[Crash-utility] list cgroup from crash

[HAGIO KAZUHITO(萩尾 一仁)]

On 2023/08/28 15:39, Mathew T wrote:
> Hi,
> I am trying to figure out if I can extract the values associated with
> cgroups from kernel crash dump. I can see "cgorup" is mounted when i
> issue "mount" command in crash utility. And it shows mount/superblock
> address. How can I further dig down and print the values inside cgroup
> fs. Suppose if I want to print "/sys/fs/cgroup/cpu.stat" in the crash
> utility!? The extension lscgroup / cgget are not working in latest
> kernels.

As far as I know, there is no extension module that can print it with 
the recent cgroup implementation.

Also, cgroup fs is a pseudo one.  When you read a file in the fs, the 
kernel gathers information and prints it.  So you need to (1) find out 
what is done by reading the file and (2) emulate it with crash commands.

I'm not familiar with cgroup, but maybe it's good to start with 
cpu_stat_show() in kernel/cgroup/cgroup.c.

Thanks,
Kazu