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

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Date:   Thu, 6 Aug 2020 23:20:19 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Joerg Roedel <jroedel@...e.de>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [GIT PULL] x86/mm changes for v5.9


* Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> On Thu, Aug 6, 2020 at 11:57 AM Joerg Roedel <jroedel@...e.de> wrote:
> >
> > On Thu, Aug 06, 2020 at 03:10:34PM +0200, Ingo Molnar wrote:
> > >
> > > * Linus Torvalds <torvalds@...ux-foundation.org> 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.
> 
> The
> 
>         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.

I've reverted it in x86/urgent as well earlier today, can send you 
that tree right now if you prefer that route.

Thanks,

	Ingo