INFO: task kworker/u4:0:9 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:0    state:D stack:24384 pid:    9 ppid:     2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xc71/0x2390 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
 hfsplus_cat_write_inode+0x1e3/0x820 fs/hfsplus/inode.c:588
 write_inode fs/fs-writeback.c:1505 [inline]
 __writeback_single_inode+0x6c3/0xda0 fs/fs-writeback.c:1715
 writeback_sb_inodes+0x9fe/0x1610 fs/fs-writeback.c:1940
 __writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:2011
 wb_writeback+0x455/0xb90 fs/fs-writeback.c:2116
 wb_check_background_flush fs/fs-writeback.c:2182 [inline]
 wb_do_writeback fs/fs-writeback.c:2270 [inline]
 wb_workfn+0xb47/0xe60 fs/fs-writeback.c:2298
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Showing all locks held in the system:
4 locks held by kworker/u4:0/9:
 #0: ffff888142b80938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc90000ce7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffff88801a3cc0e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff888019db40b0 (&tree->tree_lock){+.+.}-{3:3}, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
3 locks held by kworker/1:0/21:
 #0: ffff888016870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc90000db7d00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffff888060e93240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x271/0x3240 drivers/net/netdevsim/fib.c:1480
1 lock held by khungtaskd/27:
 #0: ffffffff8c11c760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
4 locks held by kworker/u4:1/144:
 #0: ffff888142b80938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc9000171fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffff888024efa0e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff8880740000b0 (&tree->tree_lock){+.+.}-{3:3}, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
3 locks held by kworker/u4:2/154:
4 locks held by kworker/u4:3/398:
 #0: ffff888142b80938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc9000325fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffff8880266380e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff888028e2e0b0 (&tree->tree_lock){+.+.}-{3:3}, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
4 locks held by kworker/u4:4/1240:
 #0: ffff888142b80938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc900051d7d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffff88807bb2a0e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff888077d180b0 (&tree->tree_lock){+.+.}-{3:3}, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
2 locks held by getty/3947:
 #0: ffff88814ca60098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900025e62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
3 locks held by kworker/1:5/4268:
 #0: ffff88802b6a8d38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc90002f3fd00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffffffff8d238988 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xc4/0x1520 net/ipv6/addrconf.c:4110
6 locks held by syz.0.17/4482:
6 locks held by syz.1.18/4544:
4 locks held by kworker/u4:5/4557:
 #0: ffff888142b80938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc9000421fd00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffff88807be1e0e0 (&type->s_umount_key#54){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: ffff88807e08a0b0 (&tree->tree_lock){+.+.}-{3:3}, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
6 locks held by syz.2.19/4568:
6 locks held by syz.3.20/4596:
4 locks held by kworker/u4:7/4613:
 #0: 
ffff888142b80938
 (
(wq_completion)writeback
){+.+.}-{0:0}
, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: 
ffffc9000445fd00
 (
(work_completion)(&(&wb->dwork)->work)
){+.+.}-{0:0}
, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: 
ffff8880798120e0
 (
&type->s_umount_key
#54
){.+.+}-{3:3}
, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: 
