linux-kernel - Re: [PATCH] mm/thp: Make ARCH_ENABLE_SPLIT_PMD_PTLOCK dependent on PGTABLE

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Date:   Mon, 10 May 2021 12:10:07 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     Anshuman Khandual <anshuman.khandual@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>, linux-mm@...ck.org,
        akpm@...ux-foundation.org, Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/thp: Make ARCH_ENABLE_SPLIT_PMD_PTLOCK dependent on
 PGTABLE_LEVELS > 2

On Mon, May 10, 2021 at 03:36:29PM +0530, Anshuman Khandual wrote:
> 
> 
> On 5/10/21 2:23 PM, Peter Zijlstra wrote:
> > On Mon, May 10, 2021 at 10:05:45AM +0530, Anshuman Khandual wrote:
> >> -	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if X86_64 || X86_PAE
> >> +	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
> > 
> > It's still very early on a Monday, but IIRC this new condition is
> > identical to the pre-existing one.
> 
> Did not get it, could you please elaborate ?

When using x86_PAE, you must have more than two pgtable levels, right?
And not speaking of x86_64.

-- 
Oscar Salvador
SUSE L3