Re: WARNING in cgroup_apply_control_enable

[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit:    1ae80cf31938 bpf: wait for running BPF programs when updat..
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12b82735400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7e7e2279c0020d5f
dashboard link: https://syzkaller.appspot.com/bug?extid=5493b2a54d31d6aea629
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=120ead5e400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=132b7426400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+5493b2a54d31d6aea629@xxxxxxxxxxxxxxxxxxxxxxxxx

IPVS: ftp: loaded support on port[0] = 21
WARNING: CPU: 0 PID: 5812 at kernel/cgroup/cgroup.c:2931  
cgroup_apply_control_enable+0x22c/0xea0 kernel/cgroup/cgroup.c:2931
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 5812 Comm: syz-executor858 Not tainted 4.19.0-rc6+ #119
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
 panic+0x238/0x4e7 kernel/panic.c:184
 __warn.cold.8+0x163/0x1ba kernel/panic.c:536
 report_bug+0x254/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x1fc/0x4d0 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:993
RIP: 0010:cgroup_apply_control_enable+0x22c/0xea0  
kernel/cgroup/cgroup.c:2931
Code: 48 c1 e8 03 42 80 3c 28 00 0f 85 18 0a 00 00 49 8b 5f 18 31 ff 83 e3  
02 48 89 de e8 5e 60 07 00 48 85 db 74 07 e8 24 5f 07 00 <0f> 0b e8 1d 5f  
07 00 48 8b 85 a0 fe ff ff 48 c1 e8 03 42 80 3c 28
RSP: 0018:ffff8801bbe97808 EFLAGS: 00010293
RAX: ffff8801bbee2040 RBX: 0000000000000002 RCX: ffffffff81777662
RDX: 0000000000000000 RSI: ffffffff8177766c RDI: 0000000000000007
RBP: ffff8801bbe979b8 R08: ffff8801bbee2040 R09: fffffbfff1277dac
R10: ffff8801bbe97890 R11: ffffffff893bed67 R12: ffffffff893c50c0
R13: dffffc0000000000 R14: 000000000000000b R15: ffff8801d8f08a40
 cgroup_apply_control+0x1f/0x50 kernel/cgroup/cgroup.c:3017
 cgroup_enable_threaded kernel/cgroup/cgroup.c:3229 [inline]
 cgroup_type_write+0x3bb/0x580 kernel/cgroup/cgroup.c:3270
 cgroup_file_write+0x2f7/0x7e0 kernel/cgroup/cgroup.c:3450
 kernfs_fop_write+0x2ba/0x480 fs/kernfs/file.c:316
 __vfs_write+0x119/0x9f0 fs/read_write.c:485
 vfs_write+0x1fc/0x560 fs/read_write.c:549
 ksys_write+0x101/0x260 fs/read_write.c:598
 __do_sys_write fs/read_write.c:610 [inline]
 __se_sys_write fs/read_write.c:607 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:607
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x441d29
Code: e8 cc b2 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe2c31df58 EFLAGS: 00000213 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441d29
RDX: 0000000000000009 RSI: 0000000020000140 RDI: 0000000000000006
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000213 R12: 0000000000000001
R13: 000000000000bc4a R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..