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?