============================================ WARNING: possible recursive locking detected 5.15.185-syzkaller #0 Not tainted -------------------------------------------- kworker/1:1H/1091 is trying to acquire lock: ffff8880753ced88 (&hsr->seqnr_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline] ffff8880753ced88 (&hsr->seqnr_lock){+.-.}-{2:2}, at: hsr_dev_xmit+0x130/0x1d0 net/hsr/hsr_device.c:222 but task is already holding lock: ffff888077964d88 (&hsr->seqnr_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline] ffff888077964d88 (&hsr->seqnr_lock){+.-.}-{2:2}, at: hsr_dev_xmit+0x130/0x1d0 net/hsr/hsr_device.c:222 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&hsr->seqnr_lock); lock(&hsr->seqnr_lock); *** DEADLOCK *** May be due to missing lock nesting notation 11 locks held by kworker/1:1H/1091: #0: ffff888016870d38 ((wq_completion)events_highpri){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1 #1: ffffc90005427d00 ((work_completion)(&vmidi->output_work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285 #2: ffffc90000dd0be0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:45 [inline] #2: ffffc90000dd0be0 ((&ndev->rs_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbb/0x530 kernel/time/timer.c:1441 #3: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311 #4: ffffffff8c11c000 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312 #5: ffffffff8c11c000 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312 #6: ffff888077964d88 (&hsr->seqnr_lock){+.-.}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:368 [inline] #6: ffff888077964d88 (&hsr->seqnr_lock){+.-.}-{2:2}, at: hsr_dev_xmit+0x130/0x1d0 net/hsr/hsr_device.c:222 #7: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311 #8: ffffffff8c11c000 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312 #9: ffffffff8c11bfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 include/linux/rcupdate.h:311 #10: ffffffff8c11c000 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x9/0x30 include/linux/rcupdate.h:312 stack backtrace: CPU: 1 PID: 1091 Comm: kworker/1:1H Not tainted 5.15.185-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: events_highpri snd_vmidi_output_work Call Trace: dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106 __lock_acquire+0x1227/0x7c60 kernel/locking/lockdep.c:-1 lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x32/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:368 [inline] hsr_dev_xmit+0x130/0x1d0 net/hsr/hsr_device.c:222 __netdev_start_xmit include/linux/netdevice.h:5027 [inline] netdev_start_xmit include/linux/netdevice.h:5041 [inline] xmit_one net/core/dev.c:3649 [inline] dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3665 __dev_queue_xmit+0x19df/0x2ed0 net/core/dev.c:4288 br_dev_queue_push_xmit+0x685/0x820 net/bridge/br_forward.c:53 NF_HOOK+0x2e0/0x370 include/linux/netfilter.h:302 br_forward_finish+0x74/0x80 net/bridge/br_forward.c:66 NF_HOOK+0x2e0/0x370 include/linux/netfilter.h:302 __br_forward+0x41f/0x600 net/bridge/br_forward.c:115 deliver_clone net/bridge/br_forward.c:131 [inline] maybe_deliver+0xb5/0x150 net/bridge/br_forward.c:189 br_flood+0x2fc/0x450 net/bridge/br_forward.c:231 br_dev_xmit+0xee3/0x1400 net/bridge/br_device.c:-1 __netdev_start_xmit include/linux/netdevice.h:5027 [inline] netdev_start_xmit include/linux/netdevice.h:5041 [inline] xmit_one net/core/dev.c:3649 [inline] dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3665 __dev_queue_xmit+0x19df/0x2ed0 net/core/dev.c:4288 hsr_xmit net/hsr/hsr_forward.c:338 [inline] hsr_forward_do net/hsr/hsr_forward.c:429 [inline] hsr_forward_skb+0xfb4/0x16e0 net/hsr/hsr_forward.c:582 hsr_dev_xmit+0x13b/0x1d0 net/hsr/hsr_device.c:223 __netdev_start_xmit include/linux/netdevice.h:5027 [inline] netdev_start_xmit include/linux/netdevice.h:5041 [inline] xmit_one net/core/dev.c:3649 [inline] dev_hard_start_xmit+0x2a5/0x7e0 net/core/dev.c:3665 __dev_queue_xmit+0x19df/0x2ed0 net/core/dev.c:4288 neigh_output include/net/neighbour.h:509 [inline] ip6_finish_output2+0x1070/0x1500 net/ipv6/ip6_output.c:130 dst_output include/net/dst.h:452 [inline] NF_HOOK include/linux/netfilter.h:302 [inline] ndisc_send_skb+0xbea/0x14a0 net/ipv6/ndisc.c:513 addrconf_rs_timer+0x2b8/0x600 net/ipv6/addrconf.c:3962 call_timer_fn+0x16c/0x530 kernel/time/timer.c:1451 expire_timers kernel/time/timer.c:1496 [inline] __run_timers+0x525/0x7c0 kernel/time/timer.c:1767 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1780 handle_softirqs+0x328/0x820 kernel/softirq.c:576 __do_softirq kernel/softirq.c:610 [inline] invoke_softirq kernel/softirq.c:450 [inline] __irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline] sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676 RIP: 0010:finish_lock_switch+0x134/0x280 kernel/sched/core.c:4785 Code: be ff ff ff ff e8 2c 0e 4e 08 85 c0 74 4a 4d 85 ff 75 66 e9 fe 00 00 00 48 89 df e8 26 6a 57 08 e8 21 7f 2a 00 fb 48 83 c4 08 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 99 10 fe ff 43 80 3c RSP: 0018:ffffc900054276c8 EFLAGS: 00000282 RAX: 9082f80ab2ada900 RBX: ffff8880b903a300 RCX: 9082f80ab2ada900 RDX: dffffc0000000000 RSI: ffffffff8a0b11c0 RDI: ffffffff8a59a740 RBP: 1ffff1101722760b R08: dffffc0000000000 R09: fffffbfff1ff363d R10: fffffbfff1ff363d R11: 1ffffffff1ff363c R12: ffff8880b913b048 R13: dffffc0000000000 R14: ffff8880b913adc8 R15: 0000000000000000 finish_task_switch+0x12f/0x640 kernel/sched/core.c:4902 context_switch kernel/sched/core.c:5033 [inline] __schedule+0x11c0/0x43b0 kernel/sched/core.c:6376 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:6552 preempt_schedule+0xa7/0xb0 kernel/sched/core.c:6577 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline] _raw_spin_unlock_irqrestore+0xf6/0x100 kernel/locking/spinlock.c:194 spin_unlock_irqrestore include/linux/spinlock.h:418 [inline] snd_rawmidi_transmit+0x349/0x400 sound/core/rawmidi.c:1417 snd_vmidi_output_work+0x1a0/0x400 sound/core/seq/seq_virmidi.c:151 process_one_work+0x863/0x1000 kernel/workqueue.c:2310 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457 kthread+0x436/0x520 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 ---------------- Code disassembly (best guess): 0: be ff ff ff ff mov $0xffffffff,%esi 5: e8 2c 0e 4e 08 call 0x84e0e36 a: 85 c0 test %eax,%eax c: 74 4a je 0x58 e: 4d 85 ff test %r15,%r15 11: 75 66 jne 0x79 13: e9 fe 00 00 00 jmp 0x116 18: 48 89 df mov %rbx,%rdi 1b: e8 26 6a 57 08 call 0x8576a46 20: e8 21 7f 2a 00 call 0x2a7f46 25: fb sti 26: 48 83 c4 08 add $0x8,%rsp * 2a: 5b pop %rbx <-- trapping instruction 2b: 41 5c pop %r12 2d: 41 5d pop %r13 2f: 41 5e pop %r14 31: 41 5f pop %r15 33: 5d pop %rbp 34: c3 ret 35: 48 89 df mov %rbx,%rdi 38: e8 99 10 fe ff call 0xfffe10d6 3d: 43 rex.XB 3e: 80 .byte 0x80 3f: 3c .byte 0x3c