Re: [syzbot] [f2fs?] INFO: task hung in f2fs_release_file (3)

syzbot
2025-12-06T11:00:03Z

INFO: task syz.0.17:6630 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17 state:D stack:26840 pid:6630 tgid:6630 ppid:6466 task_flags:0x400040 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1480/0x50a0 kernel/sched/core.c:6863
__schedule_loop kernel/sched/core.c:6945 [inline]
rt_mutex_schedule+0x77/0xf0 kernel/sched/core.c:7241
rt_mutex_slowlock_block kernel/locking/rtmutex.c:1647 [inline]
__rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
__rt_mutex_slowlock_locked+0x1dfe/0x25e0 kernel/locking/rtmutex.c:1760
rt_mutex_slowlock+0xb5/0x160 kernel/locking/rtmutex.c:1800
__rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
rwbase_write_lock+0x14f/0x750 kernel/locking/rwbase_rt.c:244
inode_lock include/linux/fs.h:1027 [inline]
f2fs_release_file+0xe3/0x150 fs/f2fs/file.c:2063
__fput+0x45b/0xa80 fs/file_table.c:468
task_work_run+0x1d4/0x260 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
exit_to_user_mode_loop+0xff/0x4f0 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x2e3/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f255a87f749
RSP: 002b:00007ffd480f4778 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f255aad7da0 RCX: 00007f255a87f749
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f255aad7da0 R08: 0000000000000000 R09: 00000006480f4a6f
R10: 00007f255aad7cb0 R11: 0000000000000246 R12: 0000000000027f51
R13: 00007ffd480f4870 R14: ffffffffffffffff R15: 00007ffd480f4890
</TASK>
INFO: task syz.0.17:6631 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17 state:D stack:23840 pid:6631 tgid:6630 ppid:6466 task_flags:0x400140 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1480/0x50a0 kernel/sched/core.c:6863
__schedule_loop kernel/sched/core.c:6945 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6960
schedule_timeout+0x9a/0x270 kernel/time/sleep_timeout.c:75
do_wait_for_common kernel/sched/completion.c:100 [inline]
__wait_for_common kernel/sched/completion.c:121 [inline]
wait_for_common kernel/sched/completion.c:132 [inline]
wait_for_completion+0x2bf/0x5d0 kernel/sched/completion.c:153
f2fs_issue_checkpoint+0x382/0x610 fs/f2fs/checkpoint.c:-1
f2fs_unlink+0x5cb/0xa80 fs/f2fs/namei.c:603
vfs_unlink+0x386/0x650 fs/namei.c:5369
do_unlinkat+0x2cf/0x570 fs/namei.c:5439
__do_sys_unlinkat fs/namei.c:5469 [inline]
__se_sys_unlinkat fs/namei.c:5462 [inline]
__x64_sys_unlinkat+0xd3/0xf0 fs/namei.c:5462
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f255a87f749
RSP: 002b:00007f2559ee6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 00007f255aad5fa0 RCX: 00007f255a87f749
RDX: 0000000000000000 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007f255a903f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f255aad6038 R14: 00007f255aad5fa0 R15: 00007ffd480f4618
</TASK>
INFO: task syz.1.18:6657 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.18 state:D stack:26840 pid:6657 tgid:6657 ppid:6637 task_flags:0x400040 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1480/0x50a0 kernel/sched/core.c:6863
__schedule_loop kernel/sched/core.c:6945 [inline]
rt_mutex_schedule+0x77/0xf0 kernel/sched/core.c:7241
rt_mutex_slowlock_block kernel/locking/rtmutex.c:1647 [inline]
__rt_mutex_slowlock kernel/locking/rtmutex.c:1721 [inline]
__rt_mutex_slowlock_locked+0x1dfe/0x25e0 kernel/locking/rtmutex.c:1760
rt_mutex_slowlock+0xb5/0x160 kernel/locking/rtmutex.c:1800
__rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
rwbase_write_lock+0x14f/0x750 kernel/locking/rwbase_rt.c:244
inode_lock include/linux/fs.h:1027 [inline]
f2fs_release_file+0xe3/0x150 fs/f2fs/file.c:2063
__fput+0x45b/0xa80 fs/file_table.c:468
task_work_run+0x1d4/0x260 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
exit_to_user_mode_loop+0xff/0x4f0 kernel/entry/common.c:75
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
do_syscall_64+0x2e3/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0733fcf749
RSP: 002b:00007ffd49167788 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f0734227da0 RCX: 00007f0733fcf749
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f0734227da0 R08: 0000000000000000 R09: 0000000649167a7f
R10: 00007f0734227cb0 R11: 0000000000000246 R12: 000000000002c7c8
R13: 00007ffd49167880 R14: ffffffffffffffff R15: 00007ffd491678a0
</TASK>
INFO: task syz.1.18:6658 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.1.18 state:D stack:24488 pid:6658 tgid:6657 ppid:6637 task_flags:0x400140 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5256 [inline]
