====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.3056/17333 is trying to acquire lock: ffff888078bb8f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff888078bb8f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: hsr_dev_xmit+0x237/0x360 net/hsr/hsr_device.c:235 but task is already holding lock: ffff888057d14558 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff888057d14558 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4709 [inline] ffff888057d14558 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: sch_direct_xmit+0x153/0x4b0 net/sched/sch_generic.c:345 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}: __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] __netif_tx_lock include/linux/netdevice.h:4709 [inline] sch_direct_xmit+0x153/0x4b0 net/sched/sch_generic.c:345 __dev_xmit_skb net/core/dev.c:4169 [inline] __dev_queue_xmit+0x136f/0x3140 net/core/dev.c:4783 dev_queue_xmit include/linux/netdevice.h:3381 [inline] hsr_xmit net/hsr/hsr_forward.c:440 [inline] hsr_forward_do net/hsr/hsr_forward.c:581 [inline] hsr_forward_skb+0x158b/0x2860 net/hsr/hsr_forward.c:743 hsr_dev_xmit+0x242/0x360 net/hsr/hsr_device.c:236 __netdev_start_xmit include/linux/netdevice.h:5272 [inline] netdev_start_xmit include/linux/netdevice.h:5281 [inline] xmit_one net/core/dev.c:3853 [inline] dev_hard_start_xmit+0x2cd/0x800 net/core/dev.c:3869 __dev_queue_xmit+0x1493/0x3140 net/core/dev.c:4817 neigh_output include/net/neighbour.h:556 [inline] ip6_finish_output2+0xfb3/0x1480 net/ipv6/ip6_output.c:136 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247 NF_HOOK include/linux/netfilter.h:318 [inline] ndisc_send_skb+0xbce/0x1510 net/ipv6/ndisc.c:512 ndisc_send_ns+0xcb/0x150 net/ipv6/ndisc.c:670 addrconf_dad_work+0xaae/0x14b0 net/ipv6/addrconf.c:4282 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 -> #0 (&hsr->seqnr_lock){+.-.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x36/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] hsr_dev_xmit+0x237/0x360 net/hsr/hsr_device.c:235 __netdev_start_xmit include/linux/netdevice.h:5272 [inline] netdev_start_xmit include/linux/netdevice.h:5281 [inline] xmit_one net/core/dev.c:3853 [inline] dev_hard_start_xmit+0x2cd/0x800 net/core/dev.c:3869 __dev_queue_xmit+0x1493/0x3140 net/core/dev.c:4817 NF_HOOK+0x310/0x3a0 include/linux/netfilter.h:-1 arp_xmit+0x16c/0x270 net/ipv4/arp.c:664 arp_solicit+0xc1d/0xe60 net/ipv4/arp.c:392 neigh_probe net/core/neighbour.c:1097 [inline] __neigh_event_send+0xf3e/0x1520 net/core/neighbour.c:1270 neigh_event_send_probe include/net/neighbour.h:480 [inline] neigh_event_send include/net/neighbour.h:486 [inline] neigh_resolve_output+0x198/0x750 net/core/neighbour.c:1578 neigh_output include/net/neighbour.h:556 [inline] ip_finish_output2+0xd40/0x1160 net/ipv4/ip_output.c:237 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip_output+0x29f/0x450 net/ipv4/ip_output.c:438 iptunnel_xmit+0x5f8/0xa90 net/ipv4/ip_tunnel_core.c:84 ip_tunnel_xmit+0x1c41/0x2390 net/ipv4/ip_tunnel.c:845 __gre_xmit net/ipv4/ip_gre.c:488 [inline] gre_tap_xmit+0x590/0x7a0 net/ipv4/ip_gre.c:776 __netdev_start_xmit include/linux/netdevice.h:5272 [inline] netdev_start_xmit include/linux/netdevice.h:5281 [inline] xmit_one net/core/dev.c:3853 [inline] dev_hard_start_xmit+0x2cd/0x800 net/core/dev.c:3869 sch_direct_xmit+0x241/0x4b0 net/sched/sch_generic.c:347 __dev_xmit_skb net/core/dev.c:4169 [inline] __dev_queue_xmit+0x136f/0x3140 net/core/dev.c:4783 neigh_output include/net/neighbour.h:556 [inline] ip_finish_output2+0xd40/0x1160 net/ipv4/ip_output.c:237 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip_output+0x29f/0x450 net/ipv4/ip_output.c:438 ip_local_out net/ipv4/ip_output.c:131 [inline] ip_send_skb+0x74/0x100 net/ipv4/ip_output.c:1508 udp_send_skb+0xaf1/0x14c0 net/ipv4/udp.c:1195 udp_sendmsg+0x195a/0x2170 net/ipv4/udp.c:1484 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg+0x19c/0x270 net/socket.c:733 ____sys_sendmsg+0x52d/0x820 net/socket.c:2608 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2662 __sys_sendmmsg+0x227/0x430 net/socket.c:2751 __do_sys_sendmmsg net/socket.c:2778 [inline] __se_sys_sendmmsg net/socket.c:2775 [inline] __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2775 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&qdisc_xmit_lock_key#4); lock(&hsr->seqnr_lock); lock(&qdisc_xmit_lock_key#4); lock(&hsr->seqnr_lock); *** DEADLOCK *** 10 locks held by syz.0.3056/17333: #0: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #0: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #0: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: ip_output+0x5b/0x450 net/ipv4/ip_output.c:433 #1: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #1: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #1: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: ip_finish_output2+0x452/0x1160 net/ipv4/ip_output.c:230 #2: ffffffff8df41d20 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #2: ffffffff8df41d20 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:918 [inline] #2: ffffffff8df41d20 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x289/0x3140 net/core/dev.c:4742 #3: ffff88802eccb228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: spin_trylock include/linux/spinlock.h:361 [inline] #3: ffff88802eccb228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: qdisc_run_begin include/net/sch_generic.h:202 [inline] #3: ffff88802eccb228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: __dev_xmit_skb net/core/dev.c:4156 [inline] #3: ffff88802eccb228 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock#3){+...