syzbot

======================================================
WARNING: possible circular locking dependency detected
6.16.0-syzkaller #0 Not tainted
------------------------------------------------------
syz.0.22/6088 is trying to acquire lock:
ffff8880271db3e0 (&mm->mmap_lock){++++}-{4:4}, at: gup_fast_fallback+0x215/0x2260 mm/gup.c:3347

but task is already holding lock:
ffff888059e53e58 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:869 [inline]
ffff888059e53e58 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: __blockdev_direct_IO+0x32a/0x33d0 fs/direct-io.c:1140

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
       down_write+0x96/0x1f0 kernel/locking/rwsem.c:1577
       inode_lock include/linux/fs.h:869 [inline]
       ntfs_file_mmap+0x525/0x730 fs/ntfs3/file.c:313
       call_mmap include/linux/fs.h:2286 [inline]
       mmap_file mm/internal.h:167 [inline]
       __mmap_new_file_vma mm/vma.c:2405 [inline]
       __mmap_new_vma mm/vma.c:2467 [inline]
       __mmap_region mm/vma.c:2622 [inline]
       mmap_region+0x1277/0x1f30 mm/vma.c:2692
       do_mmap+0xc45/0x10d0 mm/mmap.c:561
       vm_mmap_pgoff+0x31b/0x4c0 mm/util.c:579
       ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:607
       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 (&mm->mmap_lock){++++}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3168 [inline]
       check_prevs_add kernel/locking/lockdep.c:3287 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
       gup_fast_fallback+0x22e/0x2260 mm/gup.c:3347
       iov_iter_extract_user_pages lib/iov_iter.c:1846 [inline]
       iov_iter_extract_pages+0x35a/0x5e0 lib/iov_iter.c:1909
       dio_refill_pages fs/direct-io.c:172 [inline]
       dio_get_page fs/direct-io.c:213 [inline]
       do_direct_IO fs/direct-io.c:915 [inline]
       __blockdev_direct_IO+0x114f/0x33d0 fs/direct-io.c:1243
       blockdev_direct_IO include/linux/fs.h:3477 [inline]
       ntfs_direct_IO+0x20b/0x410 fs/ntfs3/inode.c:813
       generic_file_read_iter+0x319/0x510 mm/filemap.c:2880
       new_sync_read fs/read_write.c:491 [inline]
       vfs_read+0x4d0/0x980 fs/read_write.c:572
       ksys_read+0x145/0x250 fs/read_write.c:715
       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(&sb->s_type->i_mutex_key#24);
                               lock(&mm->mmap_lock);
                               lock(&sb->s_type->i_mutex_key#24);
  rlock(&mm->mmap_lock);

 *** DEADLOCK ***

2 locks held by syz.0.22/6088:
 #0: ffff888034b97cf8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x247/0x320 fs/file.c:1217
 #1: ffff888059e53e58 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:869 [inline]
 #1: ffff888059e53e58 (&sb->s_type->i_mutex_key#24){+.+.}-{4:4}, at: __blockdev_direct_IO+0x32a/0x33d0 fs/direct-io.c:1140

stack backtrace:
CPU: 0 UID: 0 PID: 6088 Comm: syz.0.22 Not tainted 6.16.0-syzkaller #0 PREEMPT(full) 
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:2046
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3168 [inline]
 check_prevs_add kernel/locking/lockdep.c:3287 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
 gup_fast_fallback+0x22e/0x2260 mm/gup.c:3347
 iov_iter_extract_user_pages lib/iov_iter.c:1846 [inline]
 iov_iter_extract_pages+0x35a/0x5e0 lib/iov_iter.c:1909
 dio_refill_pages fs/direct-io.c:172 [inline]
 dio_get_page fs/direct-io.c:213 [inline]
 do_direct_IO fs/direct-io.c:915 [inline]
 __blockdev_direct_IO+0x114f/0x33d0 fs/direct-io.c:1243
 blockdev_direct_IO include/linux/fs.h:3477 [inline]
 ntfs_direct_IO+0x20b/0x410 fs/ntfs3/inode.c:813
 generic_file_read_iter+0x319/0x510 mm/filemap.c:2880
 new_sync_read fs/read_write.c:491 [inline]
 vfs_read+0x4d0/0x980 fs/read_write.c:572
 ksys_read+0x145/0x250 fs/read_write.c:715
 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: 0033:0x7f136378e9a9
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:00007f13645bf038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f13639b5fa0 RCX: 00007f136378e9a9
RDX: 0000000000001000 RSI: 0000200000001400 RDI: 0000000000000005
RBP: 00007f1363810d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f13639b5fa0 R15: 00007ffc0ac04ff8
 </TASK>