__schedule+0x1480/0x50a0 kernel/sched/core.c:6863
__schedule_loop kernel/sched/core.c:6945 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6960
schedule_timeout+0x9a/0x270 kernel/time/sleep_timeout.c:75
do_wait_for_common kernel/sched/completion.c:100 [inline]
__wait_for_common kernel/sched/completion.c:121 [inline]
wait_for_common kernel/sched/completion.c:132 [inline]
wait_for_completion+0x2bf/0x5d0 kernel/sched/completion.c:153
f2fs_issue_checkpoint+0x382/0x610 fs/f2fs/checkpoint.c:-1
f2fs_unlink+0x5cb/0xa80 fs/f2fs/namei.c:603
vfs_unlink+0x386/0x650 fs/namei.c:5369
do_unlinkat+0x2cf/0x570 fs/namei.c:5439
__do_sys_unlinkat fs/namei.c:5469 [inline]
__se_sys_unlinkat fs/namei.c:5462 [inline]
__x64_sys_unlinkat+0xd3/0xf0 fs/namei.c:5462
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0733fcf749
RSP: 002b:00007f0733636038 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 00007f0734225fa0 RCX: 00007f0733fcf749
RDX: 0000000000000000 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007f0734053f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0734226038 R14: 00007f0734225fa0 R15: 00007ffd49167628
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/38:
#0: ffffffff8d5aecc0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8d5aecc0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8d5aecc0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:3/50:
#0: ffff888140462938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
#0: ffff888140462938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340
#1: ffffc90000bc7b80 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
#1: ffffc90000bc7b80 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340
#2: ffff8880339a40d0 (&type->s_umount_key#55){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563
3 locks held by kworker/u8:5/153:
#0: ffff888140462938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
#0: ffff888140462938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340
#1: ffffc90003a97b80 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
#1: ffffc90003a97b80 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340
#2: ffff888057e3a0d0 (&type->s_umount_key#55){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563
3 locks held by kworker/u8:8/1098:
#0: ffff888140462938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
#0: ffff888140462938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340
#1: ffffc90004c7fb80 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
#1: ffffc90004c7fb80 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340
#2: ffff88802ac120d0 (&type->s_umount_key#55){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563
3 locks held by kworker/u8:16/3502:
#0: ffff888140462938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
#0: ffff888140462938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340
#1: ffffc9000d517b80 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
#1: ffffc9000d517b80 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340
#2: ffff88805f73a0d0 (&type->s_umount_key#55){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563
2 locks held by getty/5564:
#0: ffff88814ded00a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc90003e8b2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x444/0x1400 drivers/tty/n_tty.c:2222
1 lock held by syz.0.17/6630:
#0: ffff888058488178 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#0: ffff888058488178 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: f2fs_release_file+0xe3/0x150 fs/f2fs/file.c:2063
3 locks held by syz.0.17/6631:
#0: ffff888057e3a480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
#1: ffff888058571478 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff888058571478 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2864 [inline]
#1: ffff888058571478 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2875 [inline]
#1: ffff888058571478 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1b2/0x570 fs/namei.c:5420
#2: ffff888058488178 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#2: ffff888058488178 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: vfs_unlink+0xef/0x650 fs/namei.c:5355
3 locks held by f2fs_ckpt-7:0/6635:
1 lock held by syz.1.18/6657:
#0: ffff8880585730f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#0: ffff8880585730f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: f2fs_release_file+0xe3/0x150 fs/f2fs/file.c:2063
3 locks held by syz.1.18/6658:
