====================================================== WARNING: possible circular locking dependency detected 6.1.123-syzkaller #0 Not tainted ------------------------------------------------------ syz.0.954/8136 is trying to acquire lock: ffffffff8e653238 (nr_neigh_list_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffffffff8e653238 (nr_neigh_list_lock){+...}-{2:2}, at: nr_remove_neigh+0x25/0xe0 net/netrom/nr_route.c:307 but task is already holding lock: ffff888019aca970 (&nr_node->node_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff888019aca970 (&nr_node->node_lock){+...}-{2:2}, at: nr_node_lock include/net/netrom.h:152 [inline] ffff888019aca970 (&nr_node->node_lock){+...}-{2:2}, at: nr_add_node+0xfc0/0x2210 net/netrom/nr_route.c:214 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&nr_node->node_lock){+...}-{2:2}: lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] nr_node_lock include/net/netrom.h:152 [inline] nr_rt_device_down+0x155/0x7b0 net/netrom/nr_route.c:519 nr_device_event+0x12b/0x140 net/netrom/af_netrom.c:126 notifier_call_chain kernel/notifier.c:87 [inline] raw_notifier_call_chain+0xd0/0x170 kernel/notifier.c:455 __dev_notify_flags+0x304/0x610 dev_change_flags+0xe7/0x190 net/core/dev.c:8669 dev_ifsioc+0x177/0x1160 net/core/dev_ioctl.c:327 dev_ioctl+0x508/0xf70 net/core/dev_ioctl.c:588 sock_do_ioctl+0x26b/0x450 net/socket.c:1218 sock_ioctl+0x47f/0x770 net/socket.c:1321 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #1 (nr_node_list_lock){+...}-{2:2}: lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] nr_rt_device_down+0xb1/0x7b0 net/netrom/nr_route.c:517 nr_device_event+0x12b/0x140 net/netrom/af_netrom.c:126 notifier_call_chain kernel/notifier.c:87 [inline] raw_notifier_call_chain+0xd0/0x170 kernel/notifier.c:455 __dev_notify_flags+0x304/0x610 dev_change_flags+0xe7/0x190 net/core/dev.c:8669 dev_ifsioc+0x177/0x1160 net/core/dev_ioctl.c:327 dev_ioctl+0x508/0xf70 net/core/dev_ioctl.c:588 sock_do_ioctl+0x26b/0x450 net/socket.c:1218 sock_ioctl+0x47f/0x770 net/socket.c:1321 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 -> #0 (nr_neigh_list_lock){+...}-{2:2}: check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] nr_remove_neigh+0x25/0xe0 net/netrom/nr_route.c:307 nr_add_node+0x14fd/0x2210 net/netrom/nr_route.c:249 nr_rt_ioctl+0xd38/0xfb0 net/netrom/nr_route.c:651 sock_do_ioctl+0x152/0x450 net/socket.c:1204 sock_ioctl+0x47f/0x770 net/socket.c:1321 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 other info that might help us debug this: Chain exists of: nr_neigh_list_lock --> nr_node_list_lock --> &nr_node->node_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&nr_node->node_lock); lock(nr_node_list_lock); lock(&nr_node->node_lock); lock(nr_neigh_list_lock); *** DEADLOCK *** 1 lock held by syz.0.954/8136: #0: ffff888019aca970 (&nr_node->node_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] #0: ffff888019aca970 (&nr_node->node_lock){+...}-{2:2}, at: nr_node_lock include/net/netrom.h:152 [inline] #0: ffff888019aca970 (&nr_node->node_lock){+...}-{2:2}, at: nr_add_node+0xfc0/0x2210 net/netrom/nr_route.c:214 stack backtrace: CPU: 1 PID: 8136 Comm: syz.0.954 Not tainted 6.1.123-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2170 check_prev_add kernel/locking/lockdep.c:3090 [inline] check_prevs_add kernel/locking/lockdep.c:3209 [inline] validate_chain+0x1661/0x5950 kernel/locking/lockdep.c:3825 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5049 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5662 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] nr_remove_neigh+0x25/0xe0 net/netrom/nr_route.c:307 nr_add_node+0x14fd/0x2210 net/netrom/nr_route.c:249 nr_rt_ioctl+0xd38/0xfb0 net/netrom/nr_route.c:651 sock_do_ioctl+0x152/0x450 net/socket.c:1204 sock_ioctl+0x47f/0x770 net/socket.c:1321 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f3032585d29 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f3033448038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f3032775fa0 RCX: 00007f3032585d29 RDX: 0000000020000000 RSI: 000000000000890b RDI: 0000000000000004 RBP: 00007f3032601b08 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f3032775fa0 R15: 00007fffb903ad38