[v6.1] INFO: task hung in hfsplus_find_init

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 50cbba13faa2 Linux 6.1.159
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12fd9b92580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6a5cbd268406bf43
dashboard link: https://syzkaller.appspot.com/bug?extid=b797a2c255e4b0845444
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/50ceb00b1b39/disk-50cbba13.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ebb8883b9a29/vmlinux-50cbba13.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7edc2a795f03/bzImage-50cbba13.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b797a2...@syzkaller.appspotmail.com

INFO: task kworker/u4:17:5495 blocked for more than 146 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:17 state:D stack:25128 pid:5495 ppid:2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:4)
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
schedule+0xb9/0x180 kernel/sched/core.c:6637
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6696
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x555/0xaf0 kernel/locking/mutex.c:747
hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
hfsplus_cat_write_inode+0x1e3/0x820 fs/hfsplus/inode.c:590
write_inode fs/fs-writeback.c:1470 [inline]
__writeback_single_inode+0x75b/0x1160 fs/fs-writeback.c:1687
writeback_sb_inodes+0xad8/0x17d0 fs/fs-writeback.c:1913
__writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:1984
wb_writeback+0x47a/0xd00 fs/fs-writeback.c:2089
wb_check_old_data_flush fs/fs-writeback.c:2189 [inline]
wb_do_writeback fs/fs-writeback.c:2242 [inline]
wb_workfn+0xb66/0xec0 fs/fs-writeback.c:2270
process_one_work+0x898/0x1160 kernel/workqueue.c:2292
worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8c92bab0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8c92c2d0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
#0: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#0: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#0: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513
1 lock held by klogd/3625:
2 locks held by getty/4027:
#0: ffff88814e170098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
#1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41b/0x1380 drivers/tty/n_tty.c:2198
2 locks held by kworker/u4:6/4360:
2 locks held by kworker/u4:7/4385:
2 locks held by kworker/0:12/4524:
3 locks held by kworker/0:16/4706:
#0: ffff888017470938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1: ffffc9000c8ffd00 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#2: ffff888055681240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x26b/0x32b0 drivers/net/netdevsim/fib.c:1491
4 locks held by kworker/u4:17/5495:
#0: ffff8881426cf938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1: ffffc90003667d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#2: ffff8880512dc0e0 (&type->s_umount_key#94){++++}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:415
#3: ffff88805594e0b0 (&tree->tree_lock#2){+.+.}-{3:3}, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
4 locks held by syz.4.230/5557:
2 locks held by syz.5.409/6400:
#0: ffff8880512dc0e0 (&type->s_umount_key#94){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x19c/0x9e0 fs/fs-writeback.c:2748
2 locks held by syz.5.409/6402:
#0: ffff8880512dc0e0 (&type->s_umount_key#94){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x19c/0x9e0 fs/fs-writeback.c:2748
2 locks held by syz.5.409/6404:
#0: ffff8880512dc0e0 (&type->s_umount_key#94){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x19c/0x9e0 fs/fs-writeback.c:2748
2 locks held by syz.5.409/6406:
#0: ffff8880512dc0e0 (&type->s_umount_key#94){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x19c/0x9e0 fs/fs-writeback.c:2748
2 locks held by syz.5.409/6407:
#0: ffff8880512dc0e0 (&type->s_umount_key#94){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x19c/0x9e0 fs/fs-writeback.c:2748
2 locks held by syz.5.409/6408:
#0: ffff8880512dc0e0 (&type->s_umount_key#94){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x19c/0x9e0 fs/fs-writeback.c:2748
2 locks held by syz.5.409/6409:
#0: ffff8880512dc0e0 (&type->s_umount_key#94){++++}-{3:3}, at: iterate_supers+0xa4/0x1d0 fs/super.c:755
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: bdi_down_write_wb_switch_rwsem fs/fs-writeback.c:362 [inline]
#1: ffff88802449c7d0 (&bdi->wb_switch_rwsem){+.+.}-{3:3}, at: sync_inodes_sb+0x19c/0x9e0 fs/fs-writeback.c:2748
2 locks held by udevd/6767:
4 locks held by syz-executor/7081:
1 lock held by syz.6.570/7470:
1 lock held by syz.8.577/7490:
1 lock held by syz.7.578/7499:
2 locks held by syz.7.578/7502:
2 locks held by dhcpcd-run-hook/7505:

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 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+0x168/0x22e lib/dump_stack.c:106
nmi_cpu_backtrace+0x3f4/0x470 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
watchdog+0xeee/0xf30 kernel/hung_task.c:377
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4576 Comm: kworker/u4:15 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: phy7 ieee80211_iface_work
RIP: 0010:unwind_next_frame+0xb3d/0x20b0 arch/x86/kernel/unwind_orc.c:544
Code: 00 fc ff df 48 8b 44 24 28 42 80 3c 28 00 4c 8b 74 24 08 74 08 4c 89 f7 e8 c0 a1 98 00 4d 89 3e 48 8b 44 24 50 42 80 3c 28 00 <4c> 8b 74 24 58 4c 8b bc 24 80 00 00 00 48 8b 6c 24 30 74 08 4c 89
RSP: 0018:ffffc9000544ed90 EFLAGS: 00000246
RAX: 1ffff92000a89dd4 RBX: ffffc9000544ee68 RCX: 1ffff92000a89d01
RDX: ffffc9000544f350 RSI: ffffffff8e6cf010 RDI: ffffc9000544f348
RBP: ffffc9000544f348 R08: 0000000000000001 R09: 0000000000000003
R10: fffff52000a89dd9 R11: 1ffff92000a89dd7 R12: 1ffff92000a89dce
R13: dffffc0000000000 R14: ffffc9000544eeb0 R15: ffffffff896eff0f
FS: 0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f90a0599000 CR3: 0000000042efd000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
kasan_save_stack+0x3a/0x60 mm/kasan/common.c:45
__kasan_record_aux_stack+0xb2/0xc0 mm/kasan/generic.c:486
kvfree_call_rcu+0x108/0x870 kernel/rcu/tree.c:3405
cfg80211_update_known_bss+0x178/0xa20 net/wireless/scan.c:-1
cfg80211_bss_update+0x15f/0x2250 net/wireless/scan.c:1853
cfg80211_inform_single_bss_frame_data net/wireless/scan.c:2512 [inline]
cfg80211_inform_bss_frame_data+0x9f4/0x1370 net/wireless/scan.c:2545
ieee80211_bss_info_update+0x734/0xbc0 net/mac80211/scan.c:190
ieee80211_rx_bss_info net/mac80211/ibss.c:1120 [inline]
ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1609 [inline]
ieee80211_ibss_rx_queued_mgmt+0x17b4/0x2b10 net/mac80211/ibss.c:1638
ieee80211_iface_process_skb net/mac80211/iface.c:1679 [inline]
ieee80211_iface_work+0x726/0xc80 net/mac80211/iface.c:1733
process_one_work+0x898/0x1160 kernel/workqueue.c:2292
worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>