}-{3:3}, at: __dev_queue_xmit+0xeb4/0x3140 net/core/dev.c:4783 #4: ffff888057d14558 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] #4: ffff888057d14558 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: __netif_tx_lock include/linux/netdevice.h:4709 [inline] #4: ffff888057d14558 (&qdisc_xmit_lock_key#4){+.-.}-{3:3}, at: sch_direct_xmit+0x153/0x4b0 net/sched/sch_generic.c:345 #5: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #5: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #5: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: ip_output+0x5b/0x450 net/ipv4/ip_output.c:433 #6: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #6: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #6: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: ip_finish_output2+0x452/0x1160 net/ipv4/ip_output.c:230 #7: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #7: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #7: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: arp_xmit+0x23/0x270 net/ipv4/arp.c:662 #8: ffffffff8df41d20 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #8: ffffffff8df41d20 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:918 [inline] #8: ffffffff8df41d20 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x289/0x3140 net/core/dev.c:4742 #9: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #9: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline] #9: ffffffff8df41cc0 (rcu_read_lock){....}-{1:3}, at: hsr_dev_xmit+0x2d/0x360 net/hsr/hsr_device.c:229 stack backtrace: CPU: 0 UID: 0 PID: 17333 Comm: syz.0.3056 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x117/0x340 kernel/locking/lockdep.c:5868 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x36/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] hsr_dev_xmit+0x237/0x360 net/hsr/hsr_device.c:235 __netdev_start_xmit include/linux/netdevice.h:5272 [inline] netdev_start_xmit include/linux/netdevice.h:5281 [inline] xmit_one net/core/dev.c:3853 [inline] dev_hard_start_xmit+0x2cd/0x800 net/core/dev.c:3869 __dev_queue_xmit+0x1493/0x3140 net/core/dev.c:4817 NF_HOOK+0x310/0x3a0 include/linux/netfilter.h:-1 arp_xmit+0x16c/0x270 net/ipv4/arp.c:664 arp_solicit+0xc1d/0xe60 net/ipv4/arp.c:392 neigh_probe net/core/neighbour.c:1097 [inline] __neigh_event_send+0xf3e/0x1520 net/core/neighbour.c:1270 neigh_event_send_probe include/net/neighbour.h:480 [inline] neigh_event_send include/net/neighbour.h:486 [inline] neigh_resolve_output+0x198/0x750 net/core/neighbour.c:1578 neigh_output include/net/neighbour.h:556 [inline] ip_finish_output2+0xd40/0x1160 net/ipv4/ip_output.c:237 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip_output+0x29f/0x450 net/ipv4/ip_output.c:438 iptunnel_xmit+0x5f8/0xa90 net/ipv4/ip_tunnel_core.c:84 ip_tunnel_xmit+0x1c41/0x2390 net/ipv4/ip_tunnel.c:845 __gre_xmit net/ipv4/ip_gre.c:488 [inline] gre_tap_xmit+0x590/0x7a0 net/ipv4/ip_gre.c:776 __netdev_start_xmit include/linux/netdevice.h:5272 [inline] netdev_start_xmit include/linux/netdevice.h:5281 [inline] xmit_one net/core/dev.c:3853 [inline] dev_hard_start_xmit+0x2cd/0x800 net/core/dev.c:3869 sch_direct_xmit+0x241/0x4b0 net/sched/sch_generic.c:347 __dev_xmit_skb net/core/dev.c:4169 [inline] __dev_queue_xmit+0x136f/0x3140 net/core/dev.c:4783 neigh_output include/net/neighbour.h:556 [inline] ip_finish_output2+0xd40/0x1160 net/ipv4/ip_output.c:237 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip_output+0x29f/0x450 net/ipv4/ip_output.c:438 ip_local_out net/ipv4/ip_output.c:131 [inline] ip_send_skb+0x74/0x100 net/ipv4/ip_output.c:1508 udp_send_skb+0xaf1/0x14c0 net/ipv4/udp.c:1195 udp_sendmsg+0x195a/0x2170 net/ipv4/udp.c:1484 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg+0x19c/0x270 net/socket.c:733 ____sys_sendmsg+0x52d/0x820 net/socket.c:2608 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2662 __sys_sendmmsg+0x227/0x430 net/socket.c:2751 __do_sys_sendmmsg net/socket.c:2778 [inline] __se_sys_sendmmsg net/socket.c:2775 [inline] __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2775 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f15bad8f749 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:00007f15bbc71038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f15bafe5fa0 RCX: 00007f15bad8f749 RDX: 0000000000000001 RSI: 0000200000003380 RDI: 0000000000000009 RBP: 00007f15bae13f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000004040880 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f15bafe6038 R14: 00007f15bafe5fa0 R15: 00007ffd63e501f8