From: Serhei Makarov <smakarov@redhat.com>
To: linux-audit@redhat.com, bpf@vger.kernel.org
Cc: Jerome Marchand <jmarchan@redhat.com>,
Daniel Borkmann <daniel@iogearbox.net>,
ast@kernel.org, Frank Eigler <fche@redhat.com>,
Jiri Olsa <jolsa@redhat.com>,
guro@fb.com
Subject: Re: deadlock bug related to bpf,audit subsystems
Date: Thu, 18 Mar 2021 12:43:03 -0400 [thread overview]
Message-ID: <CANYvDQOH5ZDpQBAHtz13YNiJ2Bhd56wnoas71UdYco62g-xBDg@mail.gmail.com> (raw)
In-Reply-To: <CANYvDQN7H5tVp47fbYcRasv4XF07eUbsDwT_eDCHXJUj43J7jQ@mail.gmail.com>
On Thu, Mar 18, 2021 at 10:43 AM Serhei Makarov <smakarov@redhat.com> wrote:
> Jiri Olsa also reports seeing a similar deadlock at v5.10. I'm in the
> middle of double-checking my bisection which ended up at a
> seemingly-unrelated commit [2]
>
> [1] https://bugzilla.redhat.com/show_bug.cgi?id=1938312
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.11-rc7&id=2dcb3964544177c51853a210b6ad400de78ef17d
I've confirmed that my first bisection was incorrect by testing
@1c2f67308af4 mm: thp: fix MADV_REMOVE deadlock on shmem THP
and reproducing the deadlock. Previously this commit was marked as
good, so it seems a kernel with the bug can sometimes pass the test.
I'll double check rc6 next since I have the kernel handy. If
5.11.0-rc6 can also be made to fail, with Jiri Olsa's report it'd be
necessary to do a wider search.
There may be commits with intent similar to
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8d92db5c04d103
which tightened some of the behaviour of kernel reads, but affecting
the audit subsystem?
The actual stack trace that leads to deadlock goes through
security_locked_down() which was present since the original patch
reworking probe_read into separate probe_read_{user,kernel} helpers
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v5.11-rc7&id=6ae08ae3dea2
-- Serhei
--
Linux-audit mailing list
Linux-audit@redhat.com
https://listman.redhat.com/mailman/listinfo/linux-audit
next prev parent reply other threads:[~2021-03-18 16:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <2ed7a55e-7def-7faf-fc47-991b867bff9e@iogearbox.net>
[not found] ` <CANYvDQOfygmqv0V-1PuzXV8ZFzk0uD566oEF3v9uX21G4fSFKg@mail.gmail.com>
[not found] ` <1e410caf-019a-ade7-465d-3d936d2f7dc6@iogearbox.net>
[not found] ` <5845cef9-5aaf-f85e-8280-472f61ddaeed@iogearbox.net>
[not found] ` <CANYvDQNCKmEy9ZzPRvhNYvK0=TKk1pRS=seUuAkby92ic8tVqw@mail.gmail.com>
[not found] ` <f97bd923-bf12-69a0-f0a8-c9a764abbed2@iogearbox.net>
[not found] ` <YFIwzhE00OpU1zro@krava>
[not found] ` <ff0db44e-aa55-da94-785f-ba10792a5ae1@iogearbox.net>
[not found] ` <YFKOeGqUwBPTkPzT@krava>
[not found] ` <61494cfb-1ceb-4886-3023-1ac0b35697d6@iogearbox.net>
[not found] ` <YFM+Ijeu4bN4IzH1@krava>
2021-03-18 14:43 ` deadlock bug related to bpf,audit subsystems Serhei Makarov
2021-03-18 16:43 ` Serhei Makarov [this message]
2021-03-18 17:44 ` Paul Moore
2021-03-18 17:45 ` Paul Moore
2021-03-18 18:19 ` Paul Moore
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