------------[ cut here ]------------
!buffer_uptodate(bh)
WARNING: fs/buffer.c:1087 at mark_buffer_dirty+0x299/0x410, CPU#0: syz.1.35/5882
Modules linked in:
CPU: 0 UID: 0 PID: 5882 Comm: syz.1.35 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:mark_buffer_dirty+0x299/0x410
Code: 4c 89 f7 e8 b9 4a d8 ff 49 8b 3e be 40 00 00 00 5b 41 5c 41 5e 41 5f 5d e9 44 64 fb ff e8 ef 5e 6c ff eb 8c e8 e8 5e 6c ff 90 <0f> 0b 90 e9 a5 fd ff ff e8 da 5e 6c ff 90 0f 0b 90 e9 cf fd ff ff
RSP: 0018:ffffc90006c26408 EFLAGS: 00010293
RAX: ffffffff8258f3e8 RBX: ffff8881168c6658 RCX: ffff88810af85940
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 0000000000000201 R08: ffff8881168c665f R09: 1ffff11022d18ccb
R10: dffffc0000000000 R11: ffffed1022d18ccc R12: 000000000000000b
R13: ffff8881168c6658 R14: ffff8881168c6910 R15: dffffc0000000000
FS:  00007f406e0416c0(0000) GS:ffff88818dca4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f406e03ffd0 CR3: 000000011221e000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 bfs_get_block+0x5c6/0xb50
 __block_write_begin_int+0x6c2/0x1930
 block_write_begin+0x8d/0x120
 bfs_write_begin+0x35/0xd0
 generic_perform_write+0x2d5/0x8f0
 generic_file_write_iter+0x14a/0x680
 __kernel_write_iter+0x44a/0x8f0
 __kernel_write+0x106/0x170
 dump_emit+0x920/0xb00
 elf_core_dump+0x2ff4/0x3a90
 coredump_write+0x1290/0x19a0
 vfs_coredump+0x374c/0x4510
 get_signal+0x1094/0x12c0
 arch_do_signal_or_restart+0xbb/0x860
 irqentry_exit+0x2aa/0x8e0
 asm_exc_page_fault+0x26/0x30
RIP: 0033:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 002b:0000200000000008 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f406d415fa0 RCX: 00007f406d19ce59
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000000
RBP: 00007f406d232e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f406d416038 R14: 00007f406d415fa0 R15: 00007ffd8fc5ad38
 </TASK>
