Hi!
在 2022/10/11 20:54, Yu Kuai 写道:
Hi!
在 2022/10/11 18:21, Jinlong Chen 写道:
We got a reference of the io scheduler module in
blk_mq_elv_switch_none to prevent the module from
being removed. We need to put that reference back
once we are done.
However, if blk_mq_elv_switch_none() failed due to OOM, and module
reference is not acquired, blk_mq_elv_switch_back() will still be
called. This seems not to be the right fix.
Please ignore this.
I got it now if switch none failed, old queue is not added to the list,
and later blk_lookup_qe_pair() will fail to lookup the queue.
Thanks,
Kuai
Thanks,
Kuai
Signed-off-by: Jinlong Chen <chenjinlong2016@xxxxxxxxxxx>
---
block/blk-mq.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 8070b6c10e8d..8dfe3bf3e599 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -4595,6 +4595,13 @@ static void blk_mq_elv_switch_back(struct
list_head *head,
mutex_lock(&q->sysfs_lock);
elevator_switch(q, t);
+ /**
+ * We got a reference of the io scheduler module in
+ * blk_mq_elv_switch_none to prevent the module from
+ * being removed. We need to put that reference back
+ * once we are done.
+ */
+ module_put(t->elevator_owner);
mutex_unlock(&q->sysfs_lock);
}
.
