Re: [v4] mm: khugepaged: avoid overriding min_free_kbytes set by user

From: Michal Hocko
Date: Thu Sep 17 2020 - 05:43:50 EST

On Wed 16-09-20 23:39:39, Vijay Balakrishna wrote:
> set_recommended_min_free_kbytes need to honor min_free_kbytes set by the
> user. Post start-of-day THP enable or memory hotplug operations can
> lose user specified min_free_kbytes, in particular when it is higher than
> calculated recommended value.

I was about to recommend a more detailed explanation when I have
realized that this patch is not really needed after all. Unless I am
missing something.

init_per_zone_wmark_min ignores the newly calculated min_free_kbytes if
it is lower than user_min_free_kbytes. So calculated min_free_kbytes >=

Except for value clamping when the value is reduced and this likely
needs fixing. But set_recommended_min_free_kbytes should be fine.
Michal Hocko