===================================== WARNING: bad unlock balance detected! 5.5.0-rc5-syzkaller #0 Not tainted ------------------------------------- syz-executor.4/9561 is trying to release lock (&dev->qdisc_xmit_lock_key) at: [] spin_unlock include/linux/spinlock.h:378 [inline] [] __netif_tx_unlock include/linux/netdevice.h:3966 [inline] [] sch_direct_xmit+0x3fa/0xd30 net/sched/sch_generic.c:315 but there are no more locks to release! other info that might help us debug this: 4 locks held by syz-executor.4/9561: #0: ffffc90000007d50 ((&n->timer)){+.-.}, at: lockdep_copy_map include/linux/lockdep.h:172 [inline] #0: ffffc90000007d50 ((&n->timer)){+.-.}, at: call_timer_fn+0xe0/0x780 kernel/time/timer.c:1394 #1: ffffffff899a3ec0 (rcu_read_lock_bh){....}, at: __dev_queue_xmit+0x20a/0x35c0 net/core/dev.c:3948 #2: ffff8880908e3250 (&dev->qdisc_tx_busylock_key#25){+...}, at: spin_trylock include/linux/spinlock.h:348 [inline] #2: ffff8880908e3250 (&dev->qdisc_tx_busylock_key#25){+...}, at: qdisc_run_begin include/net/sch_generic.h:159 [inline] #2: ffff8880908e3250 (&dev->qdisc_tx_busylock_key#25){+...}, at: __dev_xmit_skb net/core/dev.c:3611 [inline] #2: ffff8880908e3250 (&dev->qdisc_tx_busylock_key#25){+...}, at: __dev_queue_xmit+0x2412/0x35c0 net/core/dev.c:3982 #3: ffff8880908e3138 (&dev->qdisc_running_key#25){+...}, at: dev_queue_xmit+0x18/0x20 net/core/dev.c:4046 stack backtrace: CPU: 0 PID: 9561 Comm: syz-executor.4 Not tainted 5.5.0-rc5-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+0x197/0x210 lib/dump_stack.c:118 print_unlock_imbalance_bug kernel/locking/lockdep.c:4008 [inline] print_unlock_imbalance_bug.cold+0x114/0x123 kernel/locking/lockdep.c:3984 __lock_release kernel/locking/lockdep.c:4242 [inline] lock_release+0x5f2/0x960 kernel/locking/lockdep.c:4503 __raw_spin_unlock include/linux/spinlock_api_smp.h:150 [inline] _raw_spin_unlock+0x16/0x40 kernel/locking/spinlock.c:183 spin_unlock include/linux/spinlock.h:378 [inline] __netif_tx_unlock include/linux/netdevice.h:3966 [inline] sch_direct_xmit+0x3fa/0xd30 net/sched/sch_generic.c:315 __dev_xmit_skb net/core/dev.c:3621 [inline] __dev_queue_xmit+0x2707/0x35c0 net/core/dev.c:3982 dev_queue_xmit+0x18/0x20 net/core/dev.c:4046 arp_xmit_finish net/ipv4/arp.c:630 [inline] NF_HOOK include/linux/netfilter.h:307 [inline] NF_HOOK include/linux/netfilter.h:301 [inline] arp_xmit+0xdf/0x3f0 net/ipv4/arp.c:639 arp_send_dst.part.0+0x202/0x290 net/ipv4/arp.c:317 arp_send_dst net/ipv4/arp.c:390 [inline] arp_solicit+0x748/0x1370 net/ipv4/arp.c:389 neigh_probe+0xd0/0x120 net/core/neighbour.c:1009 neigh_timer_handler+0x59d/0x10e0 net/core/neighbour.c:1090 call_timer_fn+0x1ac/0x780 kernel/time/timer.c:1404 expire_timers kernel/time/timer.c:1449 [inline] __run_timers kernel/time/timer.c:1773 [inline] __run_timers kernel/time/timer.c:1740 [inline] run_timer_softirq+0x6c3/0x1790 kernel/time/timer.c:1786 __do_softirq+0x262/0x98c kernel/softirq.c:292 invoke_softirq kernel/softirq.c:373 [inline] irq_exit+0x19b/0x1e0 kernel/softirq.c:413 exiting_irq arch/x86/include/asm/apic.h:536 [inline] smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1137 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829 RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline] RIP: 0010:_raw_spin_unlock_irq+0x4f/0x80 kernel/locking/spinlock.c:199 Code: c0 e8 34 93 89 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 03 80 3c 10 00 75 33 48 83 3d 02 f4 be 01 00 74 20 fb 66 0f 1f 44 00 00 01 00 00 00 e8 97 49 7c f9 65 8b 05 88 dd 2d 78 85 c0 74 06 41 RSP: 0018:ffffc900021179d8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 RAX: 1ffffffff132669d RBX: ffff8880658fc500 RCX: 0000000000000000 RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880658fcd94 RBP: ffffc900021179e0 R08: ffff8880658fc500 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880ae837340 R13: ffff888060e26340 R14: 0000000000000000 R15: 0000000000000001 finish_lock_switch kernel/sched/core.c:3124 [inline] finish_task_switch+0x147/0x750 kernel/sched/core.c:3224 context_switch kernel/sched/core.c:3388 [inline] __schedule+0x93c/0x1f90 kernel/sched/core.c:4081 preempt_schedule_common+0x4f/0xe0 kernel/sched/core.c:4236 preempt_schedule+0x4b/0x60 kernel/sched/core.c:4261 ___preempt_schedule+0x16/0x18 arch/x86/entry/thunk_64.S:50 __raw_read_unlock include/linux/rwlock_api_smp.h:227 [inline] _raw_read_unlock+0x3c/0x40 kernel/locking/spinlock.c:255 do_wait+0x594/0xa10 kernel/exit.c:1456 kernel_wait4+0x171/0x290 kernel/exit.c:1617 __do_sys_wait4+0x147/0x160 kernel/exit.c:1629 __se_sys_wait4 kernel/exit.c:1625 [inline] __x64_sys_wait4+0x97/0xf0 kernel/exit.c:1625 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x414d8a Code: 0f 83 6a 18 00 00 c3 66 0f 1f 84 00 00 00 00 00 8b 05 ee 36 66 00 85 c0 75 36 45 31 d2 48 63 d2 48 63 ff b8 3d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 06 c3 0f 1f 44 00 00 48 c7 c2 d4 ff ff ff f7 RSP: 002b:00007ffe33e559e8 EFLAGS: 00000246 ORIG_RAX: 000000000000003d RAX: ffffffffffffffda RBX: 00000000001861e2 RCX: 0000000000414d8a RDX: 0000000040000001 RSI: 00007ffe33e55a20 RDI: ffffffffffffffff RBP: 0000000000001891 R08: 0000000000000001 R09: 0000000001c00940 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ffe33e55a20 R14: 00000000001861cc R15: 00007ffe33e55a30