Re: [BUG] fs: dlm: possible ABBA deadlock

[Jia-Ju Bai]

On 2021/8/19 23:55, David Teigland wrote:
> On Thu, Aug 19, 2021 at 04:54:57PM +0800, Jia-Ju Bai wrote:
> > Hello,
> >
> > My static analysis tool reports a possible ABBA deadlock in the dlm
> > filesystem in Linux 5.10:
> >
> > dlm_recover_waiters_pre()
> >    mutex_lock(&ls->ls_waiters_mutex); --> line 5130
> >    recover_convert_waiter()
> >      _receive_convert_reply()
> >        lock_rsb()
> >          mutex_lock(&r->res_mutex); --> line 69
> >
> > dlm_recover_waiters_post()
> >    lock_rsb()
> >      mutex_lock(&r->res_mutex); --> line 69
> >    mutex_lock(&ls->ls_waiters_mutex); --> line 5307
> >
> > When dlm_recover_waiters_pre() and dlm_recover_waiters_post() are
> > concurrently executed, the deadlock can occur.
> >
> > I am not quite sure whether this possible deadlock is real and how to fix it
> > if it is real.
> > Any feedback would be appreciated, thanks :)
> They won't be concurrent, "pre" runs before recovery, and "post" is after.

Okay, thanks for your reply :)


Best wishes,
Jia-Ju Bai