syzbot

loop0: detected capacity change from 0 to 4096
======================================================
WARNING: possible circular locking dependency detected
6.1.144-syzkaller #0 Not tainted
------------------------------------------------------
syz.0.16/4468 is trying to acquire lock:
ffff0000cd194348 (&mm->mmap_lock){++++}-{3:3}, at: __might_fault+0x9c/0x124 mm/memory.c:5851

but task is already holding lock:
ffff0000e9a4e840 (&ni->ni_lock/5){+.+.}-{3:3}, at: ni_lock fs/ntfs3/ntfs_fs.h:1102 [inline]
ffff0000e9a4e840 (&ni->ni_lock/5){+.+.}-{3:3}, at: ntfs_fiemap+0xd0/0x140 fs/ntfs3/file.c:1168

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ni->ni_lock/5){+.+.}-{3:3}:
       __mutex_lock_common+0x190/0x1f38 kernel/locking/mutex.c:603
       __mutex_lock kernel/locking/mutex.c:747 [inline]
       mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
       ni_lock fs/ntfs3/ntfs_fs.h:1102 [inline]
       attr_data_get_block+0x20c/0x1528 fs/ntfs3/attrib.c:951
       ntfs_file_mmap+0x368/0x55c fs/ntfs3/file.c:312
       call_mmap include/linux/fs.h:2270 [inline]
       mmap_file+0x6c/0xc8 mm/util.c:1109
       __mmap_region mm/mmap.c:2768 [inline]
       mmap_region+0xcc8/0x1860 mm/mmap.c:2912
       do_mmap+0x978/0x10dc mm/mmap.c:1432
       vm_mmap_pgoff+0x184/0x284 mm/util.c:520
       ksys_mmap_pgoff+0x3b8/0x5a0 mm/mmap.c:1478
       __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline]
       __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline]
       __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
       do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
       el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

-> #0 (&mm->mmap_lock){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x293c/0x6544 kernel/locking/lockdep.c:5049
       lock_acquire+0x20c/0x644 kernel/locking/lockdep.c:5662
       __might_fault+0xc4/0x124 mm/memory.c:5852
       _copy_to_user include/linux/uaccess.h:143 [inline]
       copy_to_user include/linux/uaccess.h:169 [inline]
       ni_fiemap+0x3fc/0x1030 fs/ntfs3/frecord.c:2140
       ntfs_fiemap+0xe4/0x140 fs/ntfs3/file.c:1170
       ioctl_fiemap fs/ioctl.c:219 [inline]
       do_vfs_ioctl+0x1694/0x206c fs/ioctl.c:810
       __do_sys_ioctl fs/ioctl.c:868 [inline]
       __se_sys_ioctl fs/ioctl.c:856 [inline]
       __arm64_sys_ioctl+0xe4/0x1c8 fs/ioctl.c:856
       __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
       invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
       el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
       do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
       el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
       el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
       el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

other info that might help us debug this:

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

1 lock held by syz.0.16/4468:
 #0: ffff0000e9a4e840 (&ni->ni_lock/5){+.+.}-{3:3}, at: ni_lock fs/ntfs3/ntfs_fs.h:1102 [inline]
 #0: ffff0000e9a4e840 (&ni->ni_lock/5){+.+.}-{3:3}, at: ntfs_fiemap+0xd0/0x140 fs/ntfs3/file.c:1168

stack backtrace:
CPU: 1 PID: 4468 Comm: syz.0.16 Not tainted 6.1.144-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call trace:
 dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
 dump_stack+0x1c/0x5c lib/dump_stack.c:113
 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2048
 check_noncircular+0x240/0x2d4 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x293c/0x6544 kernel/locking/lockdep.c:5049
 lock_acquire+0x20c/0x644 kernel/locking/lockdep.c:5662
 __might_fault+0xc4/0x124 mm/memory.c:5852
 _copy_to_user include/linux/uaccess.h:143 [inline]
 copy_to_user include/linux/uaccess.h:169 [inline]
 ni_fiemap+0x3fc/0x1030 fs/ntfs3/frecord.c:2140
 ntfs_fiemap+0xe4/0x140 fs/ntfs3/file.c:1170
 ioctl_fiemap fs/ioctl.c:219 [inline]
 do_vfs_ioctl+0x1694/0x206c fs/ioctl.c:810
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0xe4/0x1c8 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585