Re: [syzbot] [ntfs3?] INFO: task hung in __start_renaming

syzbot
2025-11-24T07:13:04Z

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
INFO: task hung in __start_renaming

INFO: task syz.0.17:6473 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:27936 pid:6473 tgid:6471 ppid:6352 task_flags:0x400040 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5257 [inline]
__schedule+0x14bc/0x5030 kernel/sched/core.c:6864
__schedule_loop kernel/sched/core.c:6946 [inline]
schedule+0x165/0x360 kernel/sched/core.c:6961
schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7018
rwsem_down_write_slowpath+0x872/0xfe0 kernel/locking/rwsem.c:1185
__down_write_common kernel/locking/rwsem.c:1317 [inline]
__down_write kernel/locking/rwsem.c:1326 [inline]
down_write_nested+0x1b5/0x200 kernel/locking/rwsem.c:1707
inode_lock_nested include/linux/fs.h:1072 [inline]
lock_rename fs/namei.c:3681 [inline]
__start_renaming+0x148/0x410 fs/namei.c:3777
do_renameat2+0x399/0x8e0 fs/namei.c:5991
__do_sys_rename fs/namei.c:6059 [inline]
__se_sys_rename fs/namei.c:6057 [inline]
__x64_sys_rename+0x82/0x90 fs/namei.c:6057
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2425d8f749
RSP: 002b:00007f2426c44038 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 00007f2425fe6090 RCX: 00007f2425d8f749
RDX: 0000000000000000 RSI: 0000200000000080 RDI: 0000200000000340
RBP: 00007f2425e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2425fe6128 R14: 00007f2425fe6090 R15: 00007ffcd5a91138
</TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8df3d980 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8df3d980 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
#0: ffffffff8df3d980 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5592:
#0: ffff8880342450a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000332b2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
3 locks held by syz.0.17/6472:
2 locks held by syz.0.17/6473:
#0: ffff88805c19c420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:509
#1: ffff88805e78e988 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff88805e78e988 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: lock_rename fs/namei.c:3681 [inline]
#1: ffff88805e78e988 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_renaming+0x148/0x410 fs/namei.c:3777
3 locks held by syz.1.18/6495:
2 locks held by syz.1.18/6496:
#0: ffff88807bbb8420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:509
#1: ffff888073ef5af8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff888073ef5af8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: lock_rename fs/namei.c:3681 [inline]
#1: ffff888073ef5af8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_renaming+0x148/0x410 fs/namei.c:3777
5 locks held by syz.2.19/6519:
2 locks held by syz.2.19/6520:
#0: ffff888031634420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:509
#1: ffff888073e770d0 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff888073e770d0 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: lock_rename fs/namei.c:3681 [inline]
#1: ffff888073e770d0 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_renaming+0x148/0x410 fs/namei.c:3777
3 locks held by syz.3.20/6552:
2 locks held by syz.3.20/6553:
#0: ffff8880241de420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:509
#1: ffff888073ee5af8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff888073ee5af8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: lock_rename fs/namei.c:3681 [inline]
#1: ffff888073ee5af8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_renaming+0x148/0x410 fs/namei.c:3777
3 locks held by syz.4.21/6582:
2 locks held by syz.4.21/6583:
#0: ffff88805dafe420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:509
#1: ffff88805e78b690 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff88805e78b690 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: lock_rename fs/namei.c:3681 [inline]
#1: ffff88805e78b690 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_renaming+0x148/0x410 fs/namei.c:3777
3 locks held by syz.5.22/6613:
2 locks held by syz.5.22/6614:
#0: ffff88806d820420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:509
#1: ffff88805e7dcc68 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff88805e7dcc68 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: lock_rename fs/namei.c:3681 [inline]
#1: ffff88805e7dcc68 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_renaming+0x148/0x410 fs/namei.c:3777
3 locks held by syz.6.23/6654:
2 locks held by syz.6.23/6655:
#0: ffff888032cd2420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:509
#1: ffff88805e78f818 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff88805e78f818 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: lock_rename fs/namei.c:3681 [inline]
#1: ffff88805e78f818 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_renaming+0x148/0x410 fs/namei.c:3777
3 locks held by syz.7.24/6689:
2 locks held by syz.7.24/6690:
#0: ffff88807eda2420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:509
#1: ffff888073e73dd8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:1072 [inline]
#1: ffff888073e73dd8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: lock_rename fs/namei.c:3681 [inline]
#1: ffff888073e73dd8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: __start_renaming+0x148/0x410 fs/namei.c:3777

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [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:346 [inline]
watchdog+0xfb5/0x1000 kernel/hung_task.c:515
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6582 Comm: syz.4.21 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:246 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x11/0x90 kernel/kcov.c:314
Code: 09 cc 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 65 48 8b 14 25 08 60 76 92 <65> 8b 0d 68 82 b4 10 81 e1 00 01 ff 00 74 11 81 f9 00 01 00 00 75
RSP: 0018:ffffc900040bf660 EFLAGS: 00000246
RAX: ffffffff82417239 RBX: ffff888073e75268 RCX: df51652e15ac6b00
RDX: ffff888024430000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000817ec0 R12: ffff888073e75268
R13: ffff888073e752e8 R14: dffffc0000000000 R15: 0000000000000003
FS: 00007f2cd1b696c0(0000) GS:ffff888125fba000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055b091e56a38 CR3: 000000003082e000 CR4: 00000000003526f0
Call Trace:
<TASK>
inode_state_read+0x59/0xd0 include/linux/fs.h:888
insert_inode_locked+0x2c8/0x650 fs/inode.c:1873
ntfs_new_inode+0xc8/0x100 fs/ntfs3/fsntfs.c:1675
ntfs_create_inode+0x606/0x32a0 fs/ntfs3/inode.c:1309
ntfs_create+0x3d/0x50 fs/ntfs3/namei.c:110
lookup_open fs/namei.c:4409 [inline]
open_last_lookups fs/namei.c:4509 [inline]
path_openat+0x190f/0x3d90 fs/namei.c:4753
do_filp_open+0x1fa/0x410 fs/namei.c:4783
do_sys_openat2+0x121/0x1c0 fs/open.c:1432
do_sys_open fs/open.c:1447 [inline]
__do_sys_openat fs/open.c:1463 [inline]
__se_sys_openat fs/open.c:1458 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1458
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2cd0d8f749
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:00007f2cd1b69038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f2cd0fe5fa0 RCX: 00007f2cd0d8f749
RDX: 000000000000275a RSI: 00002000000001c0 RDI: ffffffffffffff9c
RBP: 00007f2cd0e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2cd0fe6038 R14: 00007f2cd0fe5fa0 R15: 00007ffce05c0bc8
</TASK>

Tested on:

commit: d724c6f8 Add linux-next specific files for 20251121
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17ce797c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=68d11c703cf8e4a0
dashboard link: https://syzkaller.appspot.com/bug?extid=2fefb910d2c20c0698d8
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=10fdf658580000