INFO: task kworker/u8:1:13 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:1    state:D stack:20792 pid:13    tgid:13    ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0x1472/0x4fe0 kernel/sched/core.c:6867
 __schedule_loop kernel/sched/core.c:6949 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7245
 rt_mutex_slowlock_block+0x508/0x680 kernel/locking/rtmutex.c:1647
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
 __rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1760 [inline]
 rt_mutex_slowlock+0x2dc/0x710 kernel/locking/rtmutex.c:1800
 __rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
 __mutex_lock_common kernel/locking/rtmutex_api.c:534 [inline]
 mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:552
 jfs_commit_inode+0x1ca/0x530 fs/jfs/inode.c:108
 jfs_write_inode+0x145/0x220 fs/jfs/inode.c:138
 write_inode fs/fs-writeback.c:1582 [inline]
 __writeback_single_inode+0x7e4/0x1230 fs/fs-writeback.c:1802
 writeback_sb_inodes+0x92e/0x1910 fs/fs-writeback.c:2030
 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2107
 wb_writeback+0x459/0xad0 fs/fs-writeback.c:2218
 wb_check_old_data_flush fs/fs-writeback.c:2322 [inline]
 wb_do_writeback fs/fs-writeback.c:2375 [inline]
 wb_workfn+0xaf3/0xf00 fs/fs-writeback.c:2403
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340
 worker_thread+0xda6/0x1360 kernel/workqueue.c:3421
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u8:1/13:
 #0: ffff888140463938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff888140463938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc90000127bc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc90000127bc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
 #2: ffff88803035e0d0 (&type->s_umount_key#77){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563
 #3: ffff88804b058ba8 (&jfs_ip->commit_mutex){+.+.}-{4:4}, at: jfs_commit_inode+0x1ca/0x530 fs/jfs/inode.c:108
1 lock held by khungtaskd/38:
 #0: ffffffff8dbc77c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8dbc77c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8dbc77c0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:3/58:
 #0: ffff88813fe69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff88813fe69938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc9000124fbc0 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc9000124fbc0 ((linkwatch_work).work){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
 #2: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: linkwatch_event+0xe/0x60 net/core/link_watch.c:303
3 locks held by kworker/u8:7/1819:
 #0: ffff888030d1b138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff888030d1b138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc900057b7bc0 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc900057b7bc0 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
 #2: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #2: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x124/0x1680 net/ipv6/addrconf.c:4194
4 locks held by kworker/u8:11/3582:
 #0: ffff88801aad4938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff88801aad4938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc9000df27bc0 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc9000df27bc0 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
 #2: ffffffff8ef2caa0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xfe/0x7b0 net/core/net_namespace.c:670
 #3: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: default_device_exit_batch+0xe5/0xa00 net/core/dev.c:13037
2 locks held by dhcpcd/5462:
 #0: ffffffff8efa9c60 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1218
 #1: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: nl80211_pre_doit+0x5f/0x930 net/wireless/nl80211.c:17922
2 locks held by getty/5555:
 #0: ffff888035a950a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900042132e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13c0 drivers/tty/n_tty.c:2211
4 locks held by kworker/u9:6/5813:
3 locks held by kworker/u9:0/15665:
 #0: ffff888036873938 ((wq_completion)hci9){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
 #0: ffff888036873938 ((wq_completion)hci9){+.+.}-{0:0}, at: process_scheduled_works+0x9d4/0x17a0 kernel/workqueue.c:3340
 #1: ffffc9000aa27bc0 ((work_completion)(&hdev->power_on)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
 #1: ffffc9000aa27bc0 ((work_completion)(&hdev->power_on)){+.+.}-{0:0}, at: process_scheduled_works+0xa0f/0x17a0 kernel/workqueue.c:3340
 #2: ffff888027670f80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_open net/bluetooth/hci_core.c:428 [inline]
 #2: ffff888027670f80 (&hdev->req_lock){+.+.}-{4:4}, at: hci_power_on+0x1ac/0x710 net/bluetooth/hci_core.c:959
4 locks held by syz.0.1514/18841:
1 lock held by syz-executor/21189:
 #0: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x404/0x1ad0 net/ipv4/devinet.c:978
1 lock held by syz-executor/21314:
