------------[ cut here ]------------
WARNING: CPU: 0 PID: 27574 at block/genhd.c:547 device_add_disk+0xb3b/0xcf0 block/genhd.c:547
Modules linked in:
CPU: 0 PID: 27574 Comm: syz-executor.1 Not tainted 5.14.0-rc6-next-20210818-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:device_add_disk+0xb3b/0xcf0 block/genhd.c:547
Code: fa ff ff 4c 89 e7 89 44 24 18 e8 a0 34 f5 fd 8b 44 24 18 e9 06 fb ff ff 4c 89 e7 e8 1f 34 f5 fd e9 b4 fb ff ff e8 95 68 af fd <0f> 0b e9 4c fb ff ff 4c 89 ff e8 16 34 f5 fd e9 ef f4 ff ff 48 8b
RSP: 0018:ffffc90014eb7d98 EFLAGS: 00010246
RAX: 0000000000040000 RBX: ffff8880765d8bc0 RCX: ffffc9000606a000
RDX: 0000000000040000 RSI: ffffffff83c6fe6b RDI: 0000000000000003
RBP: ffff88807ebcf800 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff83c6f9b2 R11: 0000000000000000 R12: ffff8880765d90a4
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88807ebcf890
FS:  00007f92cca60700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000540198 CR3: 000000003bd71000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 add_disk include/linux/genhd.h:222 [inline]
 loop_add+0x761/0x940 drivers/block/loop.c:2396
 loop_control_ioctl+0x130/0x450 drivers/block/loop.c:2493
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __x64_sys_ioctl+0x19b/0x210 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665e9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f92cca60188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665e9
RDX: 9999999999999999 RSI: 0000000000004c80 RDI: 0000000000000003
RBP: 00007f92cca601d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002
R13: 00007ffcde3f10bf R14: 00007f92cca60300 R15: 0000000000022000
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	ff 4c 89 e7          	decl   -0x19(%rcx,%rcx,4)
   4:	89 44 24 18          	mov    %eax,0x18(%rsp)
   8:	e8 a0 34 f5 fd       	callq  0xfdf534ad
   d:	8b 44 24 18          	mov    0x18(%rsp),%eax
  11:	e9 06 fb ff ff       	jmpq   0xfffffb1c
  16:	4c 89 e7             	mov    %r12,%rdi
  19:	e8 1f 34 f5 fd       	callq  0xfdf5343d
  1e:	e9 b4 fb ff ff       	jmpq   0xfffffbd7
  23:	e8 95 68 af fd       	callq  0xfdaf68bd
  28:	0f 0b                	ud2     <-- trapping instruction
  2a:	e9 4c fb ff ff       	jmpq   0xfffffb7b
  2f:	4c 89 ff             	mov    %r15,%rdi
  32:	e8 16 34 f5 fd       	callq  0xfdf5344d
  37:	e9 ef f4 ff ff       	jmpq   0xfffff52b
  3c:	48                   	rex.W
  3d:	8b                   	.byte 0x8b