syzbot

BUG: MAX_STACK_TRACE_ENTRIES too low!
turning off the locking correctness validator.
CPU: 1 PID: 4732 Comm: syz-executor.4 Not tainted 5.12.0-rc7-next-20210415-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 save_trace.cold+0x14/0x19 kernel/locking/lockdep.c:549
 check_prev_add kernel/locking/lockdep.c:2999 [inline]
 check_prevs_add kernel/locking/lockdep.c:3061 [inline]
 validate_chain kernel/locking/lockdep.c:3676 [inline]
 __lock_acquire+0x398f/0x5230 kernel/locking/lockdep.c:4902
 lock_acquire kernel/locking/lockdep.c:5512 [inline]
 lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5477
 __mutex_lock_common kernel/locking/mutex.c:949 [inline]
 __mutex_lock+0x139/0x1120 kernel/locking/mutex.c:1096
 exp_funnel_lock kernel/rcu/tree_exp.h:322 [inline]
 synchronize_rcu_expedited+0x2d5/0x620 kernel/rcu/tree_exp.h:837
 synchronize_rcu+0x132/0x190 kernel/rcu/tree.c:3765
 l2tp_session_unhash+0x374/0x550 net/l2tp/l2tp_core.c:1182
 l2tp_session_delete net/l2tp/l2tp_core.c:1551 [inline]
 l2tp_session_delete+0xaf/0x2c0 net/l2tp/l2tp_core.c:1545
 pppol2tp_release+0x264/0x560 net/l2tp/l2tp_ppp.c:450
 __sock_release+0xcd/0x280 net/socket.c:599
 sock_close+0x18/0x20 net/socket.c:1258
 __fput+0x288/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x272/0x280 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4e935ad188 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: 0000000000000085 RBX: 000000000056bf60 RCX: 0000000000466459
RDX: 0400000000000085 RSI: 0000000020000280 RDI: 0000000000000004
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffc713fe25f R14: 00007f4e935ad300 R15: 0000000000022000