On Mar 07, 2023 / 18:28, Yu Kuai wrote:
> Hi, Jan
>
> 在 2023/03/07 18:20, Jan Kara 写道:
[...]
> > So rather doing something like:
> >
> > bfqq_data->stable_merge_bfqq = NULL;
> > new_bfqq = bfq_setup_stable_merge(bfqd, bfqq,
> > stable_merge_bfqq, bfqq_data);
> > bfq_put_stable_ref(stable_merge_bfqq);
> > return new_bfqq;
> >
> > should work in bfq_setup_cooperator().
>
> Yes, this will work.
Based on the description above, I quickly created the dirty patch below, and
confirmed it avoids the BUG. Looks good. Jan, Yu, thanks for the quick actions.
Let me wait for the formal patch.
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 8a8d4441519c..50eb435efed0 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -2932,15 +2932,15 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
msecs_to_jiffies(bfq_late_stable_merging))) {
struct bfq_queue *stable_merge_bfqq =
bfqq_data->stable_merge_bfqq;
+ static struct bfq_queue *new_bfqq;
/* deschedule stable merge, because done or aborted here */
- bfq_put_stable_ref(stable_merge_bfqq);
-
bfqq_data->stable_merge_bfqq = NULL;
-
- return bfq_setup_stable_merge(bfqd, bfqq,
- stable_merge_bfqq,
- bfqq_data);
+ new_bfqq = bfq_setup_stable_merge(bfqd, bfqq,
+ stable_merge_bfqq,
+ bfqq_data);
+ bfq_put_stable_ref(stable_merge_bfqq);
+ return new_bfqq;
}
}
--
Shin'ichiro Kawasaki
