syzbot

============================================
WARNING: possible recursive locking detected
syzkaller #0 Not tainted
--------------------------------------------
syz.2.19/6100 is trying to acquire lock:
ffff8880411488b0 (&ni->ni_lock#2/5){+.+.}-{4:4}, at: ni_lock fs/ntfs3/ntfs_fs.h:1113 [inline]
ffff8880411488b0 (&ni->ni_lock#2/5){+.+.}-{4:4}, at: mi_read+0x2d4/0x5a0 fs/ntfs3/record.c:148

but task is already holding lock:
ffff88804114bef0 (&ni->ni_lock#2/5){+.+.}-{4:4}, at: ni_lock fs/ntfs3/ntfs_fs.h:1113 [inline]
ffff88804114bef0 (&ni->ni_lock#2/5){+.+.}-{4:4}, at: ntfs_link+0xf6/0x280 fs/ntfs3/namei.c:141

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&ni->ni_lock#2/5);
  lock(&ni->ni_lock#2/5);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

6 locks held by syz.2.19/6100:
 #0: ffff888026f52488 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:557
 #1: ffff88804114b9e8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: inode_lock_nested include/linux/fs.h:915 [inline]
 #1: ffff88804114b9e8 (&type->i_mutex_dir_key#8/1){+.+.}-{4:4}, at: filename_create+0x1f8/0x3c0 fs/namei.c:4139
 #2: ffff88804114c1a8 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:870 [inline]
 #2: ffff88804114c1a8 (&sb->s_type->i_mutex_key#20){+.+.}-{4:4}, at: vfs_link+0x3b4/0x6e0 fs/namei.c:4845
 #3: ffff88804114b730 (&ni->ni_lock#2/6){+.+.}-{4:4}, at: ni_lock_dir fs/ntfs3/ntfs_fs.h:1118 [inline]
 #3: ffff88804114b730 (&ni->ni_lock#2/6){+.+.}-{4:4}, at: ntfs_link+0xdb/0x280 fs/ntfs3/namei.c:139
 #4: ffff88804114bef0 (&ni->ni_lock#2/5){+.+.}-{4:4}, at: ni_lock fs/ntfs3/ntfs_fs.h:1113 [inline]
 #4: ffff88804114bef0 (&ni->ni_lock#2/5){+.+.}-{4:4}, at: ntfs_link+0xf6/0x280 fs/ntfs3/namei.c:141
 #5: ffff88802695c118 (&wnd->rw_lock/1){+.+.}-{4:4}, at: ntfs_look_free_mft+0x163/0xd50 fs/ntfs3/fsntfs.c:571

stack backtrace:
CPU: 0 UID: 0 PID: 6100 Comm: syz.2.19 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3895
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/rtmutex_api.c:535 [inline]
 mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:547
 ni_lock fs/ntfs3/ntfs_fs.h:1113 [inline]
 mi_read+0x2d4/0x5a0 fs/ntfs3/record.c:148
 mi_format_new+0x1a3/0x610 fs/ntfs3/record.c:434
 ni_add_subrecord+0xd0/0x440 fs/ntfs3/frecord.c:321
 ntfs_look_free_mft+0x6aa/0xd50 fs/ntfs3/fsntfs.c:715
 ni_create_attr_list+0x8ff/0x13d0 fs/ntfs3/frecord.c:826
 ni_ins_attr_ext+0x43e/0xb50 fs/ntfs3/frecord.c:924
 ni_insert_attr fs/ntfs3/frecord.c:1091 [inline]
 ni_insert_resident fs/ntfs3/frecord.c:1475 [inline]
 ni_add_name+0x6df/0xc90 fs/ntfs3/frecord.c:2987
 ntfs_link_inode+0x132/0x180 fs/ntfs3/inode.c:1728
 ntfs_link+0x118/0x280 fs/ntfs3/namei.c:146
 vfs_link+0x4ea/0x6e0 fs/namei.c:4854
 do_linkat+0x272/0x560 fs/namei.c:4924
 __do_sys_linkat fs/namei.c:4952 [inline]
 __se_sys_linkat fs/namei.c:4949 [inline]
 __x64_sys_linkat+0xd4/0xf0 fs/namei.c:4949
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7e89c5eba9
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:00007f7e892a5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000109
RAX: ffffffffffffffda RBX: 00007f7e89ea6090 RCX: 00007f7e89c5eba9
RDX: 0000000000000005 RSI: 0000200000000300 RDI: 0000000000000005
RBP: 00007f7e89ce1e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000400 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7e89ea6128 R14: 00007f7e89ea6090 R15: 00007ffe9156bc98
 </TASK>