------------[ cut here ]------------
!buffer_uptodate(bh)
WARNING: fs/buffer.c:1087 at mark_buffer_dirty+0x299/0x410 fs/buffer.c:1087, CPU#0: syz.1.18/5882
Modules linked in:
CPU: 0 UID: 0 PID: 5882 Comm: syz.1.18 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 fs/buffer.c:1087
Code: 4c 89 f7 e8 59 4e d8 ff 49 8b 3e be 40 00 00 00 5b 41 5c 41 5e 41 5f 5d e9 44 64 fb ff e8 8f 62 6c ff eb 8c e8 88 62 6c ff 90 <0f> 0b 90 e9 a5 fd ff ff e8 7a 62 6c ff 90 0f 0b 90 e9 cf fd ff ff
RSP: 0018:ffffc9000278e348 EFLAGS: 00010293
RAX: ffffffff8258f048 RBX: ffff888113642488 RCX: ffff888106745940
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 0000000000000201 R08: ffff88811364248f R09: 1ffff110226c8491
R10: dffffc0000000000 R11: ffffed10226c8492 R12: 0000000000000011
R13: ffff888113642488 R14: ffff8881b79e79f8 R15: dffffc0000000000
FS:  00007f63e19dd6c0(0000) GS:ffff88818dca4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555648b87d0 CR3: 000000016a2f4000 CR4: 00000000000006f0
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+0x6c2/0x1930 fs/buffer.c:2042
 block_write_begin+0x8d/0x120 fs/buffer.c:2153
 bfs_write_begin+0x35/0xd0 fs/bfs/file.c:180
 generic_perform_write+0x2d5/0x8f0 mm/filemap.c:4347
 generic_file_write_iter+0x14a/0x680 mm/filemap.c:4490
 __kernel_write_iter+0x44a/0x8f0 fs/read_write.c:621
 __kernel_write+0x106/0x170 fs/read_write.c:641
 __dump_emit fs/coredump.c:1226 [inline]
 dump_emit+0x920/0xb00 fs/coredump.c:1264
 writenote+0x1c0/0x2f0 fs/binfmt_elf.c:1434
 write_note_info fs/binfmt_elf.c:1929 [inline]
 elf_core_dump+0x30f1/0x3a90 fs/binfmt_elf.c:2096
 coredump_write+0x1290/0x19a0 fs/coredump.c:1053
 do_coredump fs/coredump.c:1132 [inline]
 vfs_coredump+0x374c/0x4510 fs/coredump.c:1206
 get_signal+0x1094/0x12c0 kernel/signal.c:3022
 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:98 [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+0x2aa/0x8e0 kernel/entry/common.c:162
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
RIP: 0033:0x736662
Code: Unable to access opcode bytes at 0x736638.
RSP: 002b:0000200000000008 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f63e2616090 RCX: 00007f63e239ce59
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000000
RBP: 00007f63e2432e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f63e2616128 R14: 00007f63e2616090 R15: 00007ffecbed5df8
 </TASK>
