INFO: task hung in f2fs_file_write_iter (8)

Status: auto-obsoleted due to no activity on 2026/07/25 11:18
Subsystems: f2fs
Labels: prio:low
[Documentation on labels]
First crash: 119d, last: 118d
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
986c70f7 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ INFO: task hung in f2fs_file_write_iter (8) 2026/05/24 12:47 2026/05/24 12:47 2026/05/24 13:42 c69befb3
Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in f2fs_file_write_iter (3) f2fs 1 4 846d 910d 0/29 auto-obsoleted due to no activity on 2024/07/28 01:00
upstream INFO: task hung in f2fs_file_write_iter (4) f2fs 1 2 706d 710d 0/29 auto-obsoleted due to no activity on 2024/12/14 14:52
upstream INFO: task hung in f2fs_file_write_iter (7) f2fs 1 2 212d 225d 0/29 auto-obsoleted due to no activity on 2026/04/22 02:55
upstream INFO: task hung in f2fs_file_write_iter (6) f2fs 1 1 325d 325d 0/29 auto-obsoleted due to no activity on 2025/12/30 22:07
linux-4.19 INFO: task hung in f2fs_file_write_iter f2fs 1 5 1268d 1371d 0/1 upstream: reported on 2022/11/20 07:00
upstream INFO: task hung in f2fs_file_write_iter f2fs 1 5 1171d 1267d 0/29 auto-obsoleted due to no activity on 2023/09/06 20:28
upstream INFO: task hung in f2fs_file_write_iter (2) f2fs 1 1 1010d 1010d 0/29 auto-obsoleted due to no activity on 2024/02/14 19:21
upstream INFO: task hung in f2fs_file_write_iter (5) f2fs 1 3 418d 487d 0/29 auto-obsoleted due to no activity on 2025/09/28 14:58

Sample crash report:
INFO: task syz.4.1141:19514 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.1141      state:D stack:27672 pid:19514 tgid:19487 ppid:17124  task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5387 [inline]
 __schedule+0x1681/0x54c0 kernel/sched/core.c:7188
 __schedule_loop kernel/sched/core.c:7267 [inline]
 rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7563
 rt_mutex_slowlock_block kernel/locking/rtmutex.c:1662 [inline]
 __rt_mutex_slowlock kernel/locking/rtmutex.c:1739 [inline]
 __rt_mutex_slowlock_locked+0x1f28/0x2550 kernel/locking/rtmutex.c:1779
 rt_mutex_slowlock+0xbd/0x170 kernel/locking/rtmutex.c:1819
 __rt_mutex_lock kernel/locking/rtmutex.c:1834 [inline]
 rwbase_write_lock+0x14d/0x730 kernel/locking/rwbase_rt.c:245
 inode_lock include/linux/fs.h:1029 [inline]
 f2fs_file_write_iter+0x25a/0x24c0 fs/f2fs/file.c:5241
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x629/0xba0 fs/read_write.c:688
 ksys_write+0x156/0x270 fs/read_write.c:740
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4aeb02cdd9
RSP: 002b:00007f4ae9244028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f4aeb2a6180 RCX: 00007f4aeb02cdd9
RDX: 0000000000000050 RSI: 0000200000000500 RDI: 0000000000000006
RBP: 00007f4aeb0c2d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4aeb2a6218 R14: 00007f4aeb2a6180 R15: 00007ffc6c929348
 </TASK>

