INFO: task kworker/0:1H:5209 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:26504 pid:5209 tgid:5209 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: kblockd blk_mq_requeue_work
Call Trace:
context_switch kernel/sched/core.c:5298 [inline]
__schedule+0x15dd/0x52d0 kernel/sched/core.c:6911
__schedule_loop kernel/sched/core.c:6993 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7008
schedule_timeout+0x158/0x2c0 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+0x857/0x1100 drivers/block/nbd.c:1207
blk_mq_dispatch_rq_list+0xa70/0x1910 block/blk-mq.c:2148
__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+0xdcc/0x1600 block/blk-mq-sched.c:307
blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2386
blk_mq_run_hw_queues+0x26c/0x3f0 block/blk-mq.c:2435
blk_mq_requeue_work+0x71c/0x780 block/blk-mq.c:1602
process_one_work kernel/workqueue.c:3276 [inline]
process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e75e5a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
#0: ffffffff8e75e5a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
#0: ffffffff8e75e5a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:6/142:
#0: ffff888031c31948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
#0: ffff888031c31948 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0 kernel/workqueue.c:3359
#1: ffffc90002f87c40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3252 [inline]
#1: ffffc90002f87c40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0 kernel/workqueue.c:3359
#2: ffffffff8fbd0ec8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
#2: ffffffff8fbd0ec8 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x11e/0x14c0 net/ipv6/addrconf.c:4198
4 locks held by kworker/0:1H/5209:
#0: ffff88801e2cb548 ((wq_completion)kblockd){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
#0: ffff88801e2cb548 ((wq_completion)kblockd){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0 kernel/workqueue.c:3359
#1: ffffc90003407c40 ((work_completion)(&(&q->requeue_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3252 [inline]
#1: ffffc90003407c40 ((work_completion)(&(&q->requeue_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0 kernel/workqueue.c:3359
#2: ffff8880259bde18 (set->srcu){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:187 [inline]
#2: ffff8880259bde18 (set->srcu){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:294 [inline]
#2: ffff8880259bde18 (set->srcu){.+.+}-{0:0}, at: blk_mq_run_hw_queue+0x31f/0x4f0 block/blk-mq.c:2386
#3: ffff888026488780 (&cmd->lock){+.+.}-{4:4}, at: nbd_queue_rq+0xc6/0x1100 drivers/block/nbd.c:1199
2 locks held by getty/5579:
#0: ffff888036d650a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0 drivers/tty/n_tty.c:2211
1 lock held by udevd/5811:
#0: ffff888026433358 (&disk->open_mutex){+.+.}-{4:4}, at: bdev_open+0xe0/0xd30 block/bdev.c:961
2 locks held by syz.3.4939/23965:
#0: ffffffff8fbd0ec8 (rtnl_mutex){+.+.}-{4:4}, at: ppp_release+0x87/0x1f0 drivers/net/ppp/ppp_generic.c:413
#1: ffffffff8e7648b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: exp_funnel_lock kernel/rcu/tree_exp.h:311 [inline]
#1: ffffffff8e7648b8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770 kernel/rcu/tree_exp.h:961
1 lock held by syz.1.4940/23969:
#0: ffffffff8fbd0ec8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
#0: ffffffff8fbd0ec8 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x722/0xbe0 net/core/rtnetlink.c:7000
=============================================
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 03/18/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:161 [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:346 [inline]
watchdog+0xfd9/0x1030 kernel/hung_task.c:515
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6444 Comm: kworker/u8:9 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: ipv6_addrconf addrconf_dad_work
RIP: 0010:hlock_class kernel/locking/lockdep.c:246 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4879 [inline]
RIP: 0010:__lock_acquire+0x526/0x2cf0 kernel/locking/lockdep.c:5187
Code: 83 c3 28 41 89 c4 49 39 cf 0f 8d c7 00 00 00 49 83 ff 31 0f 83 83 00 00 00 8b 03 25 ff 1f 00 00 48 0f a3 05 cc f4 82 12 73 10 <48> 69 c0 c8 00 00 00 48 8d 88 10 94 c5 93 eb 32 83 3d 93 84 86 18
RSP: 0018:ffffc90003576f18 EFLAGS: 00000007
RAX: 0000000000000082 RBX: ffff88807f9e8bc8 RCX: 0000000000000003
RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88807f9e8bd0 R08: ffffffff81768a55 R09: ffffffff8e75e5a0
R10: ffffc900035771f8 R11: ffffffff81b0dc10 R12: 00000000ffffff05
R13: ffff88807f9e8bd0 R14: ffff88807f9e8000 R15: 0000000000000002
FS: 0000000000000000(0000) GS:ffff888125554000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb0667e92f8 CR3: 000000000e54c000 CR4: 00000000003526f0
Call Trace:
lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868
rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
rcu_read_lock include/linux/rcupdate.h:850 [inline]
class_rcu_constructor include/linux/rcupdate.h:1193 [inline]
unwind_next_frame+0xc2/0x23c0 arch/x86/kernel/unwind_orc.c:495
arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2685 [inline]
slab_free mm/slub.c:6165 [inline]
kmem_cache_free+0x187/0x630 mm/slub.c:6295
netlink_broadcast_filtered+0xee4/0x1020 net/netlink/af_netlink.c:1535
nlmsg_multicast_filtered include/net/netlink.h:1165 [inline]
nlmsg_multicast include/net/netlink.h:1184 [inline]
nlmsg_notify+0xf0/0x1a0 net/netlink/af_netlink.c:2593
inet6_ifa_notify net/ipv6/addrconf.c:5625 [inline]
__ipv6_ifa_notify+0x21e/0xc60 net/ipv6/addrconf.c:6274
ipv6_ifa_notify net/ipv6/addrconf.c:6326 [inline]
addrconf_dad_completed+0x19b/0xe60 net/ipv6/addrconf.c:4324
addrconf_dad_work+0xc5e/0x14c0 net/ipv6/addrconf.c:-1
process_one_work kernel/workqueue.c:3276 [inline]
process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359
worker_thread+0xa53/0xfc0 kernel/workqueue.c:3440
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245