happOn Wed, Mar 4, 2020 at 2:54 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > ------------[ 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