syzbot


INFO: task hung in reiserfs_file_release

Status: upstream: reported C repro on 2025/12/18 08:04
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+580622a45a8996907000@syzkaller.appspotmail.com
First crash: 9d01h, last: 9d01h
Bug presence (2)
Date Name Commit Repro Result
2025/12/19 linux-6.6.y (ToT) 5fa4793a2d2d C [report] INFO: task hung in flush_old_commits
2025/12/19 upstream (ToT) dd9b004b7ff3 C Didn't crash
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: task hung in reiserfs_file_release 1 2 432d 432d 0/3 auto-obsoleted due to no activity on 2025/01/29 07:17

Sample crash report:
INFO: task syz.0.17:5955 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:25544 pid:5955  ppid:5905   flags:0x00004004
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
 reiserfs_file_release+0x452/0xa50 fs/reiserfs/file.c:53
 __fput+0x234/0x970 fs/file_table.c:384
 task_work_run+0x1ce/0x250 kernel/task_work.c:239
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff19538f749
RSP: 002b:00007ffceb2e94d8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ff1955e7da0 RCX: 00007ff19538f749
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007ff1955e7da0 R08: 0000000000000000 R09: 00000005eb2e97cf
R10: 00007ff1955e7cb0 R11: 0000000000000246 R12: 000000000002ef82
R13: 00007ffceb2e95d0 R14: ffffffffffffffff R15: 00007ffceb2e95f0
 </TASK>

Showing all locks held in the system:
4 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: ffff88802e0f60e0 (&type->s_umount_key#26){++++}-{3:3}, at: flush_old_commits+0xcc/0x2f0 fs/reiserfs/super.c:97
 #3: ffff888144b37090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
2 locks held by kworker/u4:0/11:
 #0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffff8880b8e289c0 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:189 [inline]
 #1: ffff8880b8e289c0 (psi_seq){-.-.}-{0:0}, at: __schedule+0x20ee/0x44d0 kernel/sched/core.c:6694
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
4 locks held by kworker/0:2/787:
 #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: ffffc90003887d00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90003887d00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff88802e0080e0 (&type->s_umount_key#26){++++}-{3:3}, at: flush_old_commits+0xcc/0x2f0 fs/reiserfs/super.c:97
 #3: ffff88802ee4c090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
2 locks held by kworker/u4:6/1118:
 #0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #0: ffff888017871538 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #1: ffffc9000478fd00 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc9000478fd00 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
3 locks held by kworker/u4:9/1144:
4 locks held by kworker/1:2/1191:
 #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: ffffc90004a1fd00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90004a1fd00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff88805bf160e0 (&type->s_umount_key#26){++++}-{3:3}, at: flush_old_commits+0xcc/0x2f0 fs/reiserfs/super.c:97
 #3: ffff88805bf19090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
3 locks held by kworker/u4:10/3463:
2 locks held by getty/5526:
 #0: ffff88802cf9b0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000326e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x425/0x1380 drivers/tty/n_tty.c:2217
4 locks held by kworker/0:3/5831:
 #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: ffffc900047bfd00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc900047bfd00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff888021d7a0e0 (&type->s_umount_key#26){++++}-{3:3}, at: flush_old_commits+0xcc/0x2f0 fs/reiserfs/super.c:97
 #3: ffff88814c8b3090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
4 locks held by kworker/1:4/5896:
 #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: ffffc90003207d00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90003207d00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff88802382e0e0 (&type->s_umount_key#26){++++}-{3:3}, at: flush_old_commits+0xcc/0x2f0 fs/reiserfs/super.c:97
 #3: ffff88807eb9d090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
4 locks held by kworker/0:4/5897:
 #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: ffffc900032f7d00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc900032f7d00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff888071a620e0 (&type->s_umount_key#26){++++}-{3:3}, at: flush_old_commits+0xcc/0x2f0 fs/reiserfs/super.c:97
 #3: ffff88801bb7b090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
2 locks held by syz.0.17/5955:
 #0: ffff88805e1c80b8 (&ei->tailpack){+.+.}-{3:3}, at: reiserfs_file_release+0xc3/0xa50 fs/reiserfs/file.c:41
 #1: ffff888144b37090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
3 locks held by syz.0.17/5956:
2 locks held by syz.1.18/5979:
 #0: ffff88805e189498 (&ei->tailpack){+.+.}-{3:3}, at: reiserfs_file_release+0xc3/0xa50 fs/reiserfs/file.c:41
 #1: ffff88807eb9d090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
3 locks held by syz.1.18/5980:
2 locks held by syz.2.19/6003:
 #0: ffff88805e1c9b38 (&ei->tailpack){+.+.}-{3:3}, at: reiserfs_file_release+0xc3/0xa50 fs/reiserfs/file.c:41
 #1: ffff88814c8b3090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
3 locks held by syz.2.19/6004:
2 locks held by syz.3.20/6035:
 #0: ffff88805e1caf18 (&ei->tailpack){+.+.}-{3:3}, at: reiserfs_file_release+0xc3/0xa50 fs/reiserfs/file.c:41
 #1: ffff88802ee4c090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
3 locks held by syz.3.20/6038:
2 locks held by syz.4.21/6068:
 #0: ffff88805e189b38 (&ei->tailpack){+.+.}-{3:3}, at: reiserfs_file_release+0xc3/0xa50 fs/reiserfs/file.c:41
 #1: ffff88805bf19090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
3 locks held by syz.4.21/6071:
4 locks held by kworker/1:5/6089:
 #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: ffffc90003b17d00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2609 [inline]
 #1: ffffc90003b17d00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x957/0x15b0 kernel/workqueue.c:2711
 #2: ffff8880600b40e0 (&type->s_umount_key#26){++++}-{3:3}, at: flush_old_commits+0xcc/0x2f0 fs/reiserfs/super.c:97
 #3: ffff88802938e090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
2 locks held by syz.5.22/6101:
 #0: ffff88805e18af18 (&ei->tailpack){+.+.}-{3:3}, at: reiserfs_file_release+0xc3/0xa50 fs/reiserfs/file.c:41
 #1: ffff88802938e090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
3 locks held by syz.5.22/6104:
2 locks held by syz.6.23/6140:
 #0: ffff88805e1cc2f8 (&ei->tailpack){+.+.}-{3:3}, at: reiserfs_file_release+0xc3/0xa50 fs/reiserfs/file.c:41
 #1: ffff88801bb7b090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0xd0 fs/reiserfs/lock.c:27
3 locks held by syz.6.23/6143:
2 locks held by syz-executor/6146:

