Re: [PATCH] mm: migrate: fix an incorrect call of prep_transhuge_page()

[Andrew Morton]

On Mon, 20 Nov 2017 21:18:55 -0500 Zi Yan <zi.yan@xxxxxxxx> wrote:

> In [1], Andrea reported that during memory hotplug/hot remove
> prep_transhuge_page() is called incorrectly on non-THP pages for
> migration, when THP is on but THP migration is not enabled.
> This leads to a bad state of target pages for migration.
> 
> This patch fixes it by only calling prep_transhuge_page() when we are
> certain that the target page is THP.

What are the user-visible effects of the bug?