invalid opcode in cgroup_mkdir

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: c6dd78fc Merge branch 'x86-urgent-for-linus' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11a25c10600000
kernel config: https://syzkaller.appspot.com/x/.config?x=3c8985c08e1f9727
dashboard link: https://syzkaller.appspot.com/bug?extid=3471d59f51e613697251
compiler: gcc (GCC) 9.0.0 20181231 (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+3471d5...@syzkaller.appspotmail.com

invalid opcode: 0000 [#1] SMP KASAN
CPU: 1 PID: 9701 Comm: syz-executor.0 Not tainted 5.2.0+ #64
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:cgroup_create /kernel/cgroup/cgroup.c:5307 [inline]
RIP: 0010:cgroup_mkdir+0xc86/0x1140 /kernel/cgroup/cgroup.c:5365
Code: 89 f9 48 c1 e9 03 0f b6 14 11 84 d2 74 09 80 fa 01 0f 8e cd 03 00 00
66 41 89 86 18 02 00 00 e8 c0 36 06 00 4c 89 f7 4d 89 f7 <4d> dd f5 e8 a2
69 ff ff e9 ff fa ff ff e8 a8 36 06 00 4c 89 f7 e8
RSP: 0018:ffff88808a8dfd30 EFLAGS: 00010293
RAX: ffff8880a96cc540 RBX: ffffffff88dc9db0 RCX: 0000000000000006
RDX: 0000000000000000 RSI: ffffffff816b1fc0 RDI: ffff88805d4a2500
RBP: ffff88808a8dfda8 R08: 1ffffffff14a6d40 R09: fffffbfff14a6d41
R10: fffffbfff14a6d40 R11: ffffffff8a536a07 R12: ffffffff88dc9e08
R13: ffff88805d4a2548 R14: ffff88805d4a2500 R15: ffff88805d4a2500
FS: 0000555556554940(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffdd1b62e80 CR3: 0000000093fe3000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
kernfs_iop_mkdir+0x14d/0x1d0 /fs/kernfs/dir.c:1123
vfs_mkdir+0x42e/0x670 /fs/namei.c:3815
do_mkdirat+0x234/0x2a0 /fs/namei.c:3838
__do_sys_mkdir /fs/namei.c:3854 [inline]
__se_sys_mkdir /fs/namei.c:3852 [inline]
__x64_sys_mkdir+0x5c/0x80 /fs/namei.c:3852
do_syscall_64+0xfd/0x6a0 /arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458c37
Code: 1f 40 00 b8 5a 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 cd c3 fb ff c3
66 2e 0f 1f 84 00 00 00 00 00 66 90 b8 53 00 00 00 0f 05 <48> 3d 01 f0 ff
ff 0f 83 ad c3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fff2e73ae78 EFLAGS: 00000206 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000458c37
RDX: 00007fff2e73aed7 RSI: 00000000000001ff RDI: 00007fff2e73aec0
RBP: 00000000000000f8 R08: 0000000000000000 R09: 0000000000000017
R10: 0000000000000075 R11: 0000000000000206 R12: 000000000075ca28
R13: 00007fff2e73b2e8 R14: 0000000000000000 R15: 00007fff2e73aec0
Modules linked in:
---[ end trace 14370be14633a2c7 ]---
RIP: 0010:cgroup_create /kernel/cgroup/cgroup.c:5307 [inline]
RIP: 0010:cgroup_mkdir+0xc86/0x1140 /kernel/cgroup/cgroup.c:5365
Code: 89 f9 48 c1 e9 03 0f b6 14 11 84 d2 74 09 80 fa 01 0f 8e cd 03 00 00
66 41 89 86 18 02 00 00 e8 c0 36 06 00 4c 89 f7 4d 89 f7 <4d> dd f5 e8 a2
69 ff ff e9 ff fa ff ff e8 a8 36 06 00 4c 89 f7 e8
RSP: 0018:ffff88808a8dfd30 EFLAGS: 00010293
RAX: ffff8880a96cc540 RBX: ffffffff88dc9db0 RCX: 0000000000000006
RDX: 0000000000000000 RSI: ffffffff816b1fc0 RDI: ffff88805d4a2500
RBP: ffff88808a8dfda8 R08: 1ffffffff14a6d40 R09: fffffbfff14a6d41
R10: fffffbfff14a6d40 R11: ffffffff8a536a07 R12: ffffffff88dc9e08
R13: ffff88805d4a2548 R14: ffff88805d4a2500 R15: ffff88805d4a2500
FS: 0000555556554940(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffdd1b62e80 CR3: 0000000093fe3000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.