[dm-devel] [PATCH 4/8] block: support delayed holder registration

[Guenter Roeck]

On Mon, Aug 16, 2021 at 09:21:58AM +0200, Christoph Hellwig wrote:
> On Sun, Aug 15, 2021 at 07:27:37AM -0700, Guenter Roeck wrote:
> > [   14.467748][    T1]  Possible unsafe locking scenario:
> > [   14.467748][    T1]
> > [   14.467928][    T1]        CPU0                    CPU1
> > [   14.468058][    T1]        ----                    ----
> > [   14.468187][    T1]   lock(&disk->open_mutex);
> > [   14.468317][    T1]                                lock(mtd_table_mutex);
> > [   14.468493][    T1]                                lock(&disk->open_mutex);
> > [   14.468671][    T1]   lock(mtd_table_mutex);
> 
> Oh, that ooks like a really old one, fixed by
> b7abb0516822 ("mtd: fix lock hierarchy in deregister_mtd_blktrans")
> in linux-next.

I have seen the problem in next-20210813 and that patch is there,
so that is somewhat unlikely.

Guenter