------------[ cut here ]------------
!sb->s_dev
WARNING: fs/super.c:509 at super_dev_register+0xf8/0x250 fs/super.c:509, CPU#0: syz.2.236/6845
Modules linked in:
CPU: 0 UID: 0 PID: 6845 Comm: syz.2.236 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:super_dev_register+0xf8/0x250 fs/super.c:509
Code: 04 38 84 c0 0f 85 34 01 00 00 8b 2b 31 ff 89 ee e8 0d 22 85 ff 85 ed 0f 85 98 00 00 00 e8 50 1d 85 ff eb 17 e8 49 1d 85 ff 90 <0f> 0b 90 48 85 db 75 c4 e8 3b 1d 85 ff 90 0f 0b 90 43 0f b6 04 3c
RSP: 0018:ffffc90004fef9d0 EFLAGS: 00010283
RAX: ffffffff823fff87 RBX: ffff88803ca6d200 RCX: 0000000000080000
RDX: ffffc9000dee1000 RSI: 00000000000009fc RDI: 00000000000009fd
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff82400990 R12: 1ffff1100dc01402
R13: dffffc0000000000 R14: ffff88806e00a010 R15: dffffc0000000000
FS:  00007f28565f66c0(0000) GS:ffff888125c49000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32d1bff8 CR3: 000000003fca8000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 sget_fc+0x12f6/0x1a60 fs/super.c:896
 sget_dev fs/super.c:1480 [inline]
 get_tree_bdev_flags+0x212/0x4f0 fs/super.c:1867
 fuse_get_tree+0x194/0x3b0 fs/fuse/inode.c:1877
 vfs_get_tree+0x92/0x2a0 fs/super.c:1941
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3777 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3853
 do_mount fs/namespace.c:4186 [inline]
 __do_sys_mount fs/namespace.c:4402 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4379
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f285839de59
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:00007f28565f6028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f2858625fa0 RCX: 00007f285839de59
RDX: 0000200000000080 RSI: 00002000000000c0 RDI: 00002000000001c0
RBP: 00007f2858433e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2858626038 R14: 00007f2858625fa0 R15: 00007ffcfe576448
 </TASK>