general protection fault in cpuacct_charge

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    8ae71e76cf1f Merge branch 'bpf-offload-sharing'
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1645f978400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=89129667b46496c3
dashboard link: https://syzkaller.appspot.com/bug?extid=a22ee0b9ff4d252439f4
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+a22ee0b9ff4d252439f4@xxxxxxxxxxxxxxxxxxxxxxxxx

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: 0 Comm: ïG+ï
ïïï0xïïïïïï Not tainted 4.18.0-rc3+ #58
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:task_css include/linux/cgroup.h:477 [inline]
RIP: 0010:task_ca kernel/sched/cpuacct.c:43 [inline]
RIP: 0010:cpuacct_charge+0x1b8/0x5d0 kernel/sched/cpuacct.c:349
Code: 68 ff ff ff 85 c0 74 0d 80 3d 45 31 3c 08 00 0f 84 04 02 00 00 48 b8  
00 00 00 00 00 fc ff df 49 8d 7d 10 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f  
85 65 03 00 00 4d 8b 65 10 4d 85 e4 0f 84 0a 01 00
RSP: 0018:ffff8801daf072b0 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: ffff8801c72b40c0 RCX: 0000000000000000
RDX: 00000000000009f3 RSI: 00000000ffff8801 RDI: 0000000000004f99
RBP: ffff8801daf07348 R08: 0000000000000000 R09: 0000000000000000
R10: 0000780baf52484d R11: 0000000000000000 R12: 1ffff1003b5e0e5c
R13: 0000000000004f89 R14: dffffc0000000000 R15: 1ffff1003b5e0e58
FS:  00007f4ba8413700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000340 CR3: 00000001cf0ac000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 cgroup_account_cputime include/linux/cgroup.h:724 [inline]
 update_curr+0x389/0xc00 kernel/sched/fair.c:832
 enqueue_entity+0x40d/0x2130 kernel/sched/fair.c:4195
 enqueue_task_fair+0x22d/0x910 kernel/sched/fair.c:5408
 enqueue_task kernel/sched/core.c:751 [inline]
 activate_task+0x123/0x2e0 kernel/sched/core.c:770
 ttwu_activate kernel/sched/core.c:1659 [inline]
 ttwu_do_activate+0xd5/0x1f0 kernel/sched/core.c:1718
 ttwu_queue kernel/sched/core.c:1863 [inline]
 try_to_wake_up+0x948/0x12b0 kernel/sched/core.c:2076
 wake_up_process+0x10/0x20 kernel/sched/core.c:2149
 hrtimer_wakeup+0x48/0x60 kernel/time/hrtimer.c:1647
 __run_hrtimer kernel/time/hrtimer.c:1398 [inline]
 __hrtimer_run_queues+0x3eb/0x10c0 kernel/time/hrtimer.c:1460
 hrtimer_interrupt+0x2f3/0x750 kernel/time/hrtimer.c:1518
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0x165/0x730 arch/x86/kernel/apic/apic.c:1050
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:863
 </IRQ>
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
---[ end trace 63a513d0f55cc290 ]---
RIP: 0010:task_css include/linux/cgroup.h:477 [inline]
RIP: 0010:task_ca kernel/sched/cpuacct.c:43 [inline]
RIP: 0010:cpuacct_charge+0x1b8/0x5d0 kernel/sched/cpuacct.c:349
Code: 68 ff ff ff 85 c0 74 0d 80 3d 45 31 3c 08 00 0f 84 04 02 00 00 48 b8  
00 00 00 00 00 fc ff df 49 8d 7d 10 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f  
85 65 03 00 00 4d 8b 65 10 4d 85 e4 0f 84 0a 01 00
RSP: 0018:ffff8801daf072b0 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: ffff8801c72b40c0 RCX: 0000000000000000
RDX: 00000000000009f3 RSI: 00000000ffff8801 RDI: 0000000000004f99
RBP: ffff8801daf07348 R08: 0000000000000000 R09: 0000000000000000
R10: 0000780baf52484d R11: 0000000000000000 R12: 1ffff1003b5e0e5c
R13: 0000000000004f89 R14: dffffc0000000000 R15: 1ffff1003b5e0e58
FS:  00007f4ba8413700(0000) GS:ffff8801daf00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000340 CR3: 00000001cf0ac000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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