linux-kernel - Re: [PATCH 1/8] signal: Make SIGKILL during coredumps an explicit special case

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Date:   Sat, 8 Jan 2022 20:13:06 +0100
From:   Heiko Carstens <hca@...ux.ibm.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        Alexey Gladkov <legion@...nel.org>,
        Kyle Huey <me@...ehuey.com>, Oleg Nesterov <oleg@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH 1/8] signal: Make SIGKILL during coredumps an explicit
 special case

On Tue, Jan 04, 2022 at 01:47:05PM -0600, Eric W. Biederman wrote:
> Currently I suspect changing wait_event_uninterruptible to
> wait_event_killable, is causing problems.
> 
> Or perhaps there is some reason tasks that have already entered do_exit
> need to have fatal_signal_pending set. (The will have
> fatal_signal_pending set up until they enter get_signal which calls
> do_group_exit which calls do_exit).
> 
> Which is why I am trying to reproduce the reported failure so I can get
> the kernel to tell me what is going on.  If this is not resolved quickly
> I won't send you this change, and I will pull it out of linux-next.

It would have been good if you would have removed this from linux-next
already.

Anyway, now I also had to spend quite some time to bisect why several test
suites just hang with linux-next. It's probably because of holidays that
you didn't get more bug reports.

On s390

- ltp
- elfutils selftests
- seccomp kernel selftests

hang with linux-next.

I bisected the problem to this patch using elfutils selftests:

git clone git://sourceware.org/git/elfutils.git
cd elfutils
autoreconf -fi
./configure --enable-maintainer-mode --disable-debuginfod
make -j $(nproc) > /dev/null
cd tests
make -j $(nproc) check

Note: I actually didn't verify if this also causes ltp+seccomp selftests
      to hang. I just assume it is the case.