syzbot

loop3: detected capacity change from 0 to 4096
======================================================
WARNING: possible circular locking dependency detected
6.6.102-syzkaller #0 Not tainted
------------------------------------------------------
syz.3.1593/10955 is trying to acquire lock:
ffff88807db56a20 (&mm->mmap_lock){++++}-{3:3}, at: __might_fault+0xaa/0x120 mm/memory.c:5946

but task is already holding lock:
ffff888059776840 (&ni->ni_lock#2/5){+.+.}-{3:3}, at: ni_lock fs/ntfs3/ntfs_fs.h:1119 [inline]
ffff888059776840 (&ni->ni_lock#2/5){+.+.}-{3:3}, at: ntfs_fiemap+0xc8/0x130 fs/ntfs3/file.c:1214

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ni->ni_lock#2/5){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
       ni_lock fs/ntfs3/ntfs_fs.h:1119 [inline]
       attr_data_get_block+0x2ed/0x1eb0 fs/ntfs3/attrib.c:918
       ntfs_file_mmap+0x4c0/0x760 fs/ntfs3/file.c:294
       call_mmap include/linux/fs.h:2023 [inline]
       mmap_file mm/internal.h:98 [inline]
       __mmap_region mm/mmap.c:2786 [inline]
       mmap_region+0xe57/0x1f80 mm/mmap.c:2937
       do_mmap+0x8d1/0xfd0 mm/mmap.c:1381
       vm_mmap_pgoff+0x1c0/0x400 mm/util.c:556
       ksys_mmap_pgoff+0x520/0x700 mm/mmap.c:1427
       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

-> #0 (&mm->mmap_lock){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
       lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
       __might_fault+0xc6/0x120 mm/memory.c:5946
       _copy_to_user+0x2a/0xa0 lib/usercopy.c:36
       copy_to_user include/linux/uaccess.h:191 [inline]
       fiemap_fill_next_extent+0x1c1/0x390 fs/ioctl.c:145
       ni_fiemap+0x89d/0xbe0 fs/ntfs3/frecord.c:2060
       ntfs_fiemap+0xdb/0x130 fs/ntfs3/file.c:1216
       ioctl_fiemap fs/ioctl.c:220 [inline]
       do_vfs_ioctl+0x140c/0x1bb0 fs/ioctl.c:811
       __do_sys_ioctl fs/ioctl.c:869 [inline]
       __se_sys_ioctl+0x83/0x170 fs/ioctl.c:857
       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

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ni->ni_lock#2/5);
                               lock(&mm->mmap_lock);
                               lock(&ni->ni_lock#2/5);
  rlock(&mm->mmap_lock);

 *** DEADLOCK ***

1 lock held by syz.3.1593/10955:
 #0: ffff888059776840 (&ni->ni_lock#2/5){+.+.}-{3:3}, at: ni_lock fs/ntfs3/ntfs_fs.h:1119 [inline]
 #0: ffff888059776840 (&ni->ni_lock#2/5){+.+.}-{3:3}, at: ntfs_fiemap+0xc8/0x130 fs/ntfs3/file.c:1214

stack backtrace:
CPU: 1 PID: 10955 Comm: syz.3.1593 Not tainted 6.6.102-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __might_fault+0xc6/0x120 mm/memory.c:5946
 _copy_to_user+0x2a/0xa0 lib/usercopy.c:36
 copy_to_user include/linux/uaccess.h:191 [inline]
 fiemap_fill_next_extent+0x1c1/0x390 fs/ioctl.c:145
 ni_fiemap+0x89d/0xbe0 fs/ntfs3/frecord.c:2060
 ntfs_fiemap+0xdb/0x130 fs/ntfs3/file.c:1216
 ioctl_fiemap fs/ioctl.c:220 [inline]
 do_vfs_ioctl+0x140c/0x1bb0 fs/ioctl.c:811
 __do_sys_ioctl fs/ioctl.c:869 [inline]
 __se_sys_ioctl+0x83/0x170 fs/ioctl.c:857
 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: 0033:0x7f4041d8ebe9
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:00007f403fff6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f4041fb5fa0 RCX: 00007f4041d8ebe9
RDX: 0000200000000340 RSI: 00000000c020660b RDI: 0000000000000005
RBP: 00007f4041e11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4041fb6038 R14: 00007f4041fb5fa0 R15: 00007ffe6bf99278
 </TASK>