Warning: Permanently added '10.128.15.231' (ECDSA) to the list of known hosts.
executing program
[   39.622388][ T5923] 
[   39.622916][ T5923] ============================================
[   39.624351][ T5923] WARNING: possible recursive locking detected
[   39.625805][ T5923] 6.2.0-syzkaller-18300-g2ebd1fbb946d #0 Not tainted
[   39.627401][ T5923] --------------------------------------------
[   39.628837][ T5923] syz-executor219/5923 is trying to acquire lock:
[   39.630335][ T5923] ffff0000c140c130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: l2tp_tunnel_register+0x888/0x19f8
[   39.632581][ T5923] 
[   39.632581][ T5923] but task is already holding lock:
[   39.634466][ T5923] ffff0000cbfdf130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppol2tp_connect+0x53c/0x1348
[   39.636538][ T5923] 
[   39.636538][ T5923] other info that might help us debug this:
[   39.638243][ T5923]  Possible unsafe locking scenario:
[   39.638243][ T5923] 
[   39.639870][ T5923]        CPU0
[   39.640554][ T5923]        ----
[   39.641201][ T5923]   lock(sk_lock-AF_PPPOX);
[   39.642168][ T5923]   lock(sk_lock-AF_PPPOX);
[   39.643206][ T5923] 
[   39.643206][ T5923]  *** DEADLOCK ***
[   39.643206][ T5923] 
[   39.644976][ T5923]  May be due to missing lock nesting notation
[   39.644976][ T5923] 
[   39.646692][ T5923] 1 lock held by syz-executor219/5923:
[   39.647877][ T5923]  #0: ffff0000cbfdf130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppol2tp_connect+0x53c/0x1348
[   39.650099][ T5923] 
[   39.650099][ T5923] stack backtrace:
[   39.651386][ T5923] CPU: 0 PID: 5923 Comm: syz-executor219 Not tainted 6.2.0-syzkaller-18300-g2ebd1fbb946d #0
[   39.653528][ T5923] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023
[   39.655662][ T5923] Call trace:
[   39.656354][ T5923]  dump_backtrace+0x1c8/0x1f4
[   39.657369][ T5923]  show_stack+0x2c/0x3c
[   39.658236][ T5923]  dump_stack_lvl+0xd0/0x124
[   39.659253][ T5923]  dump_stack+0x1c/0x28
[   39.660198][ T5923]  __lock_acquire+0x6310/0x764c
[   39.661322][ T5923]  lock_acquire+0x2e8/0x8c0
[   39.662297][ T5923]  lock_sock_nested+0x78/0x138
[   39.663372][ T5923]  l2tp_tunnel_register+0x888/0x19f8
[   39.664553][ T5923]  pppol2tp_connect+0x944/0x1348
[   39.665621][ T5923]  __sys_connect+0x268/0x290
[   39.666630][ T5923]  __arm64_sys_connect+0x7c/0x94
[   39.667742][ T5923]  invoke_syscall+0x98/0x2c0
[   39.668715][ T5923]  el0_svc_common+0x138/0x258
[   39.669747][ T5923]  do_el0_svc+0x64/0x198
[   39.670719][ T5923]  el0_svc+0x58/0x168
[   39.671648][ T5923]  el0t_64_sync_handler+0x84/0xf0
[   39.672714][ T5923]  el0t_64_sync+0x190/0x194