 #0: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x404/0x1ad0 net/ipv4/devinet.c:978
1 lock held by syz-executor/21824:
 #0: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: inet6_rtm_newaddr+0x65f/0xe30 net/ipv6/addrconf.c:5027
7 locks held by syz-executor/22038:
 #0: ffff888035fcc480 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2683 [inline]
 #0: ffff888035fcc480 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22d/0xba0 fs/read_write.c:682
 #1: ffff88805b931878 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1df/0x540 fs/kernfs/file.c:343
 #2: ffff888143b7f008 (kn->active#53){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #2: ffff888143b7f008 (kn->active#53){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x232/0x540 fs/kernfs/file.c:344
 #3: ffffffff8e7aa818 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: new_device_store+0x13c/0x710 drivers/net/netdevsim/bus.c:184
 #4: ffff8880636ab0d8 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #4: ffff8880636ab0d8 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1008
 #5: ffff88803175c300 (&devlink->lock_key#33){+.+.}-{4:4}, at: nsim_drv_probe+0xc9/0xc30 drivers/net/netdevsim/dev.c:1637
 #6: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: nsim_init_netdevsim drivers/net/netdevsim/netdev.c:1049 [inline]
 #6: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: nsim_create+0x839/0x1120 drivers/net/netdevsim/netdev.c:1143
2 locks held by syz-executor/22796:
 #0: ffffffff8e6988a8 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e6988a8 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8e6988a8 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8a1/0x1be0 net/core/rtnetlink.c:4071
1 lock held by syz-executor/22993:
 #0: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x404/0x1ad0 net/ipv4/devinet.c:978
1 lock held by syz-executor/23002:
 #0: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x404/0x1ad0 net/ipv4/devinet.c:978
1 lock held by syz-executor/23010:
 #0: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8ef3b3b8 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x404/0x1ad0 net/ipv4/devinet.c:978
1 lock held by syz-executor/23021:
 #0: ffff88805a326860 (&data->read_wait){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:44 [inline]
 #0: ffff88805a326860 (&data->read_wait){+.+.}-{3:3}, at: finish_wait+0xbe/0x1e0 kernel/sched/wait.c:394

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
 <TASK>
 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+0xf90/0xfe0 kernel/hung_task.c:515
 kthread+0x726/0x8b0 kernel/kthread.c:463
 ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 5157 Comm: klogd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:hlock_class kernel/locking/lockdep.c:234 [inline]
RIP: 0010:check_wait_context kernel/locking/lockdep.c:4854 [inline]
RIP: 0010:__lock_acquire+0x35e/0x2cf0 kernel/locking/lockdep.c:5187
Code: 09 d4 41 09 cc 41 09 dc 45 89 64 c7 20 41 89 7c c7 24 4c 89 7c 24 20 4d 8d 2c c7 41 81 e4 ff 1f 00 00 4c 0f a3 25 42 4d 8e 11 <73> 15 49 69 c4 c8 00 00 00 48 8d 80 90 33 ce 92 4c 8b 74 24 08 eb
RSP: 0018:ffffc9000414f3d8 EFLAGS: 00000007
RAX: 0000000000000000 RBX: 0000000000040000 RCX: 0000000000000100
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff821cb9b0 R09: ffff8880b8941be8
R10: ffff88806306e780 R11: ffffffff81ae5ef0 R12: 0000000000000100
R13: ffff8880376929d0 R14: ffff888037691e40 R15: ffff8880376929d0
FS:  00007f42b899dc80(0000) GS:ffff8881266c9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d9cc7c76e0 CR3: 0000000037012000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 lock_acquire+0x106/0x330 kernel/locking/lockdep.c:5868
 rt_spin_lock+0x83/0x400 kernel/locking/spinlock_rt.c:56
 spin_lock include/linux/spinlock_rt.h:44 [inline]
 ___slab_alloc+0x130/0x13d0 mm/slub.c:4521
 __slab_alloc+0xc5/0x1f0 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 __do_kmalloc_node mm/slub.c:5656 [inline]
 __kmalloc_node_track_caller_noprof+0x2b6/0x7f0 mm/slub.c:5768
 kmalloc_reserve+0x136/0x290 net/core/skbuff.c:608
 __alloc_skb+0x204/0x390 net/core/skbuff.c:690
 alloc_skb include/linux/skbuff.h:1383 [inline]
 alloc_skb_with_frags+0xca/0x890 net/core/skbuff.c:6715
 sock_alloc_send_pskb+0x884/0x9a0 net/core/sock.c:2995
 unix_dgram_sendmsg+0x460/0x18e0 net/unix/af_unix.c:2130
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 __sys_sendto+0x72a/0x7d0 net/socket.c:2206
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xde/0x100 net/socket.c:2209
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f42b8aed407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fff6e0db870 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f42b899dc80 RCX: 00007f42b8aed407
RDX: 000000000000004f RSI: 00007fff6e0db9b0 RDI: 0000000000000003
RBP: 00007fff6e0dbde0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000004000 R11: 0000000000000202 R12: 00007fff6e0dbdf8
R13: 00007fff6e0db9b0 R14: 0000000000000034 R15: 00007fff6e0db9b0
 </TASK>