[v5.15] INFO: task hung in f2fs_stop_gc_thread

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cc5ec8769306 Linux 5.15.196
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=107c2a92580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=271ecd34c43208563db0
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/c71c660545b2/disk-cc5ec876.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4f011826cca6/vmlinux-cc5ec876.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8ccd1a2c3f8c/bzImage-cc5ec876.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+271ecd...@syzkaller.appspotmail.com

INFO: task syz.0.822:8047 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.822 state:D stack:27600 pid: 8047 ppid: 4191 flags:0x00004004
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_timeout+0x97/0x280 kernel/time/timer.c:1890
do_wait_for_common+0x29a/0x440 kernel/sched/completion.c:85
__wait_for_common kernel/sched/completion.c:106 [inline]
wait_for_common kernel/sched/completion.c:117 [inline]
wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
kthread_stop+0x16e/0x540 kernel/kthread.c:666
f2fs_stop_gc_thread+0x61/0xa0 fs/f2fs/gc.c:186
f2fs_ioc_shutdown fs/f2fs/file.c:2308 [inline]
__f2fs_ioctl+0x6732/0xc370 fs/f2fs/file.c:4221
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
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: 0033:0x7f633c9506c9
RSP: 002b:00007f633ab75038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f633cba7180 RCX: 00007f633c9506c9
RDX: 0000200000000080 RSI: 000000008004587d RDI: 0000000000000006
RBP: 00007f633c9d2f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f633cba7218 R14: 00007f633cba7180 R15: 00007fff1dd37148
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8c11c760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
6 locks held by kworker/0:3/1336:
#0: ffff8881423de938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
#1: ffffc90005097d00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
#2: ffff8881480cf220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
#2: ffff8881480cf220 (&dev->mutex){....}-{3:3}, at: hub_event+0x1a7/0x5560 drivers/usb/core/hub.c:5827
#3: ffff8881480e25c0 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3168 [inline]
#3: ffff8881480e25c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5393 [inline]
#3: ffff8881480e25c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5637 [inline]
#3: ffff8881480e25c0 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5799 [inline]
#3: ffff8881480e25c0 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x30f2/0x5560 drivers/usb/core/hub.c:5881
#4: ffff8881477a8a68 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5394 [inline]
#4: ffff8881477a8a68 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5637 [inline]
#4: ffff8881477a8a68 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5799 [inline]
#4: ffff8881477a8a68 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x3124/0x5560 drivers/usb/core/hub.c:5881
#5: ffffffff8cb98350 (ehci_cf_port_reset_rwsem){.+.+}-{3:3}, at: hub_port_reset+0x14f/0x18d0 drivers/usb/core/hub.c:3030
2 locks held by getty/3946:
#0: ffff88814cad4098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
1 lock held by syz-executor/7849:
1 lock held by syz.0.822/8047:
#0: ffff88807d094460 (sb_writers#31){.+.+}-{0:0}, at: mnt_want_write_file+0x5c/0x200 fs/namespace.c:430
3 locks held by syz.9.1378/10720:

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 7278 Comm: kworker/u4:18 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: phy16 ieee80211_iface_work
RIP: 0010:get_current arch/x86/include/asm/current.h:15 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x4/0x60 kernel/kcov.c:205
Code: 84 00 00 00 00 00 53 48 89 fb e8 17 00 00 00 48 8b 3d 50 d3 f1 0b 48 89 de 5b e9 57 9e 43 00 00 00 cc cc 00 00 cc 48 8b 04 24 <65> 48 8b 0d a4 a3 8a 7e 65 8b 15 a5 a3 8a 7e 81 e2 00 01 ff 00 74
RSP: 0018:ffffc900035cfba0 EFLAGS: 00000282
RAX: ffffffff87cfd698 RBX: ffff888057099dc0 RCX: 5069d0290163a100
RDX: dffffc0000000000 RSI: ffffffff8a0b1c60 RDI: ffff888057099dc0
RBP: ffff888057099dc0 R08: dffffc0000000000 R09: fffffbfff1ff7c3a
R10: fffffbfff1ff7c3a R11: 1ffffffff1ff7c39 R12: ffff88805a4b0c80
R13: 0000000000000080 R14: 0000000000000001 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa478801ad8 CR3: 0000000079473000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
kfree_skbmem+0x18/0x180 net/core/skbuff.c:695
kfree_skb include/linux/skbuff.h:1118 [inline]
ieee80211_iface_work+0x798/0xc60 net/mac80211/iface.c:1515
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>


---
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 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: cc5ec8769306 Linux 5.15.196
git tree: linux-5.15.y

console output: https://syzkaller.appspot.com/x/log.txt?x=17693bcd980000

kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=271ecd34c43208563db0
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=15ee2a92580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13ee2a92580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c71c660545b2/disk-cc5ec876.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4f011826cca6/vmlinux-cc5ec876.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8ccd1a2c3f8c/bzImage-cc5ec876.xz

mounted in repro: https://storage.googleapis.com/syzbot-assets/e871bae14840/mount_2.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=131a117c580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+271ecd...@syzkaller.appspotmail.com

INFO: task syz.0.18:4383 blocked for more than 143 seconds.

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

task:syz.0.18 state:D stack:28256 pid: 4383 ppid: 4309 flags:0x00004004

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_timeout+0x97/0x280 kernel/time/timer.c:1890
do_wait_for_common+0x29a/0x440 kernel/sched/completion.c:85
__wait_for_common kernel/sched/completion.c:106 [inline]
wait_for_common kernel/sched/completion.c:117 [inline]
wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
kthread_stop+0x16e/0x540 kernel/kthread.c:666
f2fs_stop_gc_thread+0x61/0xa0 fs/f2fs/gc.c:186
f2fs_ioc_shutdown fs/f2fs/file.c:2308 [inline]
__f2fs_ioctl+0x6732/0xc370 fs/f2fs/file.c:4221
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
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: 0033:0x7fa3b72366c9
RSP: 002b:00007fa3b6884038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fa3b748d090 RCX: 00007fa3b72366c9
RDX: 0000200000000080 RSI: 000000008004587d RDI: 0000000000000004
RBP: 00007fa3b72b8f91 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007fa3b748d128 R14: 00007fa3b748d090 R15: 00007ffd800bb438

</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8c11c760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30

2 locks held by kworker/u4:4/3058:
#0: ffff8880b903a358 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475
#1: ffff8880b9027888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x495/0x810 kernel/sched/psi.c:882
2 locks held by getty/3948:
#0: ffff88814d01c098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc90002d032e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
1 lock held by syz.0.18/4383:
#0: ffff88807ac5c460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x5c/0x200 fs/namespace.c:430
1 lock held by syz.1.22/4436:
#0: ffff88807401a460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x5c/0x200 fs/namespace.c:430
1 lock held by syz.2.23/4463:
#0: ffff8880282b6460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x5c/0x200 fs/namespace.c:430
1 lock held by syz.3.25/4493:
#0: ffff88802a320460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x5c/0x200 fs/namespace.c:430
1 lock held by syz.4.26/4526:
#0: ffff88801f42a460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x5c/0x200 fs/namespace.c:430
1 lock held by syz.5.27/4571:
#0: ffff88804a9a4460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x5c/0x200 fs/namespace.c:430
1 lock held by syz.6.36/4659:
#0: ffff88802d6e4460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x5c/0x200 fs/namespace.c:430
1 lock held by syz.7.40/4714:
#0: ffff888077442460 (sb_writers#13){.+.+}-{0:0}, at: mnt_want_write_file+0x5c/0x200 fs/namespace.c:430

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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 1 to CPUs 0:
NMI backtrace for cpu 0

CPU: 0 PID: 4332 Comm: kworker/0:11 Not tainted syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025

Workqueue: events_power_efficient neigh_periodic_work
RIP: 0010:lock_is_held_type+0x1/0x190 kernel/locking/lockdep.c:5651
Code: c0 03 00 75 d6 48 c7 c7 00 1b 0b 8a 48 c7 c6 40 1b 0b 8a e8 c1 37 f5 ff 0f 0b eb bf e8 98 fd ff ff 0f 1f 84 00 00 00 00 00 55 <41> 57 41 56 41 55 41 54 53 48 83 ec 10 65 48 8b 04 25 28 00 00 00
RSP: 0018:ffffc900031ffba8 EFLAGS: 00000202
RAX: ffffffff87dab0f7 RBX: 0000000000000001 RCX: ffff88802b528000
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffffffff8d3381f0
RBP: 0000000000000000 R08: 0000000000000004 R09: 0000000000000003
R10: fffff5200063ff68 R11: 1ffff9200063ff68 R12: ffff888077402c08
R13: dffffc0000000000 R14: 000000000000000a R15: 0000000100000040

FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000561c5dfd4168 CR3: 00000000299d9000 CR4: 00000000003506f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>

lock_is_held include/linux/lockdep.h:287 [inline]
neigh_periodic_work+0x42a/0xc70 net/core/neighbour.c:921

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>


---

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