============================================ WARNING: possible recursive locking detected 5.8.0-rc2-syzkaller #0 Not tainted -------------------------------------------- syz-executor.2/22318 is trying to acquire lock: ffff88805c974280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: netif_addr_lock_nested include/linux/netdevice.h:4251 [inline] ffff88805c974280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_mc_unsync net/core/dev_addr_lists.c:915 [inline] ffff88805c974280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_mc_unsync+0xf4/0x190 net/core/dev_addr_lists.c:909 but task is already holding lock: ffff88805ee34280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:358 [inline] ffff88805ee34280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: netif_addr_lock_bh include/linux/netdevice.h:4256 [inline] ffff88805ee34280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_mc_unsync net/core/dev_addr_lists.c:914 [inline] ffff88805ee34280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_mc_unsync+0xb0/0x190 net/core/dev_addr_lists.c:909 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&vlan_netdev_addr_lock_key/1); lock(&vlan_netdev_addr_lock_key/1); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz-executor.2/22318: #0: ffffffff8a799948 (vlan_ioctl_mutex){+.+.}-{3:3}, at: sock_ioctl+0x4b8/0x730 net/socket.c:1155 #1: ffffffff8a7b18e8 (rtnl_mutex){+.+.}-{3:3}, at: vlan_ioctl_handler+0xb7/0xeed net/8021q/vlan.c:554 #2: ffff88805ee34280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:358 [inline] #2: ffff88805ee34280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: netif_addr_lock_bh include/linux/netdevice.h:4256 [inline] #2: ffff88805ee34280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_mc_unsync net/core/dev_addr_lists.c:914 [inline] #2: ffff88805ee34280 (&vlan_netdev_addr_lock_key/1){+...}-{2:2}, at: dev_mc_unsync+0xb0/0x190 net/core/dev_addr_lists.c:909 stack backtrace: CPU: 1 PID: 22318 Comm: syz-executor.2 Not tainted 5.8.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 print_deadlock_bug kernel/locking/lockdep.c:2391 [inline] check_deadlock kernel/locking/lockdep.c:2432 [inline] validate_chain kernel/locking/lockdep.c:3202 [inline] __lock_acquire.cold+0x178/0x3f8 kernel/locking/lockdep.c:4380 lock_acquire+0x1f1/0xad0 kernel/locking/lockdep.c:4959 _raw_spin_lock_nested+0x30/0x40 kernel/locking/spinlock.c:361 netif_addr_lock_nested include/linux/netdevice.h:4251 [inline] dev_mc_unsync net/core/dev_addr_lists.c:915 [inline] dev_mc_unsync+0xf4/0x190 net/core/dev_addr_lists.c:909 vlan_dev_stop+0x51/0x350 net/8021q/vlan_dev.c:315 __dev_close_many+0x1b3/0x2e0 net/core/dev.c:1605 dev_close_many+0x238/0x650 net/core/dev.c:1630 vlan_device_event+0x8ef/0x2010 net/8021q/vlan.c:450 notifier_call_chain+0xb5/0x200 kernel/notifier.c:83 call_netdevice_notifiers_info+0xb5/0x130 net/core/dev.c:2033 call_netdevice_notifiers_extack net/core/dev.c:2045 [inline] call_netdevice_notifiers net/core/dev.c:2059 [inline] dev_close_many+0x30b/0x650 net/core/dev.c:1634 rollback_registered_many+0x3af/0xf60 net/core/dev.c:8953 rollback_registered net/core/dev.c:9021 [inline] unregister_netdevice_queue+0x2dd/0x570 net/core/dev.c:10102 unregister_vlan_dev+0x2c0/0x570 net/8021q/vlan.c:111 vlan_ioctl_handler+0x311/0xeed net/8021q/vlan.c:629 sock_ioctl+0x4d1/0x730 net/socket.c:1157 vfs_ioctl fs/ioctl.c:48 [inline] ksys_ioctl+0x11a/0x180 fs/ioctl.c:753 __do_sys_ioctl fs/ioctl.c:762 [inline] __se_sys_ioctl fs/ioctl.c:760 [inline] __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45cba9 Code: Bad RIP value. RSP: 002b:00007f74ce359c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000004f4740 RCX: 000000000045cba9 RDX: 0000000020000040 RSI: 0000000000008983 RDI: 0000000000000005 RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000000006a9 R14: 00000000004d57c0 R15: 00007f74ce35a6d4