INFO: task kworker/0:1H:1670 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:1H    state:D stack:26920 pid:1670  tgid:1670  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: kblockd blk_mq_run_work_fn
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5510 [inline]
 __schedule+0x17d9/0x56c0 kernel/sched/core.c:7234
 __schedule_loop kernel/sched/core.c:7311 [inline]
 schedule+0x164/0x2b0 kernel/sched/core.c:7326
 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99
 wait_for_reconnect drivers/block/nbd.c:1107 [inline]
 nbd_handle_cmd drivers/block/nbd.c:1149 [inline]
 nbd_queue_rq+0x889/0x1150 drivers/block/nbd.c:1207
 blk_mq_dispatch_rq_list+0x499/0x1990 block/blk-mq.c:2117
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
 blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
 __blk_mq_sched_dispatch_requests+0xd36/0x1580 block/blk-mq-sched.c:307
 blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
 blk_mq_run_work_fn+0x16c/0x300 block/blk-mq.c:2532
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
5 locks held by kworker/u8:2/36:
 #0: ffff8880b873b160 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2d/0x160 kernel/sched/core.c:667
 #1: ffff8880b8724440 (psi_seq){-.-.}-{0:0}, at: psi_task_switch+0x57/0x7d0 kernel/sched/psi.c:933
 #2: ffff8880b87281d8 (hrtimer_bases.lock){-.-.}-{2:2}, at: class_raw_spinlock_constructor include/linux/spinlock.h:536 [inline]
 #2: ffff8880b87281d8 (hrtimer_bases.lock){-.-.}-{2:2}, at: __hrtimer_rearm_deferred+0x99/0x420 kernel/time/hrtimer.c:2153
 #3: ffffffff9a7cc748 (&____s->seqcount#2){----}-{0:0}, at: ktime_get+0x45/0x220 kernel/time/timekeeping.c:971
 #4: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #4: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #4: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1183 [inline]
 #4: ffffffff8eb59c60 (rcu_read_lock){....}-{1:3}, at: unwind_next_frame+0x8f/0x2550 arch/x86/kernel/unwind_orc.c:495
4 locks held by kworker/0:1H/1670:
 #0: ffff88801eaacd40 ((wq_completion)kblockd){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #0: ffff88801eaacd40 ((wq_completion)kblockd){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
 #1: ffffc90006757c40 ((work_completion)(&(&hctx->run_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #1: ffffc90006757c40 ((work_completion)(&(&hctx->run_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
 #2: ffff888027618418 (set->srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:187 [inline]
 #2: ffff888027618418 (set->srcu){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:294 [inline]
 #2: ffff888027618418 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_work_fn+0x144/0x300 block/blk-mq.c:2531
 #3: ffff8880277c0178 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xc1/0x1150 drivers/block/nbd.c:1199
2 locks held by getty/5386:
 #0: ffff88803698f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211
1 lock held by udevd/7051:
 #0: ffff888026ff0350 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xde/0xd70 block/bdev.c:948
3 locks held by kworker/u8:20/10006:
 #0: ffff88801b06c140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #0: ffff88801b06c140 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
 #1: ffffc9001ac5fc40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
 #1: ffffc9001ac5fc40 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
 #2: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:313
1 lock held by syz.4.3706/19809:
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: bpf_xdp_link_release+0x26/0x520 net/core/dev.c:10558
1 lock held by syz.4.3706/19810:
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8a3/0x1bd0 net/core/rtnetlink.c:4158
3 locks held by syz.4.3706/19815:
 #0: ffffffff9057d300 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff9057d300 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
 #0: ffffffff9057d300 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8a3/0x1bd0 net/core/rtnetlink.c:4158
 #2: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline]
 #2: ffffffff8eb5ff68 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770 kernel/rcu/tree_exp.h:961
1 lock held by syz.0.3707/19816:
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x767/0xc00 net/core/rtnetlink.c:7082
1 lock held by syz.0.3707/19819:
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x767/0xc00 net/core/rtnetlink.c:7082
2 locks held by syz.2.3708/19818:
 #0: ffffffff9009e428 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: nl80211_pre_doit+0x5e/0x890 net/wireless/nl80211.c:19299
