Re: [fsdax xfs] Regression panic at inode_switch_wbs_work_fn

[Murphy Zhou <jencce.kernel@gmail.com>]

Hi,

On Fri, Jul 16, 2021 at 12:07 AM Roman Gushchin <guro@fb.com> wrote:
>
> On Thu, Jul 15, 2021 at 06:10:22PM +0800, Murphy Zhou wrote:
> > Hi,
> >
> > #Looping generic/270 of xfstests[1] on pmem ramdisk with
> > mount option:  -o dax=always
> > mkfs.xfs option: -f -b size=4096 -m reflink=0
> > can hit this panic now.
> >
> > #It's not reproducible on ext4.
> > #It's not reproducible without dax=always.
>
> Hi Murphy!
>
> Thank you for the report!
>
> Can you, please, check if the following patch fixes the problem?

No. Still the same panic.

>
> Thank you!
>
> --
>
> diff --git a/mm/backing-dev.c b/mm/backing-dev.c
> index 271f2ca862c8..f5561ea7d90a 100644
> --- a/mm/backing-dev.c
> +++ b/mm/backing-dev.c
> @@ -398,12 +398,12 @@ static void cgwb_release_workfn(struct work_struct *work)
>         blkcg_unpin_online(blkcg);
>
>         fprop_local_destroy_percpu(&wb->memcg_completions);
> -       percpu_ref_exit(&wb->refcnt);
>
>         spin_lock_irq(&cgwb_lock);
>         list_del(&wb->offline_node);
>         spin_unlock_irq(&cgwb_lock);
>
> +       percpu_ref_exit(&wb->refcnt);
>         wb_exit(wb);
>         WARN_ON_ONCE(!list_empty(&wb->b_attached));
>         kfree_rcu(wb, rcu);