Re: [PATCH AUTOSEL 4.14 62/95] mm, memory_hotplug: initialize struct pages for the full memory section

From: Sasha Levin
Date: Tue May 07 2019 - 13:19:03 EST

On Tue, May 07, 2019 at 10:15:19AM -0700, Linus Torvalds wrote:
On Tue, May 7, 2019 at 10:02 AM Sasha Levin <sashal@xxxxxxxxxx> wrote:

I got it wrong then. I'll fix it up and get efad4e475c31 in instead.

Careful. That one had a bug too, and we have 891cb2a72d82 ("mm,
memory_hotplug: fix off-by-one in is_pageblock_removable").

All of these were *horribly* and subtly buggy, and might be
intertwined with other issues. And only trigger on a few specific
machines where the memory map layout is just right to trigger some
special case or other, and you have just the right config.

It might be best to verify with Michal Hocko. Michal?

Michal, is there a testcase I can plug into kselftests to make sure we
got this right (and don't regress)? We care a lot about memory hotplug
working right.