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: <CAHk-=wgwJptCbaHwt+TpGgh04fTVAHd60AY3Jj1rX+Spf0fVyg@mail.gmail.com>
Date:   Sun, 11 Jun 2023 22:34:29 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Dave Chinner <david@...morbit.com>
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 10:16 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 "==".

Not that I'm at all convinced that that will fix the problem you are
seeing, but at least it shouldn't have made things worse like the
getting the condition completely wrong did.

                    Linus