From: Yu Kuai <yukuai3@huawei.com> stable inclusion from stable-5.10.58 commit 821e6a61335443cd3d56c85427c7f950cb4fd551 bugzilla: 176984 https://gitee.com/openeuler/kernel/issues/I4E2P4 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 8d75d0eff6887bcac7225e12b9c75595e523d92d ] If queue is dying while iolatency_set_limit() is in progress, blk_get_queue() won't increment the refcount of the queue. However, blk_put_queue() will still decrement the refcount later, which will cause the refcout to be unbalanced. Thus error out in such case to fix the problem. Fixes: 8c772a9bfc7c ("blk-iolatency: fix IO hang due to negative inflight counter") Signed-off-by: Yu Kuai <yukuai3@huawei.com> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20210805124645.543797-1-yukuai3@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Chen Jun <chenjun102@huawei.com> Acked-by: Weilong Chen <chenweilong@huawei.com> Signed-off-by: Chen Jun <chenjun102@huawei.com> --- block/blk-iolatency.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index 81be0096411d..d8b0d8bd132b 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -833,7 +833,11 @@ static ssize_t iolatency_set_limit(struct kernfs_open_file *of, char *buf, enable = iolatency_set_min_lat_nsec(blkg, lat_val); if (enable) { - WARN_ON_ONCE(!blk_get_queue(blkg->q)); + if (!blk_get_queue(blkg->q)) { + ret = -ENODEV; + goto out; + } + blkg_get(blkg); } -- 2.20.1