#0: ffff88805f73a480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
#1: ffff888058572778 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff888058572778 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2864 [inline]
#1: ffff888058572778 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2875 [inline]
#1: ffff888058572778 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1b2/0x570 fs/namei.c:5420
#2: ffff8880585730f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#2: ffff8880585730f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: vfs_unlink+0xef/0x650 fs/namei.c:5355
3 locks held by f2fs_ckpt-7:1/6665:
1 lock held by syz.2.19/6689:
#0: ffff88805848b0f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#0: ffff88805848b0f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: f2fs_release_file+0xe3/0x150 fs/f2fs/file.c:2063
3 locks held by syz.2.19/6690:
#0: ffff88802ac12480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
#1: ffff88805848a778 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff88805848a778 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2864 [inline]
#1: ffff88805848a778 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2875 [inline]
#1: ffff88805848a778 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1b2/0x570 fs/namei.c:5420
#2: ffff88805848b0f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#2: ffff88805848b0f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: vfs_unlink+0xef/0x650 fs/namei.c:5355
3 locks held by f2fs_ckpt-7:2/6694:
1 lock held by syz.3.20/6718:
#0: ffff88805848d6f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#0: ffff88805848d6f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: f2fs_release_file+0xe3/0x150 fs/f2fs/file.c:2063
3 locks held by syz.3.20/6719:
#0: ffff888037b64480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
#1: ffff88805848cd78 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff88805848cd78 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2864 [inline]
#1: ffff88805848cd78 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2875 [inline]
#1: ffff88805848cd78 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1b2/0x570 fs/namei.c:5420
#2: ffff88805848d6f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#2: ffff88805848d6f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: vfs_unlink+0xef/0x650 fs/namei.c:5355
2 locks held by f2fs_ckpt-7:3/6723:
1 lock held by syz.4.21/6753:
#0: ffff8880585756f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#0: ffff8880585756f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: f2fs_release_file+0xe3/0x150 fs/f2fs/file.c:2063
3 locks held by syz.4.21/6754:
#0: ffff8880339a4480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
#1: ffff888058574d78 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff888058574d78 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2864 [inline]
#1: ffff888058574d78 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2875 [inline]
#1: ffff888058574d78 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1b2/0x570 fs/namei.c:5420
#2: ffff8880585756f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#2: ffff8880585756f8 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: vfs_unlink+0xef/0x650 fs/namei.c:5355
5 locks held by f2fs_ckpt-7:4/6764:
3 locks held by kworker/u8:18/6790:
#0: ffff888140462938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3232 [inline]
#0: ffff888140462938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x1770 kernel/workqueue.c:3340
#1: ffffc90004e2fb80 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3233 [inline]
#1: ffffc90004e2fb80 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x1770 kernel/workqueue.c:3340
#2: ffff888037b640d0 (&type->s_umount_key#55){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:563
1 lock held by syz.5.22/6795:
#0: ffff88805d948178 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#0: ffff88805d948178 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: f2fs_release_file+0xe3/0x150 fs/f2fs/file.c:2063
3 locks held by syz.5.22/6796:
#0: ffff8880346ea480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
#1: ffff888058577378 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff888058577378 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2864 [inline]
#1: ffff888058577378 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2875 [inline]
#1: ffff888058577378 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1b2/0x570 fs/namei.c:5420
