------------[ cut here ]------------
WARNING: CPU: 0 PID: 5330 at fs/buffer.c:1183 mark_buffer_dirty+0x2a9/0x410 fs/buffer.c:1183
Modules linked in:
CPU: 0 UID: 0 PID: 5330 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~bpo12+1 04/01/2014
RIP: 0010:mark_buffer_dirty+0x2a9/0x410 fs/buffer.c:1183
Code: 4c 89 f7 e8 69 08 dd ff 49 8b 3e be 40 00 00 00 5b 41 5c 41 5e 41 5f 5d e9 14 ea fb ff e8 ff bc 75 ff eb 8c e8 f8 bc 75 ff 90 <0f> 0b 90 e9 95 fd ff ff e8 ea bc 75 ff 90 0f 0b 90 e9 bf fd ff ff
RSP: 0018:ffffc9000d3c64a8 EFLAGS: 00010293
RAX: ffffffff824a5658 RBX: ffff8880448131d0 RCX: ffff8880007f8000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: ffff888032d90001 R08: ffff8880448131d7 R09: 1ffff1100890263a
R10: dffffc0000000000 R11: ffffed100890263b R12: ffff88804b9c8c00
R13: ffff888012009000 R14: ffff8880448131d0 R15: 000000000000000c
FS:  00007f7144b826c0(0000) GS:ffff88808d72f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000002000 CR3: 0000000041f04000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 bfs_move_block fs/bfs/file.c:44 [inline]
 bfs_move_blocks fs/bfs/file.c:57 [inline]
 bfs_get_block+0x5da/0xae0 fs/bfs/file.c:126
 __block_write_begin_int+0x6b5/0x1900 fs/buffer.c:2145
 block_write_begin+0x8a/0x120 fs/buffer.c:2256
 bfs_write_begin+0x35/0xd0 fs/bfs/file.c:180
 generic_perform_write+0x2c5/0x900 mm/filemap.c:4254
 generic_file_write_iter+0x117/0x550 mm/filemap.c:4397
 __kernel_write_iter+0x428/0x910 fs/read_write.c:619
 __kernel_write+0xef/0x150 fs/read_write.c:639
 __dump_emit+0x206/0x310 fs/coredump.c:1220
 writenote+0x1be/0x2e0 fs/binfmt_elf.c:1434
 write_note_info fs/binfmt_elf.c:1946 [inline]
 elf_core_dump+0x2f17/0x3960 fs/binfmt_elf.c:2098
 coredump_write+0x116c/0x1900 fs/coredump.c:1049
 vfs_coredump+0x1db5/0x2a60 fs/coredump.c:1170
 get_signal+0x1108/0x1340 kernel/signal.c:3019
 arch_do_signal_or_restart+0xa0/0x790 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:40 [inline]
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 irqentry_exit_to_user_mode+0x7e/0x110 kernel/entry/common.c:73
 exc_page_fault+0xab/0x100 arch/x86/mm/fault.c:1535
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7f7143d8f751
Code: 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 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:fffffffffffffea0 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f7143fe5fa0 RCX: 00007f7143d8f749
RDX: 0000000000000000 RSI: fffffffffffffea0 RDI: 0000000000000000
RBP: 00007f7143e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7143fe6038 R14: 00007f7143fe5fa0 R15: 00007fffb7196d08
 </TASK>