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

NMI backtrace for cpu 0
CPU: 0 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x39b/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf41/0xf80 kernel/hung_task.c:379
 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>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 6004 Comm: syz.2.19 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:get_num_ver+0x4f0/0xfe0 fs/reiserfs/fix_node.c:499
Code: 35 63 ff 45 39 f5 7e 65 89 df 44 89 f6 e8 18 35 63 ff 44 39 f3 0f 9e c3 31 ff 44 8b 74 24 40 44 89 f6 e8 33 37 63 ff 45 85 f6 <0f> 94 c0 20 d8 3c 01 0f 85 91 00 00 00 e8 6e 33 63 ff 48 8b 44 24
RSP: 0018:ffffc90003666a40 EFLAGS: 00000202
RAX: ffffffff82225d3d RBX: 0000000000001000 RCX: 0000000000000000
RDX: ffff88802cfe1e00 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc90003666b80 R08: 0000000000000000 R09: 00000000ffffffff
R10: 00000000ffffffff R11: 0000000000000000 R12: ffff88807c4bc080
R13: 0000000000001018 R14: 0000000000000001 R15: 1ffff1100f897810
FS:  00007f2176d626c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f3ad2ae4e9c CR3: 000000002d7dd000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 ip_check_balance fs/reiserfs/fix_node.c:1523 [inline]
 check_balance fs/reiserfs/fix_node.c:2083 [inline]
 fix_nodes+0x2854/0x82e0 fs/reiserfs/fix_node.c:2636
 reiserfs_paste_into_item+0x5ce/0x7f0 fs/reiserfs/stree.c:2128
 reiserfs_get_block+0x1bd3/0x3ed0 fs/reiserfs/inode.c:1069
 __block_write_begin_int+0x566/0x1ad0 fs/buffer.c:2124
 reiserfs_write_begin+0x20a/0x4c0 fs/reiserfs/inode.c:2771
 generic_cont_expand_simple+0x13a/0x200 fs/buffer.c:2482
 reiserfs_setattr+0x58f/0x11a0 fs/reiserfs/inode.c:3302
 notify_change+0xb0d/0xe10 fs/attr.c:499
 do_truncate+0x19b/0x220 fs/open.c:66
 vfs_truncate+0x266/0x300 fs/open.c:112
 do_sys_truncate+0xe0/0x1a0 fs/open.c:135
 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: 0033:0x7f2175f8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2176d62038 EFLAGS: 00000246 ORIG_RAX: 000000000000004c
RAX: ffffffffffffffda RBX: 00007f21761e5fa0 RCX: 00007f2175f8f749
RDX: 0000000000000000 RSI: 000000000800088a RDI: 0000200000000000
RBP: 00007f2176013f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f21761e6038 R14: 00007f21761e5fa0 R15: 00007ffe32f88518
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/18 08:04 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-6-6-kasan INFO: task hung in reiserfs_file_release
* Struck through repros no longer work on HEAD.