Showing all locks held in the system:
5 locks held by kworker/u8:1/13:
1 lock held by khungtaskd/37:
 #0: ffffffff8dfc8140 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8dfc8140 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8dfc8140 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by kworker/u8:10/1411:
 #0: ffff88801a074938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3277 [inline]
 #0: ffff88801a074938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3385
 #1: ffffc9000672fc40 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3278 [inline]
 #1: ffffc9000672fc40 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3385
1 lock held by dhcpcd/5256:
 #0: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #0: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: devinet_ioctl+0x32b/0x1b30 net/ipv4/devinet.c:1120
2 locks held by getty/5348:
 #0: ffff88803668b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90003cbe2e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x462/0x13a0 drivers/tty/n_tty.c:2211
4 locks held by kworker/u8:15/6850:
 #0: ffff88801b290938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3277 [inline]
 #0: ffff88801b290938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3385
 #1: ffffc900057c7c40 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3278 [inline]
 #1: ffffc900057c7c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3385
 #2: ffffffff8f347140 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf4/0x800 net/core/net_namespace.c:673
 #3: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: cfg80211_pernet_exit+0x19/0x120 net/wireless/core.c:1810
3 locks held by kworker/u8:22/9529:
 #0: ffff88803145e138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3277 [inline]
 #0: ffff88803145e138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3385
 #1: ffffc900060bfc40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3278 [inline]
 #1: ffffc900060bfc40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3385
 #2: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #2: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x124/0x1680 net/ipv6/addrconf.c:4206
2 locks held by kworker/u8:0/16976:
 #0: ffff88801a074938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3277 [inline]
 #0: ffff88801a074938 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3385
 #1: ffffc90004087c40 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3278 [inline]
 #1: ffffc90004087c40 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3385
4 locks held by kworker/u8:4/17751:
 #0: ffff88801f2c7938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3277 [inline]
 #0: ffff88801f2c7938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860 kernel/workqueue.c:3385
 #1: ffffc90003d47c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3278 [inline]
 #1: ffffc90003d47c40 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860 kernel/workqueue.c:3385
 #2: ffff888062a120d0 (&type->s_umount_key#113){++++}-{4:4}, at: super_trylock_shared+0x20/0xf0 fs/super.c:565
 #3: ffff88808a7eda98 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write fs/f2fs/f2fs.h:2411 [inline]
 #3: ffff88808a7eda98 (&sbi->gc_lock){+.+.}-{4:4}, at: f2fs_down_write_trace+0x3e/0x1d0 fs/f2fs/checkpoint.c:180
5 locks held by syz.4.1141/19488:
3 locks held by syz.4.1141/19514:
 #0: ffff888037130128 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1261
 #1: ffff888062a12480 (sb_writers#28){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2724 [inline]
 #1: ffff888062a12480 (sb_writers#28){.+.+}-{0:0}, at: vfs_write+0x22d/0xba0 fs/read_write.c:684
 #2: ffff8880625fceb8 (&sb->s_type->i_mutex_key#40){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:1029 [inline]
 #2: ffff8880625fceb8 (&sb->s_type->i_mutex_key#40){+.+.}-{4:4}, at: f2fs_file_write_iter+0x25a/0x24c0 fs/f2fs/file.c:5241
1 lock held by syz-executor/20067:
 #0: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
 #0: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x41/0x1c0 drivers/net/tun.c:3438
1 lock held by syz-executor/20078:
 #0: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: tun_detach drivers/net/tun.c:634 [inline]
 #0: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x41/0x1c0 drivers/net/tun.c:3438
2 locks held by syz-executor/20123:
7 locks held by syz-executor/20251:
 #0: ffff888036c9e480 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2724 [inline]
 #0: ffff888036c9e480 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22d/0xba0 fs/read_write.c:684
 #1: ffff8880644af878 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1df/0x540 fs/kernfs/file.c:343
 #2: ffff8880295cbc38 (kn->active#53){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #2: ffff8880295cbc38 (kn->active#53){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x232/0x540 fs/kernfs/file.c:344
 #3: ffffffff8ebcea78 (nsim_bus_dev_list_lock){+.+.}-{4:4}, at: new_device_store+0x13c/0x710 drivers/net/netdevsim/bus.c:184
 #4: ffff88802a50a160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:1040 [inline]
 #4: ffff88802a50a160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x88/0x450 drivers/base/dd.c:1076
 #5: ffff888060da0310 (&devlink->lock_key#101){+.+.}-{4:4}, at: nsim_drv_probe+0xc9/0xc30 drivers/net/netdevsim/dev.c:1658
 #6: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
 #6: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_dev_lock+0x257/0x2f0 net/core/dev.c:2162
2 locks held by syz-executor/20341:
 #0: ffffffff8eabeec8 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8eabeec8 (&ops->srcu#2){.+.+}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8eabeec8 (&ops->srcu#2){.+.+}-{0:0}, at: rtnl_link_ops_get+0x23/0x250 net/core/rtnetlink.c:570
 #1: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #1: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #1: ffffffff8f355e78 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x883/0x1bb0 net/core/rtnetlink.c:4108
1 lock held by modprobe/20406:
1 lock held by modprobe/20407:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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:162 [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:353 [inline]
 watchdog+0xfd3/0x1030 kernel/hung_task.c:561
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 13 Comm: kworker/u8:1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Workqueue: bat_events batadv_tt_purge
RIP: 0010:debug_spin_unlock kernel/locking/spinlock_debug.c:102 [inline]
RIP: 0010:do_raw_spin_unlock+0x7b/0x210 kernel/locking/spinlock_debug.c:141
Code: c1 e8 03 42 0f b6 04 20 84 c0 0f 85 47 01 00 00 83 3b 00 0f 84 bd 00 00 00 4c 8d 73 10 4d 89 f5 49 c1 ed 03 43 80 7c 25 00 00 <74> 08 4c 89 f7 e8 db 76 8a 00 65 48 8b 05 ab 34 c9 10 49 39 06 0f
RSP: 0018:ffffc90000127870 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff888037a11000 RCX: ffffffff81a0fb1d
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff888037a11000
RBP: ffffc900001279a8 R08: ffff888037a11003 R09: 1ffff11006f42200
R10: dffffc0000000000 R11: ffffed1006f42201 R12: dffffc0000000000
R13: 1ffff11006f42202 R14: ffff888037a11010 R15: ffff888037a11000
FS:  0000000000000000(0000) GS:ffff88812627d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6b831e7e20 CR3: 0000000061506000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:177 [inline]
 _raw_spin_unlock_irqrestore+0x23/0x80 kernel/locking/spinlock.c:198
 unlock_rt_mutex_safe kernel/locking/rtmutex.c:350 [inline]
 rt_mutex_slowunlock+0x4a7/0x8b0 kernel/locking/rtmutex.c:1463
 spin_unlock_bh include/linux/spinlock_rt.h:115 [inline]
 batadv_tt_local_purge+0x2ed/0x380 net/batman-adv/translation-table.c:1320
 batadv_tt_purge+0x35/0xa10 net/batman-adv/translation-table.c:3514
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0xb5d/0x1860 kernel/workqueue.c:3385
 worker_thread+0xa53/0xfc0 kernel/workqueue.c:3466
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/26 11:14 upstream 897d54018cc9 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in f2fs_file_write_iter
2026/04/25 11:48 upstream 27d128c1cff6 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in f2fs_file_write_iter
* Struck through repros no longer work on HEAD.