Re: [Linux 5.18-rc1] WARNING: CPU: 1 PID: 0 at kernel/sched/fair.c:3355 update_blocked_averages

[Ammar Faizi]

On 4/6/22 7:21 PM, Dietmar Eggemann wrote:
> On 05/04/2022 15:13, Ammar Faizi wrote:
> > On 4/5/22 7:21 PM, Dietmar Eggemann wrote:
> > > Tried to recreate the issue but no success so far. I used you config
> > > file, clang-14 and a Xeon CPU E5-2690 v2 (2 sockets 40 CPUs) with 20
> > > two-level cgoupv1 taskgroups '/X/Y' with 'hackbench (10 groups, 40 fds)
> > > + idling' running in all '/X/Y/'.
> > >
> > > What userspace are you running?
> >
> > HP Laptop, Intel i7-1165G7, 8 CPUs, with 16 GB of RAM. Ubuntu 21.10.
> > Just for
> > daily workstation. Compiling kernel, browsing and coding stuff.
>
> Can you check that CFS Bandwidth control (CONFIG_CFS_BANDWIDTH=y) is
> still not used on Ubuntu desktop 21.10?
>
> It shouldn't but I can't verify since I'm still on 20.04 LTS Desktop:
>
> $ mount | grep "cgroup2\|\bcpu\b"
> cgroup2 on /sys/fs/cgroup/unified type cgroup2 (rw,nosuid,nodev,noexec,relatime,nsdelegate)
> cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct)
>
> CPU controller is still used in cgroupv1. So cgroupv2 can't use it:
>
> $ cat /sys/fs/cgroup/unified/cgroup.controllers
> /* empty */
>
> And there is no cgroupv1 hierarchy under /sys/fs/cgroup/cpu,cpuacct/ .
>
> No cpu.cfs_quota_us files with something other than -1.
>
> So CFS Bandwidth control is not used.

Not familiar with CFS stuff, but here...

===============
ammarfaizi2@integral2:~$ mount | grep "cgroup2\|\bcpu\b"
cgroup2 on /sys/fs/cgroup type cgroup2 (rw,nosuid,nodev,noexec,relatime,nsdelegate,memory_recursiveprot)
ammarfaizi2@integral2:~$ cat /sys/fs/cgroup/unified/cgroup.controllers
cat: /sys/fs/cgroup/unified/cgroup.controllers: No such file or directory
ammarfaizi2@integral2:~$ ls /sys/fs/cgroup/{cpu,cpuacct}
ls: cannot access '/sys/fs/cgroup/cpu': No such file or directory
ls: cannot access '/sys/fs/cgroup/cpuacct': No such file or directory
ammarfaizi2@integral2:~$
ammarfaizi2@integral2:~$ cat /etc/os-release
PRETTY_NAME="Ubuntu 21.10"
NAME="Ubuntu"
VERSION_ID="21.10"
VERSION="21.10 (Impish Indri)"
VERSION_CODENAME=impish
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/";
SUPPORT_URL="https://help.ubuntu.com/";
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/";
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy";
UBUNTU_CODENAME=impish
ammarfaizi2@integral2:~$
===============

Update:
So far I have been using and torturing my machine for a day, but
still couldn't reproduce the issue. It seems I hit a rarely
happened bug. I will continue using this until 5.18-rc2 before
recompile my kernel.

--
Ammar Faizi