BUG: corrupted list in __dentry_kill

[syzbot]

Hello,

syzbot hit the following crash on bpf-next commit
7828f20e3779e4e85e55371e0e43f5006a15fb41 (Sat Mar 31 00:17:57 2018 +0000)
Merge branch 'bpf-cgroup-bind-connect'
syzbot dashboard link:  
https://syzkaller.appspot.com/bug?extid=f3bd89a5ab3266b10540

So far this crash happened 22 times on bpf-next, upstream.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6290970458980352
syzkaller reproducer:  
https://syzkaller.appspot.com/x/repro.syz?id=6577156880596992
Raw console output:  
https://syzkaller.appspot.com/x/log.txt?id=5107570603720704
Kernel config:  
https://syzkaller.appspot.com/x/.config?id=5909223872832634926
compiler: gcc (GCC) 7.1.1 20170620

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Reported-by: syzbot+f3bd89a5ab3266b10540@xxxxxxxxxxxxxxxxxxxxxxxxx
It will help syzbot understand when the bug is fixed. See footer for  
details.
If you forward the report, please keep this part and the footer.

RBP: 00007ffd1bbb3ae0 R08: 0000000020000200 R09: 0000000300000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000003 R14: 0000000000001380 R15: 00007ffd1bbb3378
list_del corruption. prev->next should be 00000000a8104008, but was  
00000000081c6144
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:53!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 4448 Comm: syzkaller853443 Not tainted 4.16.0-rc6+ #43
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:__list_del_entry_valid+0xef/0x150 lib/list_debug.c:51
RSP: 0018:ffff8801b8f977a0 EFLAGS: 00010282
RAX: 0000000000000054 RBX: ffff8801b0c1cf60 RCX: 0000000000000000
RDX: 0000000000000054 RSI: 1ffff100371f2ea9 RDI: ffffed00371f2ee8
RBP: ffff8801b8f977b8 R08: 1ffff100371f2e40 R09: 0000000000000000
R10: ffff8801b8f97778 R11: 0000000000000000 R12: ffff8801b0c1cde0
R13: 1ffff100371f2efd R14: ffff8801b0c1cc70 R15: dffffc0000000000
FS:  00000000023a5880(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004b6fbc CR3: 00000001c85a6004 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __list_del_entry include/linux/list.h:117 [inline]
 dentry_unlist fs/dcache.c:518 [inline]
 __dentry_kill+0x260/0x700 fs/dcache.c:571
 dentry_kill fs/dcache.c:616 [inline]
 dput.part.20+0x5a0/0x830 fs/dcache.c:831
 dput+0x1f/0x30 fs/dcache.c:795
 rpc_gssd_dummy_depopulate net/sunrpc/rpc_pipe.c:1381 [inline]
 rpc_fill_super+0x628/0xae0 net/sunrpc/rpc_pipe.c:1426
 mount_ns+0xc4/0x190 fs/super.c:1036
 rpc_mount+0x9e/0xd0 net/sunrpc/rpc_pipe.c:1451
 mount_fs+0x66/0x2d0 fs/super.c:1222
 vfs_kern_mount.part.26+0xc6/0x4a0 fs/namespace.c:1037
 vfs_kern_mount fs/namespace.c:2509 [inline]
 do_new_mount fs/namespace.c:2512 [inline]
 do_mount+0xea4/0x2bb0 fs/namespace.c:2842
 SYSC_mount fs/namespace.c:3058 [inline]
 SyS_mount+0xab/0x120 fs/namespace.c:3035
 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x442759
RSP: 002b:00007ffd1bbb3238 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000442759
RDX: 00000000200002c0 RSI: 0000000020000140 RDI: 0000000020000300
RBP: 00007ffd1bbb3ae0 R08: 0000000020000200 R09: 0000000300000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000003 R14: 0000000000001380 R15: 00007ffd1bbb3378
Code: 4c 89 e2 48 c7 c7 c0 bf 75 87 e8 35 c1 46 fe 0f 0b 48 c7 c7 20 c0 75  
87 e8 27 c1 46 fe 0f 0b 48 c7 c7 80 c0 75 87 e8 19 c1 46 fe <0f> 0b 48 c7  
c7 e0 c0 75 87 e8 0b c1 46 fe 0f 0b 48 89 df 48 89
RIP: __list_del_entry_valid+0xef/0x150 lib/list_debug.c:51 RSP:  
ffff8801b8f977a0
---[ end trace e1b9954cded9aca7 ]---


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