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 <[email protected]>
---
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);
}
--
2.31.1
On 8/5/21 6:46 AM, Yu Kuai wrote:
> 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.
Applied, thanks.
--
Jens Axboe
On Thu, Aug 05, 2021 at 08:46:45PM +0800, Yu Kuai wrote:
> 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 <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Thanks.
--
tejun