------------[ cut here ]------------
folio expected an open fid inode->i_ino=3b4148b
WARNING: fs/9p/vfs_addr.c:39 at v9fs_begin_writeback fs/9p/vfs_addr.c:39 [inline], CPU#0: kworker/u32:2/46
WARNING: fs/9p/vfs_addr.c:39 at v9fs_begin_writeback+0x1f2/0x260 fs/9p/vfs_addr.c:33, CPU#0: kworker/u32:2/46
Modules linked in:
CPU: 0 UID: 0 PID: 46 Comm: kworker/u32:2 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
Workqueue: writeback wb_workfn (flush-9p-33)
RIP: 0010:v9fs_begin_writeback fs/9p/vfs_addr.c:39 [inline]
RIP: 0010:v9fs_begin_writeback+0x1f6/0x260 fs/9p/vfs_addr.c:33
Code: 90 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 40 48 89 fa 48 c1 ea 03 80 3c 02 00 75 6b 48 8d 3d 4e 5e fe 0c 48 8b 73 40 <67> 48 0f b9 3a eb 84 e8 fe d5 91 fe e9 9e fe ff ff e8 84 d6 91 fe
RSP: 0018:ffffc900007ef458 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff888041c65940 RCX: 0000000000000000
RDX: 1ffff1100838cb30 RSI: 0000000003b4148b RDI: ffffffff90e187f0
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffed100838cb38
R10: ffff888041c659c3 R11: 0000000000000000 R12: ffff88803765b510
R13: ffffc900007ef7b8 R14: ffff88803765b798 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880d6347000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f79bcf68ff8 CR3: 0000000031205000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 netfs_writepages+0x728/0x990 fs/netfs/write_issue.c:592
 do_writepages+0x278/0x600 mm/page-writeback.c:2554
 __writeback_single_inode+0x164/0x13c0 fs/fs-writeback.c:1750
 writeback_sb_inodes+0x766/0x1c70 fs/fs-writeback.c:2042
 wb_writeback+0x1c0/0xbe0 fs/fs-writeback.c:2227
 wb_do_writeback fs/fs-writeback.c:2374 [inline]
 wb_workfn+0x142/0xc00 fs/fs-writeback.c:2414
 process_one_work+0x9d7/0x1920 kernel/workqueue.c:3275
 process_scheduled_works kernel/workqueue.c:3358 [inline]
 worker_thread+0x5da/0xe40 kernel/workqueue.c:3439
 kthread+0x370/0x450 kernel/kthread.c:467
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
----------------
Code disassembly (best guess):
   0:	90                   	nop
   1:	00 00                	add    %al,(%rax)
   3:	00 48 b8             	add    %cl,-0x48(%rax)
   6:	00 00                	add    %al,(%rax)
   8:	00 00                	add    %al,(%rax)
   a:	00 fc                	add    %bh,%ah
   c:	ff                   	lcall  (bad)
   d:	df 48 8d             	fisttps -0x73(%rax)
  10:	7b 40                	jnp    0x52
  12:	48 89 fa             	mov    %rdi,%rdx
  15:	48 c1 ea 03          	shr    $0x3,%rdx
  19:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
  1d:	75 6b                	jne    0x8a
  1f:	48 8d 3d 4e 5e fe 0c 	lea    0xcfe5e4e(%rip),%rdi        # 0xcfe5e74
  26:	48 8b 73 40          	mov    0x40(%rbx),%rsi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	eb 84                	jmp    0xffffffb5
  31:	e8 fe d5 91 fe       	call   0xfe91d634
  36:	e9 9e fe ff ff       	jmp    0xfffffed9
  3b:	e8 84 d6 91 fe       	call   0xfe91d6c4