linux-kernel - Re: [6.5-rc5 regression] core dump hangs (was Re: [Bug report] fstests generic/051 (on xfs) hang on latest linux v6.5-rc5+)

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Message-ID: <ZIax1FLfNajWk25A@dread.disaster.area>
Date:   Mon, 12 Jun 2023 15:49:08 +1000
From:   Dave Chinner <david@...morbit.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     "Darrick J. Wong" <djwong@...nel.org>,
        Zorro Lang <zlang@...hat.com>, linux-xfs@...r.kernel.org,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Mike Christie <michael.christie@...cle.com>,
        "Michael S. Tsirkin" <mst@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [6.5-rc5 regression] core dump hangs (was Re: [Bug report]
 fstests generic/051 (on xfs) hang on latest linux v6.5-rc5+)

On Sun, Jun 11, 2023 at 10:34:29PM -0700, Linus Torvalds wrote:
> On Sun, Jun 11, 2023 at 10:16 PM Dave Chinner <david@...morbit.com> wrote:
> >
> > > +             /* vhost workers don't participate in core dups */
> > > +             if ((current->flags & (PF_IO_WORKER | PF_USER_WORKER)) != PF_USER_WORKER)
> > > +                     goto out;
> > > +
> >
> > That would appear to make things worse. mkfs.xfs hung in Z state on
> > exit and never returned to the shell.
> 
> Well, duh, that's because I'm a complete nincompoop who just copied
> the condition from the other cases, but those other cases were for
> testing the "this is *not* a vhost worker".
> 
> Here the logic - as per the comment I added - was supposed to be "is
> this a vhost worker".
> 
> So that "!=" should obviously have been a "==".

Same as without the condition - all the fsstress tasks hang in
do_coredump().

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com