From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Dmitry Dolgov <9erthalion6@gmail.com>
Cc: bpf@vger.kernel.org, linux-rt-users@vger.kernel.org,
ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org
Subject: Re: bpf_ringbuf_reserve deadlock on rt kernels
Date: Thu, 13 Jun 2024 12:40:58 +0200 [thread overview]
Message-ID: <20240613104058.bwDKdWSV@linutronix.de> (raw)
In-Reply-To: <mt2yblzo4ezlx4vjfmw3pul3cqgd27oddbaq2coqjkcp342cni@ob4gkaxfz7mg>
On 2024-06-13 12:23:46 [+0200], Dmitry Dolgov wrote:
> > On Wed, Jun 12, 2024 at 04:32:23PM GMT, Sebastian Andrzej Siewior wrote:
> >
> > > The BPF program in question is attached to sched_switch. The issue seems
> > > to be similar to a couple of syzkaller reports [1], [2], although the
> > > latter one is about nested progs, which seems to be not the case here.
> > > Talking about nested progs, applying a similar approach as in [3]
> > > reworked for bpf_ringbuf, elliminates the issue.
> > >
> > > Do I miss anything, is it a known issue? Any ideas how to address that?
> >
> > I haven't attached bpf program to trace-events so this new to me. But if
> > you BPF attach programs to trace-events then there might be more things
> > that can go wrong…
>
> Things related to RT kernels, or something else?
Related to RT kernel. The trace-event is invoked with disabled
preemption. This means locking is limit to raw_spinlock_t and no memory
allocation are allowed. Otherwise the splat below will appear.
Sebastian
prev parent reply other threads:[~2024-06-13 10:41 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-10 15:17 bpf_ringbuf_reserve deadlock on rt kernels Dmitry Dolgov
2024-06-12 14:32 ` Sebastian Andrzej Siewior
2024-06-13 10:23 ` Dmitry Dolgov
2024-06-13 10:40 ` Sebastian Andrzej Siewior [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240613104058.bwDKdWSV@linutronix.de \
--to=bigeasy@linutronix.de \
--cc=9erthalion6@gmail.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=linux-rt-users@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox