INFO: task syz.1.4241:12988 blocked for more than 122 seconds. Not tainted 6.12.38-syzkaller-gb632dc2e1d79 #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.1.4241 state:D stack:0 pid:12988 tgid:12988 ppid:10501 flags:0x00004006 Call Trace: context_switch kernel/sched/core.c:5945 [inline] __schedule+0x1322/0x1df0 kernel/sched/core.c:7791 __schedule_loop kernel/sched/core.c:7872 [inline] schedule+0xc6/0x240 kernel/sched/core.c:7887 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:7944 __mutex_lock_common kernel/locking/mutex.c:707 [inline] __mutex_lock+0x81e/0x1b50 kernel/locking/mutex.c:803 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1134 mutex_lock+0x102/0x1c0 kernel/locking/mutex.c:285 rcu_barrier+0x4d/0x530 kernel/rcu/tree.c:4589 netdev_run_todo+0x10e/0xcb0 net/core/dev.c:10868 rtnl_unlock+0x12/0x20 net/core/rtnetlink.c:152 tun_detach drivers/net/tun.c:704 [inline] tun_chr_close+0xc5/0x150 drivers/net/tun.c:3517 __fput+0x1fe/0xa00 fs/file_table.c:429 ____fput+0x20/0x30 fs/file_table.c:457 task_work_run+0x1e0/0x250 kernel/task_work.c:240 exit_task_work include/linux/task_work.h:43 [inline] do_exit+0x9bc/0x2630 kernel/exit.c:953 do_group_exit+0x22a/0x300 kernel/exit.c:1095 get_signal+0x139d/0x14f0 kernel/signal.c:2933 arch_do_signal_or_restart+0x96/0x720 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x58/0xb0 kernel/entry/common.c:218 do_syscall_64+0x64/0xf0 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f47f71c14a5 RSP: 002b:00007f47f8018f80 EFLAGS: 00000293 ORIG_RAX: 00000000000000e6 RAX: fffffffffffffdfc RBX: 00007f47f73b5fa0 RCX: 00007f47f71c14a5 RDX: 00007f47f8018fc0 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007f47f7211e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 00007f47f73b6038 R14: 00007f47f73b5fa0 R15: 00007fffa7a38a38 NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Not tainted 6.12.38-syzkaller-gb632dc2e1d79 #0 9921eaa9ec7b66c9f160f95d92f0c8099666722b Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Call Trace: __dump_stack+0x21/0x30 lib/dump_stack.c:94 dump_stack_lvl+0x10c/0x190 lib/dump_stack.c:120 dump_stack+0x19/0x20 lib/dump_stack.c:129 nmi_cpu_backtrace+0x2bf/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+0xd8f/0xed0 kernel/hung_task.c:423 kthread+0x2ca/0x370 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 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 64 Comm: kworker/1:2 Not tainted 6.12.38-syzkaller-gb632dc2e1d79 #0 9921eaa9ec7b66c9f160f95d92f0c8099666722b Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Workqueue: events_power_efficient neigh_periodic_work RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline] RIP: 0010:write_comp_data kernel/kcov.c:246 [inline] RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x33/0x90 kernel/kcov.c:314 Code: 8b 45 08 65 48 8b 14 25 00 eb 04 00 65 8b 0d 7c 09 7f 7e 81 e1 00 01 ff 00 74 11 81 f9 00 01 00 00 75 5b 83 ba ec 0b 00 00 00 <74> 52 8b 8a c8 0b 00 00 83 f9 03 75 47 48 8b 8a d0 0b 00 00 44 8b RSP: 0018:ffffc90000230478 EFLAGS: 00000246 RAX: ffffffff84e11462 RBX: ffff88814e2f8140 RCX: 0000000000000100 RDX: ffff88810d2ccc00 RSI: 00000000000000ff RDI: 00000000000000ff RBP: ffffc90000230478 R08: ffff88814e2f817f R09: 0000000000000000 R10: ffff88814e2f8168 R11: ffffed1029c5f030 R12: 0000000000000002 R13: ffff888137eb1418 R14: 00000000000000ff R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5cd10feff8 CR3: 000000011dd24000 CR4: 00000000003526b0 Call Trace: ipv6_addr_is_multicast include/net/ipv6.h:812 [inline] ip6_rcv_core+0x922/0x1300 net/ipv6/ip6_input.c:235 ipv6_rcv+0xce/0x220 net/ipv6/ip6_input.c:306 __netif_receive_skb_one_core net/core/dev.c:5757 [inline] __netif_receive_skb net/core/dev.c:5870 [inline] netif_receive_skb_internal net/core/dev.c:5956 [inline] netif_receive_skb+0x147/0x7b0 net/core/dev.c:6015 br_netif_receive_skb net/bridge/br_input.c:30 [inline] NF_HOOK include/linux/netfilter.h:317 [inline] br_pass_frame_up+0x126/0x1c0 net/bridge/br_input.c:70 br_handle_frame_finish+0x12d9/0x1720 net/bridge/br_input.c:221 nf_hook_bridge_pre net/bridge/br_input.c:301 [inline] br_handle_frame+0x5a6/0xba0 net/bridge/br_input.c:424 __netif_receive_skb_core+0xf4b/0x3940 net/core/dev.c:5651 __netif_receive_skb_one_core net/core/dev.c:5755 [inline] __netif_receive_skb net/core/dev.c:5870 [inline] process_backlog+0x3e5/0xae0 net/core/dev.c:6206 __napi_poll+0xd0/0x610 net/core/dev.c:6857 napi_poll net/core/dev.c:6926 [inline] net_rx_action+0x584/0xce0 net/core/dev.c:7048 handle_softirqs+0x1ab/0x630 kernel/softirq.c:621 __do_softirq+0xf/0x16 kernel/softirq.c:659 do_softirq+0xa6/0x100 kernel/softirq.c:503 __local_bh_enable_ip+0x74/0x80 kernel/softirq.c:430 __raw_write_unlock_bh include/linux/rwlock_api_smp.h:281 [inline] _raw_write_unlock_bh+0x33/0x70 kernel/locking/spinlock.c:366 neigh_periodic_work+0xa73/0xbc0 net/core/neighbour.c:1019 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0x7d2/0x1020 kernel/workqueue.c:3319 worker_thread+0xc58/0x1250 kernel/workqueue.c:3400 kthread+0x2ca/0x370 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 net_ratelimit: 128033 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 bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, 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:9a:20:c1:bd:41:d3, 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 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 veth0_to_bridge with own address as source address (addr:9a:20:c1:bd:41:d3, vlan:0) net_ratelimit: 133629 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 bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, 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:9a:20:c1:bd:41:d3, 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: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:9a:20:c1:bd:41:d3, vlan:0)