Re: BUG: MAX_LOCKDEP_CHAINS too low!

From: syzbot
Date: Sun Oct 20 2019 - 19:33:23 EST


syzbot has found a reproducer for the following crash on:

HEAD commit: 4fe34d61 Merge branch 'x86-urgent-for-linus' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1176cd40e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=e0ac4d9b35046343
dashboard link: https://syzkaller.appspot.com/bug?extid=aaa6fa4949cc5d9b7b25
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14150b40e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12e122ff600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+aaa6fa4949cc5d9b7b25@xxxxxxxxxxxxxxxxxxxxxxxxx

BUG: MAX_LOCKDEP_CHAINS too low!
turning off the locking correctness validator.
CPU: 0 PID: 11772 Comm: kworker/u5:486 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci1600 hci_power_on
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
add_chain_cache kernel/locking/lockdep.c:2816 [inline]
lookup_chain_cache_add kernel/locking/lockdep.c:2915 [inline]
validate_chain kernel/locking/lockdep.c:2936 [inline]
__lock_acquire.cold+0x325/0x385 kernel/locking/lockdep.c:3955
lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
process_one_work+0x91c/0x1740 kernel/workqueue.c:2245
worker_thread+0x98/0xe40 kernel/workqueue.c:2415
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352