====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc1-syzkaller-00412-g4e34a840613b #0 Not tainted ------------------------------------------------------ kworker/0:1/700 is trying to acquire lock: ffff8880622014c0 (&br->multicast_lock){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff8880622014c0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_add_group net/bridge/br_multicast.c:1568 [inline] ffff8880622014c0 (&br->multicast_lock){+.-.}-{3:3}, at: br_ip6_multicast_add_group net/bridge/br_multicast.c:1621 [inline] ffff8880622014c0 (&br->multicast_lock){+.-.}-{3:3}, at: br_ip6_multicast_mld2_report net/bridge/br_multicast.c:2976 [inline] ffff8880622014c0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_ipv6_rcv net/bridge/br_multicast.c:3914 [inline] ffff8880622014c0 (&br->multicast_lock){+.-.}-{3:3}, at: br_multicast_rcv+0x4015/0x7f60 net/bridge/br_multicast.c:3972 but task is already holding lock: ffff8880330f0f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] ffff8880330f0f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: hsr_dev_xmit+0x18a/0x210 net/hsr/hsr_device.c:234 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&hsr->seqnr_lock){+.-.}-{3:3}: lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline] _raw_spin_lock_bh+0x35/0x50 kernel/locking/spinlock.c:178 spin_lock_bh include/linux/spinlock.h:356 [inline] hsr_dev_xmit+0x18a/0x210 net/hsr/hsr_device.c:234 __netdev_start_xmit include/linux/netdevice.h:5203 [inline] netdev_start_xmit include/linux/netdevice.h:5212 [inline] xmit_one net/core/dev.c:3826 [inline] dev_hard_start_xmit+0x2d9/0x830 net/core/dev.c:3842 __dev_queue_xmit+0x1b80/0x3f60 net/core/dev.c:4679 dev_queue_xmit include/linux/netdevice.h:3349 [inline] br_dev_queue_push_xmit+0x771/0x950 net/bridge/br_forward.c:53 NF_HOOK include/linux/netfilter.h:314 [inline] __br_multicast_send_query+0x2fcd/0x4830 net/bridge/br_multicast.c:1809 br_multicast_send_query+0x4f2/0x6c0 net/bridge/br_multicast.c:1888 br_multicast_port_query_expired+0x2d4/0x3b0 net/bridge/br_multicast.c:1913 call_timer_fn+0x189/0x650 kernel/time/timer.c:1789 expire_timers kernel/time/timer.c:1840 [inline] __run_timers kernel/time/timer.c:2414 [inline] __run_timer_base+0x66e/0x8e0 kernel/time/timer.c:2426 run_timer_base kernel/time/timer.c:2435 [inline] run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2445 handle_softirqs+0x2d6/0x9b0 kernel/softirq.c:579 __do_softirq kernel/softirq.c:613 [inline] invoke_softirq kernel/softirq.c:453 [inline] __irq_exit_rcu+0xfb/0x220 kernel/softirq.c:680 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1049 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 console_flush_all+0x998/0xec0 arch/x86/include/asm/irqflags.h:-1 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline] console_unlock+0x151/0x3b0 kernel/printk/printk.c:3325 vprintk_emit+0x761/0xa40 kernel/printk/printk.c:2450 _printk+0xd5/0x120 kernel/printk/printk.c:2475 br_multicast_set_startup_query_intvl+0xe2/0xf0 net/bridge/br_multicast.c:4733 br_changelink+0xfff/0x1810 net/bridge/br_netlink.c:1486 rtnl_changelink net/core/rtnetlink.c:3733 [inline] __rtnl_newlink net/core/rtnetlink.c:3932 [inline] rtnl_newlink+0x1842/0x1fe0 net/core/rtnetlink.c:4069 rtnetlink_rcv_msg+0x80f/0xd70 net/core/rtnetlink.c:6959 netlink_rcv_skb+0x208/0x480 net/netlink/af_netlink.c:2534 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline] netlink_unicast+0x7f8/0x9a0 net/netlink/af_netlink.c:1339 netlink_sendmsg+0x8c3/0xcd0 net/netlink/af_netlink.c:1883 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:727 ____sys_sendmsg+0x523/0x860 net/socket.c:2566 ___sys_sendmsg net/socket.c:2620 [inline] __sys_sendmsg+0x271/0x360 net/socket.c:2652 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&br->multicast_lock){+.-.