syzbot


INFO: task hung in f2fs_stop_gc_thread

Status: upstream: reported C repro on 2025/12/13 07:44
Reported-by: syzbot+279cf538f28759858216@syzkaller.appspotmail.com
First crash: 80d, last: 27d
Bug presence (1)
Date Name Commit Repro Result
2026/02/18 upstream (ToT) 2961f841b025 C Failed due to an error; will retry later
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: task hung in f2fs_stop_gc_thread origin:lts-only 1 C error 10 15d 115d 0/3 upstream: reported C repro on 2025/11/07 22:55
upstream INFO: task hung in f2fs_stop_gc_thread f2fs 1 24 472d 586d 0/29 auto-obsoleted due to no activity on 2025/01/22 18:30

Sample crash report:
INFO: task syz.0.22:4510 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.22        state:D stack:0     pid:4510  ppid:4445   flags:0x00000001
Call trace:
 __switch_to+0x2f4/0x550 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5245 [inline]
 __schedule+0xdd0/0x1b0c kernel/sched/core.c:6562
 schedule+0xc4/0x170 kernel/sched/core.c:6638
 schedule_timeout+0xc8/0x2f4 kernel/time/timer.c:2144
 do_wait_for_common+0x288/0x3f8 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+0x44/0x5c kernel/sched/completion.c:138
 kthread_stop+0x1d0/0x7f8 kernel/kthread.c:711
 f2fs_stop_gc_thread+0x70/0xc0 fs/f2fs/gc.c:209
 f2fs_ioc_shutdown fs/f2fs/file.c:2361 [inline]
 __f2fs_ioctl+0x78b4/0xb194 fs/f2fs/file.c:4373
 f2fs_ioctl+0x130/0x1a0 fs/f2fs/file.c:4454
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffff8000153d7c30 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffff8000153d8450 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffff8000153d72c0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:349
2 locks held by getty/4080:
 #0: ffff0000d63e3098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff8000208fb2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x2ec/0xfa0 drivers/tty/n_tty.c:2198
3 locks held by kworker/0:4/4403:
 #0: ffff0000c0020938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x6b8/0x13a4 kernel/workqueue.c:2265
 #1: ffff800021057c20 ((work_completion)(&data->fib_event_work)){+.+.}-{0:0}, at: process_one_work+0x6fc/0x13a4 kernel/workqueue.c:2267
 #2: ffff0000eee93240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x1d0/0x27cc drivers/net/netdevsim/fib.c:1491
2 locks held by syz.8.105/5143:
 #0: ffff0000c0591ba8 (&bdev->bd_fsfreeze_mutex){+.+.}-{3:3}, at: freeze_bdev+0x34/0x1e8 block/bdev.c:260
 #1: ffff00010255e460 (sb_writers#12){+.+.}-{0:0}, at: sb_wait_write fs/super.c:1669 [inline]
 #1: ffff00010255e460 (sb_writers#12){+.+.}-{0:0}, at: freeze_super+0xec/0x360 fs/super.c:1760

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Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/04 08:12 linux-6.1.y cd9b81672742 42b01fab .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-1-kasan-arm64 INFO: task hung in f2fs_stop_gc_thread
2025/12/13 07:43 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in f2fs_stop_gc_thread
2026/02/04 05:21 linux-6.1.y cd9b81672742 42b01fab .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in f2fs_stop_gc_thread
* Struck through repros no longer work on HEAD.