[v5.15] INFO: task hung in reiserfs_lookup (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dc027a595035 Linux 5.15.209
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1117a0ae580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=7ecf4a692fbd70ddc2de
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/586ac2a2fd9d/disk-dc027a59.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/06dcb6a2fcd3/vmlinux-dc027a59.xz
kernel image: https://storage.googleapis.com/syzbot-assets/567131e0cbcc/bzImage-dc027a59.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7ecf4a...@syzkaller.appspotmail.com

INFO: task syz.4.108:4836 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.108 state:D stack:26672 pid: 4836 ppid: 4201 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
__mutex_lock_common+0xcfc/0x2400 kernel/locking/mutex.c:669
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
reiserfs_write_lock+0x75/0xd0 fs/reiserfs/lock.c:27
reiserfs_lookup+0x18a/0x480 fs/reiserfs/namei.c:364
lookup_open fs/namei.c:3448 [inline]
open_last_lookups fs/namei.c:3540 [inline]
path_openat+0x1022/0x2fa0 fs/namei.c:3747
do_filp_open+0x1e2/0x410 fs/namei.c:3777
do_sys_openat2+0x150/0x4b0 fs/open.c:1255
do_sys_open fs/open.c:1271 [inline]
__do_sys_openat fs/open.c:1287 [inline]
__se_sys_openat fs/open.c:1282 [inline]
__x64_sys_openat+0x135/0x160 fs/open.c:1282
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f8d48dfbe59
RSP: 002b:00007f8d47034028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f8d49075090 RCX: 00007f8d48dfbe59
RDX: 000000000000275a RSI: 0000200000000080 RDI: ffffffffffffff9c
RBP: 00007f8d48e91d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8d49075128 R14: 00007f8d49075090 R15: 00007ffda4b60ca8
</TASK>
INFO: task syz.4.108:4839 blocked for more than 144 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.108 state:D stack:27344 pid: 4839 ppid: 4201 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5049 [inline]
__schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
schedule+0x11b/0x1e0 kernel/sched/core.c:6478
rwsem_down_write_slowpath+0xc87/0x1260 kernel/locking/rwsem.c:1165
inode_lock include/linux/fs.h:787 [inline]
open_last_lookups fs/namei.c:3537 [inline]
path_openat+0x803/0x2fa0 fs/namei.c:3747
do_filp_open+0x1e2/0x410 fs/namei.c:3777
do_sys_openat2+0x150/0x4b0 fs/open.c:1255
do_sys_open fs/open.c:1271 [inline]
__do_sys_openat fs/open.c:1287 [inline]
__se_sys_openat fs/open.c:1282 [inline]
__x64_sys_openat+0x135/0x160 fs/open.c:1282
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f8d48dfbe59
RSP: 002b:00007f8d47013028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f8d49075180 RCX: 00007f8d48dfbe59
RDX: 000000000000275a RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007f8d48e91d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8d49075218 R14: 00007f8d49075180 R15: 00007ffda4b60ca8
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
#0: ffffffff8c31f360 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by getty/3955:
#0: ffff88802c317098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
#1: ffffc900025e62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5df/0x1a70 drivers/tty/n_tty.c:2158
4 locks held by kworker/0:7/4269:
#0: ffff888016c71138 ((wq_completion)events_long){+.+.}-{0:0}, at: process_one_work+0x761/0x1010 kernel/workqueue.c:-1
#1: ffffc900011efd00 ((work_completion)(&(&sbi->old_work)->work)){+.+.}-{0:0}, at: process_one_work+0x79f/0x1010 kernel/workqueue.c:2285
#2:
ffff88807960c0e0 (&type->s_umount_key#56){++++}-{3:3}, at: flush_old_commits+0xce/0x310 fs/reiserfs/super.c:97
#3: ffff88801ef50090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x75/0xd0 fs/reiserfs/lock.c:27
3 locks held by kworker/u4:6/4350:
3 locks held by kworker/1:9/4545:
#0:
ffff8880b913a358 (&rq->__lock){-.-.}-{2:2}
, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:475
#1: ffff8880b9127888 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x4fe/0x7d0 kernel/sched/psi.c:891
#2: ffff88805de0e240 (&data->fib_lock){+.+.}-{3:3}, at: nsim_fib_event_work+0x26a/0x33e0 drivers/net/netdevsim/fib.c:1480
2 locks held by syz.4.108/4806:
3 locks held by syz.4.108/4836:
#0: ffff88807960c460 (sb_writers#16){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