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain+0xa69/0x24e0 kernel/locking/lockdep.c:3909 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235 lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 __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] br_multicast_add_group net/bridge/br_multicast.c:1568 [inline] br_ip6_multicast_add_group net/bridge/br_multicast.c:1621 [inline] br_ip6_multicast_mld2_report net/bridge/br_multicast.c:2976 [inline] br_multicast_ipv6_rcv net/bridge/br_multicast.c:3914 [inline] br_multicast_rcv+0x4015/0x7f60 net/bridge/br_multicast.c:3972 br_dev_xmit+0xbbc/0x1c00 net/bridge/br_device.c:98 __netdev_start_xmit include/linux/netdevice.h:5203 [inline] netdev_start_xmit include/linux/netdevice.h:5212 [inline] xmit_one net/core/dev.c:3826 [inline] dev_hard_start_xmit+0x2d9/0x830 net/core/dev.c:3842 __dev_queue_xmit+0x1b80/0x3f60 net/core/dev.c:4679 __bond_start_xmit include/linux/netdevice.h:-1 [inline] bond_start_xmit+0x138e/0x1c50 drivers/net/bonding/bond_main.c:5599 __netdev_start_xmit include/linux/netdevice.h:5203 [inline] netdev_start_xmit include/linux/netdevice.h:5212 [inline] xmit_one net/core/dev.c:3826 [inline] dev_hard_start_xmit+0x2d9/0x830 net/core/dev.c:3842 sch_direct_xmit+0x2b2/0x600 net/sched/sch_generic.c:343 qdisc_restart net/sched/sch_generic.c:408 [inline] __qdisc_run+0xc0d/0x2180 net/sched/sch_generic.c:416 __dev_xmit_skb net/core/dev.c:4137 [inline] __dev_queue_xmit+0x10e2/0x3f60 net/core/dev.c:4645 dev_queue_xmit include/linux/netdevice.h:3349 [inline] hsr_xmit net/hsr/hsr_forward.c:430 [inline] hsr_forward_do net/hsr/hsr_forward.c:571 [inline] hsr_forward_skb+0x184c/0x2d20 net/hsr/hsr_forward.c:733 hsr_dev_xmit+0x195/0x210 net/hsr/hsr_device.c:235 __netdev_start_xmit include/linux/netdevice.h:5203 [inline] netdev_start_xmit include/linux/netdevice.h:5212 [inline] xmit_one net/core/dev.c:3826 [inline] dev_hard_start_xmit+0x2d9/0x830 net/core/dev.c:3842 __dev_queue_xmit+0x1b80/0x3f60 net/core/dev.c:4679 neigh_output include/net/neighbour.h:539 [inline] ip6_finish_output2+0x1296/0x1750 net/ipv6/ip6_output.c:141 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline] ip6_finish_output+0x421/0x840 net/ipv6/ip6_output.c:226 NF_HOOK+0xa0/0x440 include/linux/netfilter.h:314 mld_sendpack+0x84a/0xdc0 net/ipv6/mcast.c:1868 mld_dad_work+0x44/0x500 net/ipv6/mcast.c:2308 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xac3/0x18e0 kernel/workqueue.c:3319 worker_thread+0x870/0xd50 kernel/workqueue.c:3400 kthread+0x7b7/0x940 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&hsr->seqnr_lock); lock(&br->multicast_lock); lock(&hsr->seqnr_lock); lock(&br->multicast_lock); *** DEADLOCK *** 12 locks held by kworker/0:1/700: #0: ffff8880305fbd48 ((wq_completion)mld){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3213 [inline] #0: ffff8880305fbd48 ((wq_completion)mld){+.+.}-{0:0}, at: process_scheduled_works+0x990/0x18e0 kernel/workqueue.c:3319 #1: ffffc9000b67fc60 ((work_completion)(&(&idev->mc_dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline] #1: ffffc9000b67fc60 ((work_completion)(&(&idev->mc_dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9cb/0x18e0 kernel/workqueue.c:3319 #2: ffff888060325538 (&idev->mc_lock){+.+.}-{4:4}, at: mld_dad_work+0x3c/0x500 net/ipv6/mcast.c:2307 #3: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #3: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #3: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: mld_sendpack+0x1ea/0xdc0 net/ipv6/mcast.c:1840 #4: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #4: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #4: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: ip6_finish_output2+0x701/0x1750 net/ipv6/ip6_output.c:126 #5: ffffffff8ed3e040 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #5: ffffffff8ed3e040 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:892 [inline] #5: ffffffff8ed3e040 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x2f9/0x3f60 net/core/dev.c:4604 #6: ffff8880330f0f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: spin_lock_bh include/linux/spinlock.h:356 [inline] #6: ffff8880330f0f30 (&hsr->seqnr_lock){+.-.