#2: ffff88805d948178 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#2: ffff88805d948178 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: vfs_unlink+0xef/0x650 fs/namei.c:5355
2 locks held by f2fs_ckpt-7:5/6800:
1 lock held by syz.6.23/6836:
#0: ffff88805da38178 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#0: ffff88805da38178 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: f2fs_release_file+0xe3/0x150 fs/f2fs/file.c:2063
3 locks held by syz.6.23/6837:
#0: ffff888035b9c480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
#1: ffff88805848f378 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff88805848f378 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2864 [inline]
#1: ffff88805848f378 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2875 [inline]
#1: ffff88805848f378 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1b2/0x570 fs/namei.c:5420
#2: ffff88805da38178 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#2: ffff88805da38178 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: vfs_unlink+0xef/0x650 fs/namei.c:5355
3 locks held by f2fs_ckpt-7:6/6841:
1 lock held by syz.7.24/6882:
#0: ffff88805da3a778 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#0: ffff88805da3a778 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: f2fs_release_file+0xe3/0x150 fs/f2fs/file.c:2063
3 locks held by syz.7.24/6883:
#0: ffff88805baf2480 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:499
#1: ffff88805da39df8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff88805da39df8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_dirop fs/namei.c:2864 [inline]
#1: ffff88805da39df8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: start_dirop fs/namei.c:2875 [inline]
#1: ffff88805da39df8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: do_unlinkat+0x1b2/0x570 fs/namei.c:5420
#2: ffff88805da3a778 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1027 [inline]
#2: ffff88805da3a778 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: vfs_unlink+0xef/0x650 fs/namei.c:5355
2 locks held by f2fs_ckpt-7:7/6889:

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

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 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:332 [inline]
watchdog+0xf3c/0xf80 kernel/hung_task.c:495
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 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: 6889 Comm: f2fs_ckpt-7:7 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:check_preemption_disabled+0x12/0x120 lib/smp_processor_id.c:13
Code: 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 41 56 53 48 83 ec 10 65 48 8b 05 1e f2 e5 06 <48> 89 44 24 08 65 8b 05 26 f2 e5 06 65 8b 0d 1b f2 e5 06 f7 c1 ff
RSP: 0018:ffffc900052df610 EFLAGS: 00000082
RAX: 6dac46a9b706f000 RBX: 00000000ffffffff RCX: dffffc0000000000
RDX: dffffc0000000000 RSI: ffffffff8ce10cff RDI: ffffffff8b3ede60
RBP: 00000000ffffffff R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000a5bec0 R12: 0000000000000046
R13: ffff888024e55ac0 R14: ffff8880348bc360 R15: ffff888024e55ac0
FS: 0000000000000000(0000) GS:ffff888126e52000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0178684f98 CR3: 000000000d3a8000 CR4: 00000000003526f0
Call Trace:
<TASK>
lockdep_recursion_inc kernel/locking/lockdep.c:465 [inline]
lock_is_held_type+0x79/0x190 kernel/locking/lockdep.c:5939
lock_is_held include/linux/lockdep.h:249 [inline]
try_to_take_rt_mutex+0x4f/0xac0 kernel/locking/rtmutex.c:1090
__rt_mutex_slowtrylock kernel/locking/rtmutex.c:1360 [inline]
rt_mutex_slowtrylock kernel/locking/rtmutex.c:1393 [inline]
rt_mutex_try_acquire kernel/locking/rtmutex.c:320 [inline]
__rt_mutex_lock kernel/locking/rtmutex.c:1812 [inline]
rwbase_write_lock+0xce/0x750 kernel/locking/rwbase_rt.c:244
f2fs_down_write fs/f2fs/f2fs.h:2294 [inline]
f2fs_lock_all fs/f2fs/f2fs.h:2374 [inline]
block_operations fs/f2fs/checkpoint.c:1221 [inline]
f2fs_write_checkpoint+0x566/0x26a0 fs/f2fs/checkpoint.c:1689
__write_checkpoint_sync fs/f2fs/checkpoint.c:1813 [inline]
__checkpoint_and_complete_reqs+0xdf/0x3d0 fs/f2fs/checkpoint.c:1832
issue_checkpoint_thread+0xd9/0x260 fs/f2fs/checkpoint.c:1864
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
</TASK>

Tested on:

commit: 416f99c3 Merge tag 'driver-core-6.19-rc1' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=105746c2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8c04d4527fc98ffa
dashboard link: https://syzkaller.appspot.com/bug?extid=4235e4d7b6fd75704528
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=150cbc1a580000