1 lock held by syz.2.3708/19824:
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_dellink+0x41b/0x810 net/core/rtnetlink.c:3635
1 lock held by syz.3.3709/19822:
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff9002dac0 (rtnl_mutex){+.+.}-{4:4}, at: rtm_new_nexthop+0xff1/0x81f0 net/ipv4/nexthop.c:3326

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:122
 nmi_trigger_cpumask_backtrace+0x17a/0x380 lib/nmi_backtrace.c:65
 trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
 watchdog+0xfd7/0x1030 kernel/hung_task.c:561
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 19810 Comm: syz.4.3706 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:match_held_lock+0x0/0xb0 kernel/locking/lockdep.c:5305
Code: 67 48 0f b9 3a 90 31 db 48 89 d8 5b 41 5e 41 5f c3 cc cc cc cc cc 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <41> 56 53 bb 01 00 00 00 48 39 77 10 74 6a 81 7f 20 00 00 20 00 72
RSP: 0018:ffffc90000a089d8 EFLAGS: 00000087
RAX: 0000000000000005 RBX: ffff88807c568c18 RCX: 0000000000000104
RDX: 0000000000000000 RSI: ffffffff8ea1b7a0 RDI: ffff88807c568c18
RBP: 00000000ffffffff R08: ffff888020ea42b7 R09: 1ffff110041d4856
R10: dffffc0000000000 R11: ffffed10041d4857 R12: 0000000000000046
R13: ffff88807c568000 R14: ffffffff8ea1b7a0 R15: 0000000000000003
FS:  00007fcc348006c0(0000) GS:ffff88812504d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c393f20 CR3: 0000000075092000 CR4: 00000000003526f0
Call Trace:
 <IRQ>
 __lock_is_held kernel/locking/lockdep.c:5601 [inline]
 lock_is_held_type+0x89/0x150 kernel/locking/lockdep.c:5940
 lock_is_held include/linux/lockdep.h:249 [inline]
 select_task_rq_fair+0x3a3/0x4920 kernel/sched/fair.c:9575
 select_task_rq kernel/sched/core.c:3619 [inline]
 try_to_wake_up+0x5c9/0x14d0 kernel/sched/core.c:4393
 kick_pool+0x479/0x640 kernel/workqueue.c:1313
 __queue_work+0xce5/0x10a0 kernel/workqueue.c:2402
 call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
 expire_timers kernel/time/timer.c:1794 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x67e/0x8b0 kernel/time/timer.c:2386
 run_timer_base kernel/time/timer.c:2395 [inline]
 run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
 handle_softirqs+0x225/0x840 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:console_trylock_spinning kernel/printk/printk.c:2039 [inline]
RIP: 0010:vprintk_emit+0x45d/0x560 kernel/printk/printk.c:2478
Code: 0f 84 44 ff ff ff e8 72 6c 21 00 fb eb 44 e8 6a 6c 21 00 e8 85 ed 2b 0a 4d 85 f6 74 94 e8 5b 6c 21 00 fb 48 c7 c7 a0 bf b4 8e <31> f6 ba 01 00 00 00 31 c9 41 b8 01 00 00 00 45 31 c9 53 e8 fb 1b
RSP: 0018:ffffc9000385e7c0 EFLAGS: 00000293
RAX: ffffffff81a5a7a5 RBX: ffffffff81a5a61f RCX: ffff88807c568000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8eb4bfa0
RBP: ffffc9000385e870 R08: ffffffff90579937 R09: 1ffffffff20af326
R10: dffffc0000000000 R11: fffffbfff20af327 R12: 0000000000000000
R13: 0000000000000026 R14: 0000000000000200 R15: 1ffff9200070bcfc
 _printk+0xdd/0x130 kernel/printk/printk.c:2504
 netdev_info+0x11e/0x180 net/core/dev.c:13019
 netif_set_allmulti+0x2d0/0x4d0 net/core/dev.c:9679
 dev_set_allmulti+0x121/0x260 net/core/dev_api.c:315
 nbp_delete_promisc net/bridge/br_if.c:253 [inline]
 del_nbp+0xb4/0x9f0 net/bridge/br_if.c:341
 br_del_if+0x143/0x1e0 net/bridge/br_if.c:732
 do_set_master+0x332/0x720 net/core/rtnetlink.c:3004
 do_setlink+0xe7b/0x4670 net/core/rtnetlink.c:3222
 rtnl_group_changelink net/core/rtnetlink.c:3863 [inline]
 __rtnl_newlink net/core/rtnetlink.c:4031 [inline]
 rtnl_newlink+0x148e/0x1bd0 net/core/rtnetlink.c:4159
 rtnetlink_rcv_msg+0x802/0xc00 net/core/rtnetlink.c:7076
 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
 netlink_unicast+0x7bb/0x940 net/netlink/af_netlink.c:1345
 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
 sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
 __sock_sendmsg net/socket.c:790 [inline]
 ____sys_sendmsg+0x54e/0x850 net/socket.c:2684
 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2738
 __sys_sendmsg net/socket.c:2770 [inline]
 __do_sys_sendmsg net/socket.c:2775 [inline]
 __se_sys_sendmsg net/socket.c:2773 [inline]
 __x64_sys_sendmsg+0x1b1/0x290 net/socket.c:2773
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcc3399e019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcc34800028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fcc33c25fa0 RCX: 00007fcc3399e019
RDX: 0000000004000880 RSI: 0000200000000140 RDI: 0000000000000003
RBP: 00007fcc33a3500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcc33c26038 R14: 00007fcc33c25fa0 R15: 00007ffecb9369a8
 </TASK>