INFO: task syz.6.3092:10843 blocked for more than 123 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.3092      state:D stack:0     pid:10843 tgid:10842 ppid:3241   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6054 [inline]
 __schedule+0x1496/0x20b0 kernel/sched/core.c:7867
 __schedule_loop kernel/sched/core.c:7944 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7959
 schedule_timeout+0xc7/0x3b0 kernel/time/timer.c:2596
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common+0x368/0x650 kernel/sched/completion.c:127
 wait_for_completion+0x1c/0x40 kernel/sched/completion.c:148
 rcu_barrier+0x45a/0x580 kernel/rcu/tree.c:4657
 flush_rcu_work+0x71/0x90 kernel/workqueue.c:4349
 kvfree_rcu_barrier+0x22e/0x2e0 kernel/rcu/tree.c:3955
 kmem_cache_destroy+0x32/0x180 mm/slab_common.c:490
 p9_client_destroy+0x44a/0x4a0 net/9p/client.c:1088
 v9fs_session_close+0x52/0x1d0 fs/9p/v9fs.c:506
 v9fs_kill_super+0x60/0x90 fs/9p/vfs_super.c:196
 deactivate_locked_super+0xd2/0x270 fs/super.c:478
 v9fs_mount+0x75a/0x9d0 fs/9p/vfs_super.c:177
 legacy_get_tree+0x106/0x1b0 fs/fs_context.c:662
 vfs_get_tree+0xa1/0x290 fs/super.c:1820
 do_new_mount+0x251/0xb40 fs/namespace.c:3567
 path_mount+0x66a/0xff0 fs/namespace.c:3894
 do_mount fs/namespace.c:3907 [inline]
 __do_sys_mount fs/namespace.c:4117 [inline]
 __se_sys_mount+0x2bf/0x480 fs/namespace.c:4094
 __x64_sys_mount+0xc3/0xf0 fs/namespace.c:4094
 x64_sys_call+0x2021/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f0690b9de99
RSP: 002b:00007f0691b23028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f0690e25fa0 RCX: 00007f0690b9de99
RDX: 0000200000000b80 RSI: 0000200000000000 RDI: 0000000000000000
RBP: 00007f0690c33eaf R08: 00002000000001c0 R09: 0000000000000000
R10: 0000000000010800 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0690e26038 R14: 00007f0690e25fa0 R15: 00007ffcfa8148e8
 </TASK>
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 06b3c97831a10c77d09a2a0513f377ab490362d8
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2ba/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xe45/0xf90 kernel/hung_task.c:423
 kthread+0x2c7/0x360 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 2583 Comm: kworker/u8:57 Not tainted syzkaller #0 06b3c97831a10c77d09a2a0513f377ab490362d8
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
Workqueue: netns cleanup_net
RIP: 0010:__kfree_skb+0x0/0x210 net/core/skbuff.c:1198
Code: 80 e1 07 38 c1 0f 8c 70 ff ff ff 4c 89 f7 e8 17 82 66 fd e9 63 ff ff ff 66 90 b8 e1 3a aa c7 90 90 90 90 90 90 90 90 90 90 90 <f3> 0f 1e fa 55 48 89 e5 41 57 41 56 41 54 53 48 89 fb 49 bc 00 00
RSP: 0018:ffffc90000230158 EFLAGS: 00000246
RAX: ffffffff8479974d RBX: ffff8881ba905000 RCX: ffff888142121300
RDX: 0000000000000100 RSI: 0000000000000001 RDI: ffff8881ba905000
RBP: ffffc90000230180 R08: ffff8881ba9050f7 R09: 1ffff11037520a1e
R10: dffffc0000000000 R11: ffffed1037520a1f R12: dffffc0000000000
R13: ffff8881f6f00000 R14: ffffffff836a9060 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005587fae971f0 CR3: 00000001072b2000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000100404 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 dummy_xmit+0x100/0x170 drivers/net/dummy.c:64
 __netdev_start_xmit include/linux/netdevice.h:5008 [inline]
 netdev_start_xmit include/linux/netdevice.h:5017 [inline]
 xmit_one net/core/dev.c:3693 [inline]
 dev_hard_start_xmit+0x230/0x730 net/core/dev.c:3709
 __dev_queue_xmit+0x1969/0x3780 net/core/dev.c:4549
 dev_queue_xmit include/linux/netdevice.h:3141 [inline]
 br_dev_queue_push_xmit+0x571/0x710 net/bridge/br_forward.c:53
 NF_HOOK include/linux/netfilter.h:317 [inline]
 br_forward_finish net/bridge/br_forward.c:66 [inline]
 NF_HOOK include/linux/netfilter.h:317 [inline]
 __br_forward+0x24f/0x390 net/bridge/br_forward.c:115
 deliver_clone net/bridge/br_forward.c:131 [inline]
 maybe_deliver net/bridge/br_forward.c:191 [inline]
 br_flood+0x500/0x720 net/bridge/br_forward.c:237
 br_handle_frame_finish+0x1157/0x1620 net/bridge/br_input.c:215
 nf_hook_bridge_pre net/bridge/br_input.c:301 [inline]
 br_handle_frame+0x5a5/0xba0 net/bridge/br_input.c:424
 __netif_receive_skb_core+0xfc1/0x3a70 net/core/dev.c:5695
 __netif_receive_skb_one_core net/core/dev.c:5799 [inline]
 __netif_receive_skb net/core/dev.c:5914 [inline]
 process_backlog+0x40b/0xaf0 net/core/dev.c:6250
 __napi_poll+0xcd/0x600 net/core/dev.c:6901
 napi_poll net/core/dev.c:6970 [inline]
 net_rx_action+0x5dc/0xd70 net/core/dev.c:7092
 handle_softirqs+0x1aa/0x620 kernel/softirq.c:621
 __do_softirq+0xf/0x16 kernel/softirq.c:659
 do_softirq+0xb8/0x110 kernel/softirq.c:503
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x74/0x80 kernel/softirq.c:430
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:167 [inline]
 _raw_spin_unlock_bh+0x54/0x60 kernel/locking/spinlock.c:210
 spin_unlock_bh include/linux/spinlock.h:396 [inline]
 addrconf_ifdown+0x60d/0x1970 net/ipv6/addrconf.c:3950
 addrconf_notify+0x17a/0xeb0 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x106/0x2b0 kernel/notifier.c:93
 raw_notifier_call_chain+0x31/0x40 kernel/notifier.c:461
 call_netdevice_notifiers_info net/core/dev.c:2074 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2112 [inline]
 call_netdevice_notifiers net/core/dev.c:2126 [inline]
 unregister_netdevice_many_notify+0xde1/0x1be0 net/core/dev.c:11533
 unregister_netdevice_many+0x1d/0x30 net/core/dev.c:11595
 cleanup_net+0x640/0xc90 net/core/net_namespace.c:637
 process_one_work kernel/workqueue.c:3273 [inline]
 process_scheduled_works+0x7f7/0x1060 kernel/workqueue.c:3354
 worker_thread+0xc99/0x13f0 kernel/workqueue.c:3435
 kthread+0x2c7/0x360 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
net_ratelimit: 97700 callbacks suppressed
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:1a:37:e5:1d:4e:38, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
net_ratelimit: 110749 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:1a:37:e5:1d:4e:38, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)