------------[ cut here ]------------
!buffer_uptodate(bh)
WARNING: fs/buffer.c:1183 at mark_buffer_dirty+0x299/0x3f0 fs/buffer.c:1183, CPU#0: syz.0.0/5347
Modules linked in:
CPU: 0 UID: 0 PID: 5347 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+0x299/0x3f0 fs/buffer.c:1183
Code: 4c 89 f7 e8 d9 62 db ff 49 8b 3e be 40 00 00 00 5b 41 5c 41 5e 41 5f 5d e9 b4 8a fb ff e8 3f d0 72 ff eb 8c e8 38 d0 72 ff 90 <0f> 0b 90 e9 a5 fd ff ff e8 2a d0 72 ff 90 0f 0b 90 e9 cf fd ff ff
RSP: 0018:ffffc90009f0e468 EFLAGS: 00010293
RAX: ffffffff824fd808 RBX: ffff88801c896cb0 RCX: ffff888000a18000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: ffff888012300001 R08: ffff88801c896cb7 R09: 1ffff11003912d96
R10: dffffc0000000000 R11: ffffed1003912d97 R12: ffff88801fd92400
R13: ffff88801c89a488 R14: ffff88801c896cb0 R15: 000000000000000b
FS:  00007f6e8cc4b6c0(0000) GS:ffff88808cf1d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000050 CR3: 0000000037fff000 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+0x6c6/0x1910 fs/buffer.c:2145
 block_write_begin+0x8d/0x120 fs/buffer.c:2256
 bfs_write_begin+0x35/0xd0 fs/bfs/file.c:180
 generic_perform_write+0x2e2/0x8f0 mm/filemap.c:4314
 generic_file_write_iter+0x14a/0x680 mm/filemap.c:4457
 __kernel_write_iter+0x41e/0x880 fs/read_write.c:619
 __kernel_write+0x106/0x170 fs/read_write.c:639
 __dump_emit+0x20b/0x320 fs/coredump.c:1220
 elf_core_dump+0x2e5d/0x3ad0 fs/binfmt_elf.c:2090
 coredump_write+0x11de/0x1980 fs/coredump.c:1049
 do_coredump fs/coredump.c:1126 [inline]
 vfs_coredump+0x369e/0x4270 fs/coredump.c:1200
 get_signal+0x1107/0x1330 kernel/signal.c:3019
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:75 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:270 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:339 [inline]
 irqentry_exit+0x176/0x620 kernel/entry/common.c:196
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x7f6e8bd9acc1
Code: 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 83 c8 ff c3 66 2e 0f 1f
RSP: 002b:0000000000000050 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f6e8c016180 RCX: 00007f6e8bd9acb9
RDX: 0000000000000000 RSI: 0000000000000050 RDI: 0000000000904000
RBP: 00007f6e8be08bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f6e8c016218 R14: 00007f6e8c016180 R15: 00007fffb259c5e8
 </TASK>