git: 811e27fa3c44 - main - jail: Add PD_KILL to remove a prison in prison_deref().

[Kyle Evans]

On Wed, Feb 24, 2021 at 11:53 PM James Gritton <jamie at freebsd.org> wrote:
>
> On 2021-02-24 21:29, Kyle Evans wrote:
> > On Tue, Feb 23, 2021 at 7:16 AM Alexander Richardson
> > <arichardson at freebsd.org> wrote:
> >>
> >> On Mon, 22 Feb 2021 at 20:28, Jamie Gritton <jamie at freebsd.org> wrote:
> >> >
> >> > The branch main has been updated by jamie:
> >> >
> >> > URL: https://cgit.FreeBSD.org/src/commit/?id=811e27fa3c445664e36071a7d08228fc7fb85676
> >> >
> >> > commit 811e27fa3c445664e36071a7d08228fc7fb85676
> >> > Author:     Jamie Gritton <jamie at FreeBSD.org>
> >> > AuthorDate: 2021-02-22 20:27:44 +0000
> >> > Commit:     Jamie Gritton <jamie at FreeBSD.org>
> >> > CommitDate: 2021-02-22 20:27:44 +0000
> >> >
> >> >     jail: Add PD_KILL to remove a prison in prison_deref().
> >> >
> >> >     Add the PD_KILL flag that instructs prison_deref() to take steps
> >> >     to actively kill a prison and its descendents, namely marking it
> >> >     PRISON_STATE_DYING, clearing its PR_PERSIST flag, and killing any
> >> >     attached processes.
> >> >
> >> >     This replaces a similar loop in sys_jail_remove(), bringing the
> >> >     operation under the same single hold on allprison_lock that it already
> >> >     has. It is also used to clean up failed jail (re-)creations in
> >> >     kern_jail_set(), which didn't generally take all the proper steps.
> >> >
> >> >     Differential Revision:  https://reviews.freebsd.org/D28473
> >>
> >> Hi Jamie,
> >>
> >> After this commit running cd /usr/tests/lib/libc/sys && kyua test
> >> cpuset_test renders the entire system unusable: all exec calls
> >> afterwards seem to fail. In Jenkins it's triggering a kernel panic:
> >> https://ci.freebsd.org/job/FreeBSD-main-amd64-test/17630/consoleFull
> >> Reverting this commit fixes the issue.
> >>
> >
> > Based on the backtrace and a wild stab in the dark, the last
> > prison_deref() in do_jail_attach() prior to successful return should
> > explicitly clear the PD_KILL flag from drflags.
> >
> > Thanks,
> >
> > Kyle Evans
>
> Yep, that's what's doing it.  Actually, PD_KILL has no business being
> passed to do_jail_attach in the first place.  Running a test on that
> right now.
>

Ah, good point! IMHO we should KASSERT() that as well in
do_jail_attach(); it doesn't feel like we can do anything sensible
with the flag there, so we might as well raise awareness that the
caller needs to be more careful if attach failure is significant to
the lifetime of the target.