syzbot


INFO: task hung in queue_log_writer

Status: upstream: reported on 2025/12/17 19:23
Reported-by: syzbot+28a7d93d7179659c8737@syzkaller.appspotmail.com
First crash: 25d, last: 25d
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in queue_log_writer exfat 1 C inconclusive inconclusive 110 958d 1094d 0/29 auto-obsoleted due to no activity on 2023/12/25 14:05
linux-4.19 INFO: task hung in queue_log_writer reiserfs fat 1 C 8 1070d 1099d 0/1 upstream: reported C repro on 2023/01/08 18:46
linux-4.14 INFO: task hung in queue_log_writer reiserfs 1 1 1070d 1070d 0/1 upstream: reported on 2023/02/06 08:12

Sample crash report:
INFO: task kworker/0:0:8 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:0     state:D stack:22960 pid:8     ppid:2      flags:0x00004000
Workqueue: events_long flush_old_commits
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 queue_log_writer+0x1e8/0x2b0 fs/reiserfs/journal.c:2987
 check_journal_end fs/reiserfs/journal.c:3681 [inline]
 do_journal_end+0xa37/0x4860 fs/reiserfs/journal.c:4047
 reiserfs_sync_fs fs/reiserfs/super.c:78 [inline]
 flush_old_commits+0x213/0x2f0 fs/reiserfs/super.c:111
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
INFO: task kworker/0:5:5852 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:5     state:D stack:21656 pid:5852  ppid:2      flags:0x00004000
Workqueue: reiserfs/loop1 flush_async_commits
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
 reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
 flush_async_commits+0x46/0xc0 fs/reiserfs/journal.c:3554
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
INFO: task syz.2.216:6951 blocked for more than 145 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.216       state:D
 stack:26000 pid:6951  ppid:5768   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
 reiserfs_write_lock_nested+0x60/0xd0 fs/reiserfs/lock.c:78
 flush_commit_list+0x1253/0x1d80 fs/reiserfs/journal.c:1116
 flush_older_commits fs/reiserfs/journal.c:919 [inline]
 flush_commit_list+0x436/0x1d80 fs/reiserfs/journal.c:997
 do_journal_end+0x3c8c/0x4860 fs/reiserfs/journal.c:4379
 reiserfs_sync_fs+0xd0/0x150 fs/reiserfs/super.c:78
 iterate_supers+0xb2/0x170 fs/super.c:979
 ksys_sync+0xa4/0x150 fs/sync.c:103
 __ia32_sys_sync+0xe/0x20 fs/sync.c:113
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f442158f749
RSP: 002b:00007f4422387038 EFLAGS: 00000246
 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f44217e6090 RCX: 00007f442158f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f44217e6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f44217e6128 R14: 00007f44217e6090 R15: 00007ffe40435858
 </TASK>

Showing all locks held in the system:
1 lock held by pool_workqueue_/3:
 #0: ffffffff8cd358f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:324 [inline]
 #0: ffffffff8cd358f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x360/0x830 kernel/rcu/tree_exp.h:1004
3 locks held by kworker/0:0/8:
 #0: ffff888017871138 ((wq_completion)events_long){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017871138 ((wq_completion)events_long){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc900000d7d00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc900000d7d00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff888056ddc0e0 (&type->s_umount_key#25){++++}-{3:3}, at: flush_old_commits+0xcc/0x2f0 fs/reiserfs/super.c:97
1 lock held by khungtaskd/29:
 #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
3 locks held by kworker/u4:12/3549:
 #0: ffff888019e67938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888019e67938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc9000d397d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc9000d397d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff888056ddc0e0 (&type->s_umount_key#25){++++}-{3:3}, at: super_trylock_shared+0x20/0xf0 fs/super.c:607
2 locks held by getty/5536:
 #0: ffff888030b0a0a0 (&tty->ldisc_sem){++++}-{0:0}
, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: 
ffffc9000328b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
3 locks held by kworker/0:5/5852:
 #0: ffff888053c52138 ((wq_completion)reiserfs/loop1
){+.+.}-{0:0}
, at: process_one_work kernel/workqueue.c:2609 [inline]
, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc900049dfd00 ((work_completion)(&(&journal->j_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc900049dfd00 ((work_completion)(&(&journal->j_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff888024c49090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
9 locks held by syz.1.85/6188:
3 locks held by syz.2.216/6951:
 #0: ffff888056ddc0e0 (&type->s_umount_key#25){++++}-{3:3}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff888056ddc0e0 (&type->s_umount_key#25){++++}-{3:3}, at: super_lock+0x167/0x360 fs/super.c:117
 #1: ffff88802dc3c090 (&jl->j_commit_mutex){+.+.}-{3:3}, at: reiserfs_mutex_lock_safe fs/reiserfs/reiserfs.h:813 [inline]
 #1: ffff88802dc3c090 (&jl->j_commit_mutex){+.+.}-{3:3}, at: flush_commit_list+0x6c8/0x1d80 fs/reiserfs/journal.c:1007
 #2: ffff888024c49090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock_nested+0x60/0xd0 fs/reiserfs/lock.c:78
2 locks held by kworker/0:8/7828:
 #0: ffff888017872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017872538 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc90004dafd00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90004dafd00 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
2 locks held by syz-executor/8067:
 #0: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8dfb5448 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x76f/0xf10 net/core/rtnetlink.c:6469
 #1: ffffffff8cd358f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:324 [inline]
 #1: ffffffff8cd358f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x360/0x830 kernel/rcu/tree_exp.h:1004

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/17 19:23 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in queue_log_writer
* Struck through repros no longer work on HEAD.