Re: [RFC] x86/mm/dump_pagetables: Allow dumping pagetables by pid

[Dave Hansen]

On 8/4/22 00:04, lizhe.67@xxxxxxxxxxxxx wrote:
> In current kernel we can only dump a user task's pagetable
> by task itself. Sometimes we need to inspect the page table
> attributes of different memory maps to user space to meet
> the relevant development and debugging requirements. This
> patch helps us to make our works easier. It add two file
> named 'pid' and 'pid_pgtable_show'. We can use 'pid' to
> input the task we want to inspect and get pagetable info
> from 'pid_pgtable_show'.
> 
> User space can use file 'pid' and 'pid_pgtable_show' as follows.
> ====
> $ echo $pid > /sys/kernel/debug/page_tables/pid
> $ cat /sys/kernel/debug/page_tables/pid_pgtable_show

This seems a wee bit silly considering that we have /proc.  It's also
impossible to have an ABI like this work if multiple processes are
trying to dump different pids.

Are there any other per-process things in debugfs where folks have done
something similar?