kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 13017 Comm: syz-executor2 Not tainted 4.19.0-rc4-next-20180920+ #76
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:reconfigure_super+0x48e/0xbb0 fs/super.c:981
Code: 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 62 05 00 00 48 ba 00 00 00 00 00 fc ff df 48 8b 03 48 8d 78 30 48 89 f9 48 c1 e9 03 <80> 3c 11 00 0f 85 4d 05 00 00 48 8b 40 30 48 85 c0 48 89 85 20 ff
kobject: 'loop4' (0000000083b7277b): kobject_uevent_env
RSP: 0018:ffff88018f8278d8 EFLAGS: 00010206
RAX: 0000000000000000 RBX: ffff88018f8279f8 RCX: 0000000000000006
RDX: dffffc0000000000 RSI: ffffffff81cdb95b RDI: 0000000000000030
RBP: ffff88018f8279c8 R08: ffff8801bfad0500 R09: fffffbfff12c24e5
R10: fffffbfff12c24e5 R11: ffffffff8961272b R12: ffff88018f412cc0
R13: 1ffff10031f04f20 R14: 0000000000000000 R15: ffff88018f827adc
FS:  00007f678b1a1700(0000) GS:ffff8801dad00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f73ed6ac110 CR3: 00000001b756e000 CR4: 00000000001406e0
Call Trace:
kobject: 'loop4' (0000000083b7277b): fill_kobj_path: path = '/devices/virtual/block/loop4'
cgroup: fork rejected by pids controller in 
kobject: 'loop3' (0000000091a9257c): kobject_uevent_env
 do_umount_root+0x2b1/0x320 fs/namespace.c:1434
kobject: 'loop3' (0000000091a9257c): fill_kobj_path: path = '/devices/virtual/block/loop3'
 do_umount fs/namespace.c:1504 [inline]
 ksys_umount+0x8b6/0x1230 fs/namespace.c:1620
/syz3
kobject: 'loop4' (0000000083b7277b): kobject_uevent_env
kobject: 'loop4' (0000000083b7277b): fill_kobj_path: path = '/devices/virtual/block/loop4'
kobject: 'loop3' (0000000091a9257c): kobject_uevent_env
kobject: 'loop3' (0000000091a9257c): fill_kobj_path: path = '/devices/virtual/block/loop3'
kobject: 'loop4' (0000000083b7277b): kobject_uevent_env
kobject: 'loop4' (0000000083b7277b): fill_kobj_path: path = '/devices/virtual/block/loop4'
 __do_sys_umount fs/namespace.c:1631 [inline]
 __se_sys_umount fs/namespace.c:1629 [inline]
 __x64_sys_umount+0x54/0x80 fs/namespace.c:1629
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457679
Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f678b1a0c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: ffffffffffffffda RBX: 00007f678b1a16d4 RCX: 0000000000457679
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000080
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004d81a8 R14: 00000000004c4f0c R15: 0000000000000000
Modules linked in:
kobject: 'loop1' (000000007dbf0f12): kobject_uevent_env
---[ end trace 896591d775a3e8ce ]---
kobject: 'loop1' (000000007dbf0f12): fill_kobj_path: path = '/devices/virtual/block/loop1'
RIP: 0010:reconfigure_super+0x48e/0xbb0 fs/super.c:981
kobject: 'loop0' (00000000718116f9): kobject_uevent_env
Code: 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 62 05 00 00 48 ba 00 00 00 00 00 fc ff df 48 8b 03 48 8d 78 30 48 89 f9 48 c1 e9 03 <80> 3c 11 00 0f 85 4d 05 00 00 48 8b 40 30 48 85 c0 48 89 85 20 ff
kobject: 'loop0' (00000000718116f9): fill_kobj_path: path = '/devices/virtual/block/loop0'
RSP: 0018:ffff88018f8278d8 EFLAGS: 00010206
RAX: 0000000000000000 RBX: ffff88018f8279f8 RCX: 0000000000000006
RDX: dffffc0000000000 RSI: ffffffff81cdb95b RDI: 0000000000000030
RBP: ffff88018f8279c8 R08: ffff8801bfad0500 R09: fffffbfff12c24e5
R10: fffffbfff12c24e5 R11: ffffffff8961272b R12: ffff88018f412cc0
R13: 1ffff10031f04f20 R14: 0000000000000000 R15: ffff88018f827adc
FS:  00007f678b1a1700(0000) GS:ffff8801dac00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff754f6ff8 CR3: 00000001b756e000 CR4: 00000000001406f0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600