---
This report is generated by a bot. It may contain errors.
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If the report is already addressed, let syzbot know by replying with:
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If you want to overwrite report's subsystems, reply with:
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If the report is a duplicate of another one, reply with:
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If you want to undo deduplication, reply with:
#syz undup

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 50cbba13faa2 Linux 6.1.159
git tree: linux-6.1.y

console output: https://syzkaller.appspot.com/x/log.txt?x=17d4489a580000

kernel config: https://syzkaller.appspot.com/x/.config?x=6a5cbd268406bf43
dashboard link: https://syzkaller.appspot.com/bug?extid=b797a2c255e4b0845444
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1669a89a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17fa849a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/50ceb00b1b39/disk-50cbba13.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ebb8883b9a29/vmlinux-50cbba13.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7edc2a795f03/bzImage-50cbba13.xz

mounted in repro: https://storage.googleapis.com/syzbot-assets/c3bad355b1f2/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b797a2...@syzkaller.appspotmail.com

INFO: task kworker/u4:1:11 blocked for more than 143 seconds.

Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

task:kworker/u4:1 state:D
stack:24552 pid:11 ppid:2 flags:0x00004000
Workqueue: writeback wb_workfn
(flush-7:0)

Call Trace:
<TASK>
context_switch kernel/sched/core.c:5244 [inline]
__schedule+0x10ec/0x40b0 kernel/sched/core.c:6561
schedule+0xb9/0x180 kernel/sched/core.c:6637
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6696
__mutex_lock_common kernel/locking/mutex.c:679 [inline]
__mutex_lock+0x555/0xaf0 kernel/locking/mutex.c:747
hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
hfsplus_cat_write_inode+0x1e3/0x820 fs/hfsplus/inode.c:590
write_inode fs/fs-writeback.c:1470 [inline]
__writeback_single_inode+0x75b/0x1160 fs/fs-writeback.c:1687
writeback_sb_inodes+0xad8/0x17d0 fs/fs-writeback.c:1913
__writeback_inodes_wb+0x12a/0x3f0 fs/fs-writeback.c:1984
wb_writeback+0x47a/0xd00 fs/fs-writeback.c:2089

wb_check_background_flush fs/fs-writeback.c:2155 [inline]
wb_do_writeback fs/fs-writeback.c:2243 [inline]
wb_workfn+0xbdd/0xec0 fs/fs-writeback.c:2270

process_one_work+0x898/0x1160 kernel/workqueue.c:2292
worker_thread+0xaa2/0x1250 kernel/workqueue.c:2439
kthread+0x29d/0x330 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>

Showing all locks held in the system:

2 locks held by kworker/u4:0/9:
#0: ffff888017479138 ((wq_completion)events_unbound

){+.+.}-{0:0}
, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1:

ffffc900000e7d00
(
(linkwatch_work).work

){+.+.}-{0:0}
, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267

4 locks held by kworker/u4:1/11:
#0:
ffff888141a6e138
(
(wq_completion)writeback

){+.+.}-{0:0}
, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267

#1: ffffc90000107d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#2:
ffff888073e5a0e0
(
&type->s_umount_key
#53
){.+.+}-{3:3}

, at: trylock_super+0x1c/0xf0 fs/super.c:415
#3:

ffff8880187420b0
(
&tree->tree_lock

){+.+.}-{3:3}
, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28

1 lock held by rcu_tasks_kthre/12:
#0: ffffffff8c92bab0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
#0: ffffffff8c92c2d0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xf00 kernel/rcu/tasks.h:517

1 lock held by khungtaskd/27:

#0: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
#0: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
#0: ffffffff8c92b120 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6513

4 locks held by kworker/u4:3/46:
#0: ffff888141a6e138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1: ffffc90000b77d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#2: ffff8881426ec0e0 (&type->s_umount_key#53){.+.+}-{3:3}, at: trylock_super+0x1c/0xf0 fs/super.c:415
#3: ffff888075e8a0b0 (&tree->tree_lock){+.+.}-{3:3}, at: hfsplus_find_init+0x150/0x1c0 fs/hfsplus/bfind.c:28
5 locks held by kworker/u4:4/62:
3 locks held by kworker/0:2/127:
#0: ffff88814caead38 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#1: ffffc90002db7d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7a1/0x1160 kernel/workqueue.c:2267
#2: ffffffff8db3b3a8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xc4/0x14d0 net/ipv6/addrconf.c:4131
2 locks held by getty/4024:
#0:
ffff8880306ac098


---
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