general protection fault in eventfd_ctx_remove_wait_queue

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    75bc37fefc44 Linux 4.17-rc4
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=161de3c7800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=31f4b3733894ef79
dashboard link: https://syzkaller.appspot.com/bug?extid=f8c4b79b3cb98d795e59
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+f8c4b79b3cb98d795e59@xxxxxxxxxxxxxxxxxxxxxxxxx

IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready
8021q: adding VLAN 0 to HW filter on device team0
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 4 Comm: kworker/0:0 Not tainted 4.17.0-rc4+ #37
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: kvm-irqfd-cleanup irqfd_shutdown
RIP: 0010:__list_del_entry_valid+0x84/0xf3 lib/list_debug.c:51
RSP: 0018:ffff8801d9a7f588 EFLAGS: 00010046
RAX: dffffc0000000000 RBX: ffff8801a87665e0 RCX: 1ffff1003644b29a
RDX: 0000000000000000 RSI: ffffffff81d628fe RDI: ffff8801a87665e8
RBP: ffff8801d9a7f5a0 R08: ffff8801d9a6a100 R09: ffffed003644b291
R10: ffffed003644b291 R11: ffff8801b225948b R12: 0000000000000000
R13: 0000000000000000 R14: ffff8801a87665e0 R15: ffff8801d9a7f688
FS:  0000000000000000(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1d83a8d000 CR3: 00000001cf4a2000 CR4: 00000000001426f0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 __list_del_entry include/linux/list.h:117 [inline]
 list_del include/linux/list.h:125 [inline]
 __remove_wait_queue include/linux/wait.h:184 [inline]
 eventfd_ctx_remove_wait_queue+0x16f/0x590 fs/eventfd.c:188
 irqfd_shutdown+0x94/0x1a0 arch/x86/kvm/../../../virt/kvm/eventfd.c:128
 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145
 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279
 kthread+0x345/0x410 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
Code: c5 0f 84 cc 00 00 00 48 b8 00 02 00 00 00 00 ad de 49 39 c4 0f 84 a5  
00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00  
75 5f 49 8b 14 24 48 39 da 0f 85 ba 00 00 00 48 b8
RIP: __list_del_entry_valid+0x84/0xf3 lib/list_debug.c:51 RSP:  
ffff8801d9a7f588
---[ end trace 115284d8987d1fc5 ]---


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