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
CPU: 1 PID: 3712 Comm: syz-executor7 Not tainted 4.18.0-rc3-next-20180709+ #2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:virt_to_head_page include/linux/mm.h:638 [inline]
RIP: 0010:virt_to_cache mm/slab.c:399 [inline]
RIP: 0010:kfree+0xa0/0x260 mm/slab.c:3809
Code: 82 cb 01 00 00 48 ba 00 00 00 80 ff 77 00 00 48 01 c2 48 89 df 48 b8 00 00 00 00 00 ea ff ff 48 c1 ea 0c 48 c1 e2 06 48 01 c2 <48> 8b 42 08 a8 01 48 8d 48 ff 48 0f 45 d1 4c 8b 6a 18 49 63 75 74 
RSP: 0018:ffff880195adf5d0 EFLAGS: 00010003
RAX: ffffea0000000000 RBX: 463246c986b65500 RCX: 1ffff10032b5bed8
RDX: 0118b4fb261ad940 RSI: ffffffff87700939 RDI: 463246c986b65500
RBP: ffff880195adf5f0 R08: ffff88019cf20500 R09: ffffed0032b5bdf8
R10: ffffed003b5e5930 R11: 0000000000000001 R12: 0000000000000286
R13: ffffffff87700973 R14: ffff880195adf740 R15: ffff880192730540
FS:  00007f4518ca2700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000047ad20 CR3: 00000001d7f48000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 p9_client_version net/9p/client.c:1009 [inline]
 p9_client_create+0xf43/0x16c9 net/9p/client.c:1069
 v9fs_session_init+0x21a/0x1a80 fs/9p/v9fs.c:400
 v9fs_mount+0x7c/0x900 fs/9p/vfs_super.c:135
 legacy_get_tree+0x118/0x440 fs/fs_context.c:659
 vfs_get_tree+0x1cb/0x5c0 fs/super.c:1751
 do_new_mount fs/namespace.c:2567 [inline]
 do_mount+0x6c1/0x1fb0 fs/namespace.c:2889
 ksys_mount+0x12d/0x140 fs/namespace.c:3105
 __do_sys_mount fs/namespace.c:3119 [inline]
 __se_sys_mount fs/namespace.c:3116 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3116
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x455e29
Code: 1d ba 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 b9 fb ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007f4518ca1c68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f4518ca26d4 RCX: 0000000000455e29
RDX: 0000000020000340 RSI: 00000000200000c0 RDI: 0000000000000000
RBP: 000000000072bea0 R08: 00000000200003c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000004c05ca R14: 00000000004d0070 R15: 0000000000000000
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
---[ end trace 081b70bb21bfef63 ]---
RIP: 0010:virt_to_head_page include/linux/mm.h:638 [inline]
RIP: 0010:virt_to_cache mm/slab.c:399 [inline]
RIP: 0010:kfree+0xa0/0x260 mm/slab.c:3809
Code: 82 cb 01 00 00 48 ba 00 00 00 80 ff 77 00 00 48 01 c2 48 89 df 48 b8 00 00 00 00 00 ea ff ff 48 c1 ea 0c 48 c1 e2 06 48 01 c2 <48> 8b 42 08 a8 01 48 8d 48 ff 48 0f 45 d1 4c 8b 6a 18 49 63 75 74 
RSP: 0018:ffff880195adf5d0 EFLAGS: 00010003
RAX: ffffea0000000000 RBX: 463246c986b65500 RCX: 1ffff10032b5bed8
RDX: 0118b4fb261ad940 RSI: ffffffff87700939 RDI: 463246c986b65500
RBP: ffff880195adf5f0 R08: ffff88019cf20500 R09: ffffed0032b5bdf8
R10: ffffed003b5e5930 R11: 0000000000000001 R12: 0000000000000286
R13: ffffffff87700973 R14: ffff880195adf740 R15: ffff880192730540
FS:  00007f4518ca2700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000047ad20 CR3: 00000001d7f48000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400