Re: [PATCH rfc 0/5] mm: introduce shrinker sysfs interface

[Kent Overstreet <kent.overstreet@gmail.com>]

On Fri, Apr 15, 2022 at 05:27:51PM -0700, Roman Gushchin wrote:
> 7) Don't display cgroups with less than 500 attached objects
>   $ echo 500 > count_memcg
>   $ cat count_memcg
>     53 817
>     1868 886
>     2396 799
>     2462 861
> 
> 8) Don't display cgroups with less than 500 attached objects (sum over all nodes)
>   $ echo "500" > count_memcg_node
>   $ cat count_memcg_node
>     53 810 7
>     1868 886 0
>     2396 799 0
>     2462 861 0
> 
> 9) Scan system/root shrinker
>   $ cat count
>     212
>   $ echo 100 > scan
>   $ cat scan
>     97
>   $ cat count
>     115

This part seems entirely overengineered though and a really bad idea - can we
please _not_ store query state in the kernel? It's not thread safe, and it seems
like overengineering before we've done the basics (just getting this stuff in
sysfs is a major improvement!).

I know kmemleak does something kinda sorta like this, but that's a special
purpose debugging tool and this looks to be something more general purpose
that'll get used in production.