------------[ cut here ]------------
!buffer_uptodate(bh)
WARNING: fs/buffer.c:991 at mark_buffer_dirty+0x299/0x410 fs/buffer.c:991, CPU#0: syz.0.0/5325
Modules linked in:
CPU: 0 UID: 0 PID: 5325 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 d5 d7 ff 49 8b 3e be 40 00 00 00 5b 41 5c 41 5e 41 5f 5d e9 34 44 fb ff e8 8f 56 65 ff eb 8c e8 88 56 65 ff 90 <0f> 0b 90 e9 a5 fd ff ff e8 7a 56 65 ff 90 0f 0b 90 e9 cf fd ff ff
RSP: 0000:ffffc9000df7e728 EFLAGS: 00010293
RAX: ffffffff8262caf8 RBX: ffff888044d6dee0 RCX: ffff88801324a580
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 0000000000000201 R08: ffff888044d6dee7 R09: 1ffff110089adbdc
R10: dffffc0000000000 R11: ffffed10089adbdd R12: 000000000000000a
R13: ffff888044d6dee0 R14: ffff88801440ae00 R15: dffffc0000000000
FS:  00007f312445f6c0(0000) GS:ffff88808b0b4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f31174bc000 CR3: 0000000050bcb000 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+0x5c6/0xb50 fs/bfs/file.c:126
 __block_write_begin_int+0x6c2/0x1900 fs/buffer.c:2030
 block_write_begin+0x8d/0x120 fs/buffer.c:2144
 bfs_write_begin+0x35/0xd0 fs/bfs/file.c:180
 generic_perform_write+0x2d5/0x8f0 mm/filemap.c:4374
 generic_file_write_iter+0xae/0x330 mm/filemap.c:4517
 __kernel_write_iter+0x44a/0x8f0 fs/read_write.c:621
 dump_emit_page fs/coredump.c:1293 [inline]
 dump_user_range+0xc19/0x12c0 fs/coredump.c:1367
 elf_core_dump+0x3485/0x3a90 fs/binfmt_elf.c:2106
 coredump_write+0x1290/0x1960 fs/coredump.c:1047
 do_coredump fs/coredump.c:1126 [inline]
 vfs_coredump+0x3764/0x4520 fs/coredump.c:1195
 get_signal+0x1094/0x12c0 kernel/signal.c:3097
 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:101 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:244 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:315 [inline]
 irqentry_exit+0x2c0/0x920 kernel/entry/common.c:165
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0033:0x7f312359e2e1
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:00000000fffffeb0 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f3123826180 RCX: 00007f312359e2d9
RDX: 0000000000000000 RSI: 00000000fffffeb0 RDI: 0000000002000400
RBP: 00007f3123635888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f3123826218 R14: 00007f3123826180 R15: 00007ffebb94a558
 </TASK>