the
deactivation happens, then Q is freed upon the deactivation.
This commit addresses this issue by getting an extra reference before
the possible deactivation, and releasing this extra reference after Q
has been moved.
Tested-by: Chris Evich <>
Tested-by: Oleksandr Natalenko <>
Signed-off-by: Paolo Valente <>
Signed-off-by: Jens Axboe <>
Signed-off-by: Paul Gortmaker <>
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index b3796a40a61a..ce7377917b8c 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -557,6 +557,12 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
+ /*
+ * get extra reference to prevent bfqq from being freed in
+ * next possible deactivate
+ */
+ bfqq->ref++;
if (bfq_bfqq_busy(bfqq))
bfq_deactivate_bfqq(bfqd, bfqq, false, false);
else if (entity->on_st)
@@ -576,6 +582,8 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
+ /* release extra ref taken above */
+ bfq_put_queue(bfqq);