loop0: detected capacity change from 0 to 2048
------------[ cut here ]------------
!buffer_uptodate(bh)
WARNING: fs/buffer.c:991 at mark_buffer_dirty+0x299/0x410 fs/buffer.c:991, CPU#0: syz.0.0/5314
Modules linked in:
CPU: 0 UID: 0 PID: 5314 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:mark_buffer_dirty+0x299/0x410 fs/buffer.c:991
Code: 4c 89 f7 e8 d9 01 d8 ff 49 8b 3e be 40 00 00 00 5b 41 5c 41 5e 41 5f 5d e9 74 52 fb ff e8 6f 90 66 ff eb 8c e8 68 90 66 ff 90 <0f> 0b 90 e9 a5 fd ff ff e8 5a 90 66 ff 90 0f 0b 90 e9 cf fd ff ff
RSP: 0018:ffffc9000f5b7470 EFLAGS: 00010293
RAX: ffffffff82613bc8 RBX: ffff8880441f0a80 RCX: ffff888033c70000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: dffffc0000000001 R08: ffff8880441f0a87 R09: 1ffff1100883e150
R10: dffffc0000000000 R11: ffffed100883e151 R12: ffffffff8c289c40
R13: ffff888012f18248 R14: dffffc0000000000 R15: ffff88800bfb0788
FS:  00007f4aaf1b06c0(0000) GS:ffff88808c2cd000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000021000 CR3: 0000000036767000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 mmb_mark_buffer_dirty+0x2c/0x1f0 fs/buffer.c:624
 fat_ent_write+0xb8/0x190 fs/fat/fatent.c:422
 fat_chain_add+0x409/0x8e0 fs/fat/misc.c:140
 fat_add_cluster fs/fat/inode.c:113 [inline]
 __fat_get_block fs/fat/inode.c:155 [inline]
 fat_get_block+0x768/0xae0 fs/fat/inode.c:190
 __block_write_begin_int+0x6c2/0x1900 fs/buffer.c:2030
 block_write_begin fs/buffer.c:2144 [inline]
 cont_write_begin+0x71b/0xac0 fs/buffer.c:2506
 fat_write_begin+0x7a/0x150 fs/fat/inode.c:230
 generic_perform_write+0x2d5/0x8f0 mm/filemap.c:4374
 generic_file_write_iter+0xae/0x330 mm/filemap.c:4517
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4aae39e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4aaf1affe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f4aae625fa0 RCX: 00007f4aae39e159
RDX: 00000000fffffceb RSI: 00002000000001c0 RDI: 0000000000000006
RBP: 00007f4aae435024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4aae626038 R14: 00007f4aae625fa0 R15: 00007fff502f5788
 </TASK>