Re: [GIT PULL] x86/mm changes for v5.9

From: Linus Torvalds
Date: Thu Aug 06 2020 - 15:03:05 EST

On Thu, Aug 6, 2020 at 11:57 AM Joerg Roedel <jroedel@xxxxxxx> wrote:
> On Thu, Aug 06, 2020 at 03:10:34PM +0200, Ingo Molnar wrote:
> >
> > * Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> > > So apparently the "the page-table pages are all pre-allocated now" is
> > > simply not true. Joerg?
> It pre-allocates the whole vmalloc/ioremap PUD/P4D pages, but I actually
> only tested it with 4-level paging, as I don't have access to 5-level
> paging hardware.

I don't think Jason has either.


PGD 0 P4D 0

line tells us that "pgd_present()" is true, even though PGD is 0
(otherwise it wouldn't print the P4D part). That means that he doesn't
have l5 enabled.

But you may obviously have different settings for CONFIG_X86_5LEVEL,
and maybe that ends up changing something?

But since apparently it's not immediately obvious what the problem is,
I'll revert it for now.