}-{3:3}, at: hsr_dev_xmit+0x18a/0x210 net/hsr/hsr_device.c:234 #7: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #7: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #7: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: hsr_forward_skb+0xb8/0x2d20 net/hsr/hsr_forward.c:728 #8: ffffffff8ed3e040 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #8: ffffffff8ed3e040 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:892 [inline] #8: ffffffff8ed3e040 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x2f9/0x3f60 net/core/dev.c:4604 #9: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #9: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #9: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: bond_start_xmit+0x12a/0x1c50 drivers/net/bonding/bond_main.c:5597 #10: ffffffff8ed3e040 (rcu_read_lock_bh){....}-{1:3}, at: local_bh_disable include/linux/bottom_half.h:20 [inline] #10: ffffffff8ed3e040 (rcu_read_lock_bh){....}-{1:3}, at: rcu_read_lock_bh include/linux/rcupdate.h:892 [inline] #10: ffffffff8ed3e040 (rcu_read_lock_bh){....}-{1:3}, at: __dev_queue_xmit+0x2f9/0x3f60 net/core/dev.c:4604 #11: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline] #11: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline] #11: ffffffff8ed3dfe0 (rcu_read_lock){....}-{1:3}, at: br_dev_xmit+0x220/0x1c00 net/bridge/br_device.c:52 stack backtrace: CPU: 0 UID: 0 PID: 700 Comm: kworker/0:1 Not tainted 6.15.0-rc1-syzkaller-00412-g4e34a840613b #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Workqueue: mld mld_dad_work Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2079 check_noncircular+0x142/0x160 kernel/locking/lockdep.c:2211 check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain+0xa69/0x24e0 kernel/locking/lockdep.c:3909 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235 lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866 __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] br_multicast_add_group net/bridge/br_multicast.c:1568 [inline] br_ip6_multicast_add_group net/bridge/br_multicast.c:1621 [inline] br_ip6_multicast_mld2_report net/bridge/br_multicast.c:2976 [inline] br_multicast_ipv6_rcv net/bridge/br_multicast.c:3914 [inline] br_multicast_rcv+0x4015/0x7f60 net/bridge/br_multicast.c:3972 br_dev_xmit+0xbbc/0x1c00 net/bridge/br_device.c:98 __netdev_start_xmit include/linux/netdevice.h:5203 [inline] netdev_start_xmit include/linux/netdevice.h:5212 [inline] xmit_one net/core/dev.c:3826 [inline] dev_hard_start_xmit+0x2d9/0x830 net/core/dev.c:3842 __dev_queue_xmit+0x1b80/0x3f60 net/core/dev.c:4679 __bond_start_xmit include/linux/netdevice.h:-1 [inline] bond_start_xmit+0x138e/0x1c50 drivers/net/bonding/bond_main.c:5599 __netdev_start_xmit include/linux/netdevice.h:5203 [inline] netdev_start_xmit include/linux/netdevice.h:5212 [inline] xmit_one net/core/dev.c:3826 [inline] dev_hard_start_xmit+0x2d9/0x830 net/core/dev.c:3842 sch_direct_xmit+0x2b2/0x600 net/sched/sch_generic.c:343 qdisc_restart net/sched/sch_generic.c:408 [inline] __qdisc_run+0xc0d/0x2180 net/sched/sch_generic.c:416 __dev_xmit_skb net/core/dev.c:4137 [inline] __dev_queue_xmit+0x10e2/0x3f60 net/core/dev.c:4645 dev_queue_xmit include/linux/netdevice.h:3349 [inline] hsr_xmit net/hsr/hsr_forward.c:430 [inline] hsr_forward_do net/hsr/hsr_forward.c:571 [inline] hsr_forward_skb+0x184c/0x2d20 net/hsr/hsr_forward.c:733 hsr_dev_xmit+0x195/0x210 net/hsr/hsr_device.c:235 __netdev_start_xmit include/linux/netdevice.h:5203 [inline] netdev_start_xmit include/linux/netdevice.h:5212 [inline] xmit_one net/core/dev.c:3826 [inline] dev_hard_start_xmit+0x2d9/0x830 net/core/dev.c:3842 __dev_queue_xmit+0x1b80/0x3f60 net/core/dev.c:4679 neigh_output include/net/neighbour.h:539 [inline] ip6_finish_output2+0x1296/0x1750 net/ipv6/ip6_output.c:141 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline] ip6_finish_output+0x421/0x840 net/ipv6/ip6_output.c:226 NF_HOOK+0xa0/0x440 include/linux/netfilter.h:314 mld_sendpack+0x84a/0xdc0 net/ipv6/mcast.c:1868 mld_dad_work+0x44/0x500 net/ipv6/mcast.c:2308 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xac3/0x18e0 kernel/workqueue.c:3319 worker_thread+0x870/0xd50 kernel/workqueue.c:3400 kthread+0x7b7/0x940 kernel/kthread.c:464 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245