From: Dmitry Vyukov <dvyukov@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: syzbot <syzbot+3daecb3e8271380aeb51@syzkaller.appspotmail.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Andrii Nakryiko <andriin@fb.com>,
Alexei Starovoitov <ast@kernel.org>, bpf <bpf@vger.kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
jolsa@redhat.com, Martin KaFai Lau <kafai@fb.com>,
LKML <linux-kernel@vger.kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Ingo Molnar <mingo@redhat.com>,
Namhyung Kim <namhyung@kernel.org>,
netdev <netdev@vger.kernel.org>, Song Liu <songliubraving@fb.com>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
Yonghong Song <yhs@fb.com>
Subject: Re: WARNING: locking bug in __perf_event_task_sched_in
Date: Wed, 4 Mar 2020 15:01:05 +0100 [thread overview]
Message-ID: <CACT4Y+b2Xu_Oj5GnnQFeYQBnyx5+3Fdeaj-OJY4jLyxoS0szkw@mail.gmail.com> (raw)
In-Reply-To: <20200304135351.GN2596@hirez.programming.kicks-ass.net>
happOn Wed, Mar 4, 2020 at 2:54 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Wed, Mar 04, 2020 at 04:48:13AM -0800, syzbot wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit: f8788d86 Linux 5.6-rc3
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=13bcd8f9e00000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=5d2e033af114153f
> > dashboard link: https://syzkaller.appspot.com/bug?extid=3daecb3e8271380aeb51
> > compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> >
> > Unfortunately, I don't have any reproducer for this crash yet.
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+3daecb3e8271380aeb51@syzkaller.appspotmail.com
> >
> > ------------[ cut here ]------------
> > DEBUG_LOCKS_WARN_ON(1)
> > WARNING: CPU: 0 PID: 22488 at kernel/locking/lockdep.c:167 hlock_class kernel/locking/lockdep.c:167 [inline]
> > WARNING: CPU: 0 PID: 22488 at kernel/locking/lockdep.c:167 __lock_acquire+0x18b8/0x1bc0 kernel/locking/lockdep.c:3950
>
> Something went sideways bad, could be you've overflowed lockdep_depth.
> For some reason the check:
>
> if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH))
>
> is rather late.. Dunno, most times I've hit lockdep errors like this,
> something else was screwy and we're just the ones to trip over it.
"BUG: MAX_LOCK_DEPTH too low!" is not happening on its own, the last
"BUG: MAX_LOCK_DEPTH too low!" happened 600 days ago:
https://syzkaller.appspot.com/bug?extid=802a5abb8abae86eb6de
prev parent reply other threads:[~2020-03-04 14:01 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-04 12:48 WARNING: locking bug in __perf_event_task_sched_in syzbot
2020-03-04 13:53 ` Peter Zijlstra
2020-03-04 14:01 ` Dmitry Vyukov [this message]
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