From: Peter Zijlstra <peterz@infradead.org>
To: syzbot <syzbot+3daecb3e8271380aeb51@syzkaller.appspotmail.com>
Cc: acme@kernel.org, alexander.shishkin@linux.intel.com,
andriin@fb.com, ast@kernel.org, bpf@vger.kernel.org,
daniel@iogearbox.net, jolsa@redhat.com, kafai@fb.com,
linux-kernel@vger.kernel.org, mark.rutland@arm.com,
mingo@redhat.com, namhyung@kernel.org, netdev@vger.kernel.org,
songliubraving@fb.com, syzkaller-bugs@googlegroups.com,
yhs@fb.com
Subject: Re: WARNING: locking bug in __perf_event_task_sched_in
Date: Wed, 4 Mar 2020 14:53:51 +0100 [thread overview]
Message-ID: <20200304135351.GN2596@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <0000000000005c967305a006d54d@google.com>
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.
next prev parent reply other threads:[~2020-03-04 13:54 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 [this message]
2020-03-04 14:01 ` Dmitry Vyukov
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