------------[ cut here ]------------
folio expected an open fid inode->i_ino=3a80143
WARNING: CPU: 0 PID: 1182 at fs/9p/vfs_addr.c:39 v9fs_begin_writeback fs/9p/vfs_addr.c:39 [inline]
WARNING: CPU: 0 PID: 1182 at fs/9p/vfs_addr.c:39 v9fs_begin_writeback+0x219/0x290 fs/9p/vfs_addr.c:33
Modules linked in:
CPU: 0 UID: 0 PID: 1182 Comm: kworker/u32:9 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: writeback wb_workfn (flush-9p-96)
RIP: 0010:v9fs_begin_writeback fs/9p/vfs_addr.c:39 [inline]
RIP: 0010:v9fs_begin_writeback+0x219/0x290 fs/9p/vfs_addr.c:33
Code: 00 00 00 00 00 fc ff df 48 8d 7b 40 48 89 fa 48 c1 ea 03 80 3c 02 00 75 66 48 8b 73 40 48 c7 c7 20 a9 d2 8b e8 f8 1f ed fd 90 <0f> 0b 90 90 e9 5f ff ff ff e8 39 6d 97 fe e9 4e ff ff ff e8 9f 6c
RSP: 0018:ffffc900061cf4a0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff88803d3b72c0 RCX: ffffffff817aaee8
RDX: ffff888029372480 RSI: ffffffff817aaef5 RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88804e27d350
R13: ffffc900061cf7d8 R14: dffffc0000000000 R15: ffff88804e27d5d8
FS:  0000000000000000(0000) GS:ffff8880d69dd000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020001000 CR3: 000000003970b000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 netfs_writepages+0x6e4/0x920 fs/netfs/write_issue.c:591
 do_writepages+0x27a/0x600 mm/page-writeback.c:2604
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1719
 writeback_sb_inodes+0x60d/0xfa0 fs/fs-writeback.c:2015
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2195
 wb_do_writeback fs/fs-writeback.c:2342 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2382
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3263
 process_scheduled_works kernel/workqueue.c:3346 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3427
 kthread+0x3c2/0x780 kernel/kthread.c:463
 ret_from_fork+0x672/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>