linux-kernel - Re: [PATCH 0/6] Boot-time switching between 4- and 5-level paging for 4.15, Part 1

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Message-ID: <20171020152346.f6tjybt7i5kzbhld@gmail.com>
Date:   Fri, 20 Oct 2017 17:23:46 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     "Kirill A. Shutemov" <kirill@...temov.name>,
        Ingo Molnar <mingo@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...capital.net>,
        Cyrill Gorcunov <gorcunov@...nvz.org>,
        Borislav Petkov <bp@...e.de>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/6] Boot-time switching between 4- and 5-level paging
 for 4.15, Part 1


* Kirill A. Shutemov <kirill.shutemov@...ux.intel.com> wrote:

> On Fri, Oct 20, 2017 at 08:18:53AM +0000, Ingo Molnar wrote:
> > 
> > * Kirill A. Shutemov <kirill@...temov.name> wrote:
> > 
> > > On Tue, Oct 03, 2017 at 11:27:54AM +0300, Kirill A. Shutemov wrote:
> > > > On Fri, Sep 29, 2017 at 05:08:15PM +0300, Kirill A. Shutemov wrote:
> > > > > The first bunch of patches that prepare kernel to boot-time switching
> > > > > between paging modes.
> > > > > 
> > > > > Please review and consider applying.
> > > > 
> > > > Ping?
> > > 
> > > Ingo, is there anything I can do to get review easier for you?
> > 
> > Yeah, what is the conclusion on the sub-discussion of patch #2:
> > 
> >   [PATCH 2/6] mm/zsmalloc: Prepare to variable MAX_PHYSMEM_BITS
> > 
> > ... do we want to skip it entirely and use the other 5 patches?
> 
> Yes, please. MAX_PHYSMEM_BITS not variable yet in this part of the series.
> 
> And I will post some version the patch in the next part, if it will be
> required.

Could we add TRULY_MAX_PHYSMEM_BITS (with a better name), to be used in places 
where memory footprint is not a big concern?

Or, could we keep MAX_PHYSMEM_BITS constant, and introduce a _different_ constant 
that is dynamic, and which could be used in the cases where the 5-level paging 
config causes too much memory footprint in the common 4-level paging case?

Thanks,

	Ingo