Kernel bug: possible deadlock in ntfs_look_for_free_space
Subsystem: ntfs3
Status: open

Crash report:
======================================================
WARNING: possible circular locking dependency detected
6.16.0-syzkaller-06699-ge8d780dcd957 #0 Tainted: G        W          
------------------------------------------------------
syz-executor103/5895 is trying to acquire lock:
ffff888044bfa250 (&wnd->rw_lock){++++}-{4:4}, at: ntfs_look_for_free_space+0xd3/0x600 fs/ntfs3/fsntfs.c:362

but task is already holding lock:
ffff8880416f75d0 (&ni->file.run_lock#2){++++}-{4:4}, at: ntfs_extend_mft+0x13d/0x450 fs/ntfs3/fsntfs.c:511

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ni->file.run_lock#2){++++}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       down_read+0x97/0x1f0 kernel/locking/rwsem.c:1522
       run_unpack_ex+0x7e5/0xba0 fs/ntfs3/run.c:1119
       ntfs_read_mft fs/ntfs3/inode.c:401 [inline]
       ntfs_iget5+0x232b/0x37c0 fs/ntfs3/inode.c:540
       dir_search_u+0x1df/0x2c0 fs/ntfs3/dir.c:264
       ntfs_lookup+0xfb/0x1f0 fs/ntfs3/namei.c:85
       lookup_one_qstr_excl+0x131/0x360 fs/namei.c:1697
       do_unlinkat+0x1df/0x570 fs/namei.c:4638
       __do_sys_unlink fs/namei.c:4696 [inline]
       __se_sys_unlink fs/namei.c:4694 [inline]
       __x64_sys_unlink+0x47/0x50 fs/namei.c:4694
       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

-> #0 (&wnd->rw_lock){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       down_write_nested+0x3e/0x60 kernel/locking/rwsem.c:1691
       ntfs_look_for_free_space+0xd3/0x600 fs/ntfs3/fsntfs.c:362
       attr_allocate_clusters+0x1c1/0x6d0 fs/ntfs3/attrib.c:159
       attr_set_size+0x14a4/0x2c70 fs/ntfs3/attrib.c:574
       ntfs_extend_mft+0x162/0x450 fs/ntfs3/fsntfs.c:512
       ntfs_look_free_mft+0x5f8/0xd50 fs/ntfs3/fsntfs.c:709
       ntfs_create_inode+0x590/0x32a0 fs/ntfs3/inode.c:1296
       ntfs_create+0x3d/0x50 fs/ntfs3/namei.c:110
       lookup_open fs/namei.c:3708 [inline]
       open_last_lookups fs/namei.c:3807 [inline]
       path_openat+0x1500/0x3840 fs/namei.c:4043
       do_filp_open+0x1fa/0x410 fs/namei.c:4073
       do_sys_openat2+0x121/0x1c0 fs/open.c:1435
       do_sys_open fs/open.c:1450 [inline]
       __do_sys_open fs/open.c:1458 [inline]
       __se_sys_open fs/open.c:1454 [inline]
       __x64_sys_open+0x11e/0x150 fs/open.c:1454
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ni->file.run_lock#2);
                               lock(&wnd->rw_lock);
                               lock(&ni->file.run_lock#2);
  lock(&wnd->rw_lock);

 *** DEADLOCK ***

5 locks held by syz-executor103/5895:
 #0: ffff888044bf8488 (sb_writers#8){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:557
 #1: ffff8880415f9ae8 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: inode_lock include/linux/fs.h:869 [inline]
 #1: ffff8880415f9ae8 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: open_last_lookups fs/namei.c:3804 [inline]
 #1: ffff8880415f9ae8 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: path_openat+0x8e6/0x3840 fs/namei.c:4043
 #2: ffff8880415f9830 (&ni->ni_lock#2/6){+.+.}-{4:4}, at: ni_lock_dir fs/ntfs3/ntfs_fs.h:1118 [inline]
 #2: ffff8880415f9830 (&ni->ni_lock#2/6){+.+.}-{4:4}, at: ntfs_create_inode+0x16e/0x32a0 fs/ntfs3/inode.c:1204
 #3: ffff888044bfa118 (&wnd->rw_lock/1){+.+.}-{4:4}, at: ntfs_look_free_mft+0x163/0xd50 fs/ntfs3/fsntfs.c:571
 #4: ffff8880416f75d0 (&ni->file.run_lock#2){++++}-{4:4}, at: ntfs_extend_mft+0x13d/0x450 fs/ntfs3/fsntfs.c:511

stack backtrace:
CPU: 0 UID: 0 PID: 5895 Comm: syz-executor103 Tainted: G        W           6.16.0-syzkaller-06699-ge8d780dcd957 #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 down_write_nested+0x3e/0x60 kernel/locking/rwsem.c:1691
 ntfs_look_for_free_space+0xd3/0x600 fs/ntfs3/fsntfs.c:362
 attr_allocate_clusters+0x1c1/0x6d0 fs/ntfs3/attrib.c:159
 attr_set_size+0x14a4/0x2c70 fs/ntfs3/attrib.c:574
 ntfs_extend_mft+0x162/0x450 fs/ntfs3/fsntfs.c:512
 ntfs_look_free_mft+0x5f8/0xd50 fs/ntfs3/fsntfs.c:709
 ntfs_create_inode+0x590/0x32a0 fs/ntfs3/inode.c:1296
 ntfs_create+0x3d/0x50 fs/ntfs3/namei.c:110
 lookup_open fs/namei.c:3708 [inline]
 open_last_lookups fs/namei.c:3807 [inline]
 path_openat+0x1500/0x3840 fs/namei.c:4043
 do_filp_open+0x1fa/0x410 fs/namei.c:4073
 do_sys_openat2+0x121/0x1c0 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_open fs/open.c:1458 [inline]
 __se_sys_open fs/open.c:1454 [inline]
 __x64_sys_open+0x11e/0x150 fs/open.c:1454
 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: 0033:0x7fde85023499
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 18 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc366140f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000200000000640 RCX: 00007fde85023499
RDX: 0000000000000000 RSI: 000000000014d27c RDI: 0000200000000180
RBP: 000020000001f840 R08: 002c6174656d776f R09: 00007ffc36614130
R10: 00007ffc36613fc0 R11: 0000000000000246 R12: 00007ffc3661411c
R13: 000000000000000c R14: 431bde82d7b634db R15: 00007ffc36614150
 </TASK>
ntfs3(loop0): ino=0, attr_set_size