#1: ffff888073e296c0 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
#1: ffff888073e296c0 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: open_last_lookups fs/namei.c:3537 [inline]
#1: ffff888073e296c0 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: path_openat+0x803/0x2fa0 fs/namei.c:3747
#2: ffff88801ef50090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x75/0xd0 fs/reiserfs/lock.c:27
2 locks held by syz.4.108/4839:
#0: ffff88807960c460 (sb_writers#16){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:386
#1: ffff888073e296c0 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
#1: ffff888073e296c0 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: open_last_lookups fs/namei.c:3537 [inline]
#1: ffff888073e296c0 (&type->i_mutex_dir_key#10){++++}-{3:3}, at: path_openat+0x803/0x2fa0 fs/namei.c:3747
3 locks held by syz.8.411/7032:
1 lock held by dhcpcd-run-hook/7060:

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
watchdog+0xe0f/0xe50 kernel/hung_task.c:369
kthread+0x436/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4806 Comm: syz.4.108 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:io_serial_in+0x73/0xb0 drivers/tty/serial/8250/8250_port.c:461
Code: e8 52 4f 29 fd 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 93 68 6e fd 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 44 89 f9 80 e1 07 38 c1 7c aa 4c
RSP: 0018:ffffc9000134dd70 EFLAGS: 00000002
RAX: 1ffffffff2cc0b00 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 000000000007ffff RDI: 0000000000080000
RBP: 0000000000000020 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000269ba4 R12: dffffc0000000000
R13: 1ffffffff2c64330 R14: ffffffff966058a0 R15: 0000000000000000
FS: 00007f8d470556c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f684e86d7d0 CR3: 000000006336d000 CR4: 00000000003526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
serial_in drivers/tty/serial/8250/8250.h:116 [inline]
wait_for_xmitr+0x4c/0x260 drivers/tty/serial/8250/8250_port.c:2069
serial8250_console_putchar+0x1a/0x50 drivers/tty/serial/8250/8250_port.c:3315
uart_console_write+0xaa/0x100 drivers/tty/serial/serial_core.c:1981
serial8250_console_write+0xc46/0x1000 drivers/tty/serial/8250/8250_port.c:3392
call_console_drivers kernel/printk/printk.c:-1 [inline]
console_unlock+0xb9a/0x1120 kernel/printk/printk.c:2744
vprintk_emit+0xc0/0x150 kernel/printk/printk.c:2274
_printk+0xda/0x130 kernel/printk/printk.c:2299
__reiserfs_warning+0x16c/0x1b0 fs/reiserfs/prints.c:290
reiserfs_read_bitmap_block+0x216/0x680 fs/reiserfs/bitmap.c:1434
scan_bitmap_block+0x1a8/0xe20 fs/reiserfs/bitmap.c:164
scan_bitmap fs/reiserfs/bitmap.c:391 [inline]
allocate_without_wrapping_disk fs/reiserfs/bitmap.c:1161 [inline]
blocknrs_and_prealloc_arrays_from_search_start fs/reiserfs/bitmap.c:1274 [inline]
reiserfs_allocate_blocknrs+0x279c/0x4e80 fs/reiserfs/bitmap.c:1375
reiserfs_new_form_blocknrs fs/reiserfs/reiserfs.h:3341 [inline]
get_empty_nodes+0x42e/0x920 fs/reiserfs/fix_node.c:879
fix_nodes+0x1ebc/0x8340 fs/reiserfs/fix_node.c:2662
reiserfs_paste_into_item+0x60b/0x810 fs/reiserfs/stree.c:2130
reiserfs_get_block+0x1c3a/0x42a0 fs/reiserfs/inode.c:1077
__block_write_begin_int+0x565/0x15d0 fs/buffer.c:2012
reiserfs_write_begin+0x34b/0x810 fs/reiserfs/inode.c:2790
generic_perform_write+0x2b6/0x550 mm/filemap.c:3785
__generic_file_write_iter+0x25f/0x4e0 mm/filemap.c:3912
generic_file_write_iter+0xa6/0x1b0 mm/filemap.c:3944
call_write_iter include/linux/fs.h:2173 [inline]
aio_write+0x54a/0x780 fs/aio.c:1594
__io_submit_one fs/aio.c:-1 [inline]
io_submit_one+0x6cd/0x1380 fs/aio.c:2013
__do_sys_io_submit fs/aio.c:2072 [inline]
__se_sys_io_submit+0x19d/0x310 fs/aio.c:2042
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f8d48dfbe59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8d47055028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1
RAX: ffffffffffffffda RBX: 00007f8d49074fa0 RCX: 00007f8d48dfbe59
RDX: 0000200000000200 RSI: 0000000000000001 RDI: 00007f8d4904e000
RBP: 00007f8d48e91d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8d49075038 R14: 00007f8d49074fa0 R15: 00007ffda4b60ca8
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup