BUG: unable to handle kernel paging request in refcount_inc_not_zero_checked

[syzbot <syzbot+e593df3bb8f541d497b9@syzkaller.appspotmail.com>]

Hello,

syzbot found the following crash on:

HEAD commit:    570b7bdeaf18 Add linux-next specific files for 20181009
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15f27959400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9b5a60e1381390c4
dashboard link: https://syzkaller.appspot.com/bug?extid=e593df3bb8f541d497b9
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e593df3bb8f541d497b9@syzkaller.appspotmail.com

BUG: unable to handle kernel paging request at ffffc90001b356b0
PGD 1da948067 P4D 1da948067 PUD 1da949067 PMD 1ce844067 PTE 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 11542 Comm: syz-executor2 Not tainted 4.19.0-rc7-next-20181009+  
#90
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
kobject: 'queues' (00000000da0a0759): kobject_uevent_env
RIP: 0010:__read_once_size include/linux/compiler.h:179 [inline]
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:31 [inline]
RIP: 0010:atomic_read include/asm-generic/atomic-instrumented.h:22 [inline]
RIP: 0010:refcount_inc_not_zero_checked+0xbb/0x2f0 lib/refcount.c:120
Code: e7 e8 89 4b 30 fe 4c 89 e0 48 c1 e8 03 0f b6 14 18 4c 89 e0 83 e0 07  
83 c0 03 38 d0 7c 08 84 d2 0f 85 0b 02 00 00 49 8d 5d c0 <45> 8b 3c 24 48  
b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 0f
kobject: 'queues' (00000000da0a0759): kobject_uevent_env: filter function  
caused the event to drop!
RSP: 0018:ffff88017cf9f618 EFLAGS: 00010246
RAX: 0000000000000003 RBX: ffff88017cf9f690 RCX: ffffffff83929317
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffc90001b356b0
RBP: ffff88017cf9f6f8 R08: fffff52000366ad7 R09: fffff52000366ad6
R10: fffff52000366ad6 R11: ffffc90001b356b3 R12: ffffc90001b356b0
R13: ffff88017cf9f6d0 R14: ffffffff892b6d60 R15: ffff8801d4803400
FS:  00007fb683cfa700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kobject: 'loop1' (00000000bc5d5992): kobject_uevent_env
CR2: ffffc90001b356b0 CR3: 00000001d2369000 CR4: 00000000001426e0
netlink: 72 bytes leftover after parsing attributes in process  
`syz-executor3'.
Call Trace:
  refcount_inc_checked+0x15/0x70 lib/refcount.c:153
kobject: 'loop1' (00000000bc5d5992): fill_kobj_path: path  
= '/devices/virtual/block/loop1'
  kvm_get_kvm arch/x86/kvm/../../../virt/kvm/kvm_main.c:765 [inline]
  kvm_ioctl_create_device arch/x86/kvm/../../../virt/kvm/kvm_main.c:2923  
[inline]
  kvm_vm_ioctl+0xedf/0x1d60 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3113
  vfs_ioctl fs/ioctl.c:46 [inline]
  file_ioctl fs/ioctl.c:501 [inline]
  do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
  __do_sys_ioctl fs/ioctl.c:709 [inline]
  __se_sys_ioctl fs/ioctl.c:707 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457579
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:00007fb683cf9c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457579
RDX: 00000000200002c0 RSI: 00000000c00caee0 RDI: 0000000000000008
RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb683cfa6d4
R13: 00000000004bfbd1 R14: 00000000004cfc58 R15: 00000000ffffffff
Modules linked in:
CR2: ffffc90001b356b0
---[ end trace 6ee8acb8091e879f ]---
RIP: 0010:__read_once_size include/linux/compiler.h:179 [inline]
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:31 [inline]
RIP: 0010:atomic_read include/asm-generic/atomic-instrumented.h:22 [inline]
RIP: 0010:refcount_inc_not_zero_checked+0xbb/0x2f0 lib/refcount.c:120
Code: e7 e8 89 4b 30 fe 4c 89 e0 48 c1 e8 03 0f b6 14 18 4c 89 e0 83 e0 07  
83 c0 03 38 d0 7c 08 84 d2 0f 85 0b 02 00 00 49 8d 5d c0 <45> 8b 3c 24 48  
b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 0f
RSP: 0018:ffff88017cf9f618 EFLAGS: 00010246
RAX: 0000000000000003 RBX: ffff88017cf9f690 RCX: ffffffff83929317
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffffc90001b356b0
RBP: ffff88017cf9f6f8 R08: fffff52000366ad7 R09: fffff52000366ad6
R10: fffff52000366ad6 R11: ffffc90001b356b3 R12: ffffc90001b356b0
R13: ffff88017cf9f6d0 R14: ffffffff892b6d60 R15: ffff8801d4803400
FS:  00007fb683cfa700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffc90001b356b0 CR3: 00000001d2369000 CR4: 00000000001426e0


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