folio != NULL
WARNING: fs/netfs/write_issue.c:603 at netfs_writepages+0x883/0xa10 fs/netfs/write_issue.c:603, CPU#3: syz.3.21683/21458
Modules linked in:
CPU: 3 UID: 0 PID: 21458 Comm: syz.3.21683 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:netfs_writepages+0x883/0xa10 fs/netfs/write_issue.c:603
Code: 48 89 df e8 0f 8b 7b ff 48 8b 4c 24 08 48 89 da 4c 89 e6 4c 89 f7 e8 bc 34 7f ff 48 85 c0 0f 84 c1 fe ff ff e8 ee c6 3d ff 90 <0f> 0b 90 e9 b3 fe ff ff e8 e0 c6 3d ff 48 b8 00 00 00 00 00 fc ff
RSP: 0018:ffffc90005db7178 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffffea0001146500 RCX: ffffffff824b4b6a
RDX: ffff888052deca80 RSI: ffffffff82cc0952 RDI: ffff888052deca80
RBP: fffffffffffffff4 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffc90005db7348
R13: ffff8880573d4680 R14: ffff8880573d4898 R15: dffffc0000000000
FS:  00007f5652fef6c0(0000) GS:ffff8880d60ec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000053611000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 do_writepages+0x278/0x600 mm/page-writeback.c:2571
 filemap_writeback+0x22d/0x2e0 mm/filemap.c:387
 v9fs_mmap_vm_close fs/9p/vfs_file.c:496 [inline]
 v9fs_mmap_vm_close+0x137/0x1e0 fs/9p/vfs_file.c:489
 vma_close mm/internal.h:190 [inline]
 vms_clean_up_area mm/vma.c:1318 [inline]
 __mmap_setup mm/vma.c:2476 [inline]
 __mmap_region+0x890/0x2db0 mm/vma.c:2756
 mmap_region+0x35d/0x620 mm/vma.c:2860
 do_mmap+0xc63/0x12f0 mm/mmap.c:560
 vm_mmap_pgoff+0x29e/0x470 mm/util.c:581
 ksys_mmap_pgoff+0xe4/0x610 mm/mmap.c:606
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:89 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:82 [inline]
 __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:82
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f565219de59
Code: ff c3 66 2e 0f 1f 84 00 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
RSP: 002b:00007f5652fef028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f5652425fa0 RCX: 00007f565219de59
RDX: 000000000200000a RSI: 0000000000200000 RDI: 0000200000000000
RBP: 00007f5652fef090 R08: ffffffffffffffff R09: 00000000ec776000
R10: 0000000000204031 R11: 0000000000000246 R12: 0000000000000001
R13: 00007f5652426038 R14: 00007f5652425fa0 R15: 00007ffd744db688
 </TASK>