ffff8880598480b0
 (
&tree->tree_lock
){+.+.}-{3:3}
, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
3 locks held by kworker/u4:8/4625:
 #0: 
ffff888016879138
 (
(wq_completion)events_unbound
){+.+.}-{0:0}
, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: 
ffffc9000446fd00
 (
(linkwatch_work).work
){+.+.}-{0:0}
, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffffffff8d238988 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:251
6 locks held by syz.4.21/4626:
4 locks held by kworker/u4:9/4643:
 #0: ffff888142b80938 ((wq_completion)writeback
){+.+.}-{0:0}
, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: 
ffffc9000457fd00
 (
(work_completion)(&(&wb->dwork)->work)
){+.+.}-{0:0}
, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: 
ffff88802291e0e0
 (
&type->s_umount_key
#54
){.+.+}-{3:3}
, at: trylock_super+0x1c/0xf0 fs/super.c:418
 #3: 
ffff888021d760b0
 (
&tree->tree_lock
){+.+.}-{3:3}
, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
6 locks held by syz.5.22/4655:
9 locks held by syz.6.23/4690:
2 locks held by syz-executor/4692:
 #0: 
ffffffff8d238988
 (
rtnl_mutex
){+.+.}-{3:3}
, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
, at: rtnetlink_rcv_msg+0x7a5/0xe90 net/core/rtnetlink.c:5681
 #1: 
ffffffff8c1211e8
 (
rcu_state.exp_mutex
){+.+.}-{3:3}
, at: exp_funnel_lock kernel/rcu/tree_exp.h:290 [inline]
, at: synchronize_rcu_expedited+0x347/0x6b0 kernel/rcu/tree_exp.h:845

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4626 Comm: syz.4.21 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:rdtsc_ordered arch/x86/include/asm/msr.h:224 [inline]
RIP: 0010:delay_tsc+0x6d/0xc0 arch/x86/lib/delay.c:72
Code: 00 00 e8 86 ff 50 fd 65 8b 05 17 fd 01 7c 85 c0 74 1c f3 90 bf 01 00 00 00 e8 df fd 50 fd e8 1a 0b a9 05 39 c5 75 0e 0f 01 f9 <66> 90 eb bd e8 aa 07 00 fd eb dd 4c 29 fb e8 00 0b a9 05 89 c5 0f
RSP: 0018:ffffc900044bf0d0 EFLAGS: 00000046
RAX: 00000000a0e9a568 RBX: 0000000000000899 RCX: 0000000000000001
RDX: 00000000000000ad RSI: ffffffff8a59e560 RDI: ffffffff8a59e520
RBP: 0000000000000001 R08: 0000000000000004 R09: 0000000000000003
R10: fffff52000897e10 R11: 1ffff92000897e10 R12: 000000000000270c
R13: ffffffff963ebaa8 R14: 000000ada0e99d54 R15: 000000000000075b
FS:  00005555910df500(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0a637d15c0 CR3: 0000000079ae3000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 wait_for_xmitr+0xb9/0x260 drivers/tty/serial/8250/8250_port.c:2077
 serial8250_console_putchar+0x1a/0x50 drivers/tty/serial/8250/8250_port.c:3309
 uart_console_write+0xaa/0x100 drivers/tty/serial/serial_core.c:1981
 serial8250_console_write+0xbb5/0xf80 drivers/tty/serial/8250/8250_port.c:3386
 call_console_drivers kernel/printk/printk.c:-1 [inline]
 console_unlock+0xc86/0x1200 kernel/printk/printk.c:2744
 vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274
 _printk+0xcc/0x110 kernel/printk/printk.c:2299
 hfsplus_bnode_read_u16 fs/hfsplus/bnode.c:62 [inline]
 hfsplus_bnode_dump+0x30b/0x430 fs/hfsplus/bnode.c:369
 hfsplus_brec_remove+0x476/0x540 fs/hfsplus/brec.c:229
 __hfsplus_delete_attr+0x1d1/0x360 fs/hfsplus/attributes.c:299
 hfsplus_delete_all_attrs+0x240/0x3a0 fs/hfsplus/attributes.c:378
 hfsplus_delete_cat+0x94a/0xd20 fs/hfsplus/catalog.c:425
 hfsplus_unlink+0x33c/0x760 fs/hfsplus/dir.c:385
 vfs_unlink+0x385/0x600 fs/namei.c:4288
 do_unlinkat+0x382/0x6f0 fs/namei.c:4356
 __do_sys_unlinkat fs/namei.c:4399 [inline]
 __se_sys_unlinkat fs/namei.c:4392 [inline]
 __x64_sys_unlinkat+0xd1/0xe0 fs/namei.c:4392
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f28f0d42749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe3629bcd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 00007f28f0f98fa0 RCX: 00007f28f0d42749
RDX: 0000000000000000 RSI: 0000200000000380 RDI: ffffffffffffff9c
RBP: 00007f28f0dc6f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f28f0f98fa0 R14: 00007f28f0f98fa0 R15: 0000000000000003
 </TASK>