linux-kernel - Re: [PATCH V2] mm/thp: Define default pmd

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Message-ID: <2fde44aa-f74a-3948-d444-d04bc1f839eb@arm.com>
Date:   Thu, 10 Jun 2021 09:46:10 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     linux-mm@...ck.org, akpm@...ux-foundation.org,
        Nick Hu <nickhu@...estech.com>,
        Richard Henderson <rth@...ddle.net>,
        Vineet Gupta <vgupta@...opsys.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Guo Ren <guoren@...nel.org>,
        Brian Cain <bcain@...eaurora.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Michal Simek <monstr@...str.eu>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Ley Foon Tan <ley.foon.tan@...el.com>,
        Jonas Bonn <jonas@...thpole.se>,
        Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>,
        Stafford Horne <shorne@...il.com>,
        "James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        "David S. Miller" <davem@...emloft.net>,
        Jeff Dike <jdike@...toit.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Chris Zankel <chris@...kel.net>, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] mm/thp: Define default pmd_pgtable()



On 6/9/21 2:20 PM, Mike Rapoport wrote:
> Hi Anshuman,
> 
> On Wed, Jun 09, 2021 at 10:29:59AM +0530, Anshuman Khandual wrote:
>> Currently most platforms define pmd_pgtable() as pmd_page() duplicating the
>> same code all over. Instead just define a default value i.e pmd_page() for
>> pmd_pgtable() and let platforms override when required via <asm/pgtable.h>.
>> All the existing platform that override pmd_pgtable() have been moved into
>> their respective <asm/pgtable.h> header in order to precede before the new
>> generic definition. This makes it much cleaner with reduced code.
>>
>> Cc: Nick Hu <nickhu@...estech.com>
>> Cc: Richard Henderson <rth@...ddle.net>
>> Cc: Vineet Gupta <vgupta@...opsys.com>
>> Cc: Catalin Marinas <catalin.marinas@....com>
>> Cc: Will Deacon <will@...nel.org>
>> Cc: Guo Ren <guoren@...nel.org>
>> Cc: Brian Cain <bcain@...eaurora.org>
>> Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
>> Cc: Michal Simek <monstr@...str.eu>
>> Cc: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
>> Cc: Ley Foon Tan <ley.foon.tan@...el.com>
>> Cc: Jonas Bonn <jonas@...thpole.se>
>> Cc: Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>
>> Cc: Stafford Horne <shorne@...il.com>
>> Cc: "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>
>> Cc: Michael Ellerman <mpe@...erman.id.au>
>> Cc: Christophe Leroy <christophe.leroy@...roup.eu>
>> Cc: Paul Walmsley <paul.walmsley@...ive.com>
>> Cc: Palmer Dabbelt <palmer@...belt.com>
>> Cc: Heiko Carstens <hca@...ux.ibm.com>
>> Cc: Yoshinori Sato <ysato@...rs.sourceforge.jp>
>> Cc: "David S. Miller" <davem@...emloft.net>
>> Cc: Jeff Dike <jdike@...toit.com>
>> Cc: Thomas Gleixner <tglx@...utronix.de>
>> Cc: Chris Zankel <chris@...kel.net>
>> Cc: Andrew Morton <akpm@...ux-foundation.org>
>> Cc: linux-arch@...r.kernel.org
>> Cc: linux-mm@...ck.org
>> Cc: linux-kernel@...r.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> One nit below, otherwise
> 
> Acked-by: Mike Rapoport <rppt@...ux.ibm.com>
> 
>> ---
>> This patch applies on linux-next (20210608) as there is a merge conflict
>> dependency on the following commit.
>>
>> 40762590e8be ("mm: define default value for FIRST_USER_ADDRESS").
>>
>> This patch has been built tested across multiple platforms.
>>
>> Changes in V2:
>>
>> - Changed m68k per Geert
>>
>> Changes in V1:
>>
>> https://lore.kernel.org/linux-arch/1623130327-13325-1-git-send-email-anshuman.khandual@arm.com/
> ...
> 
>> diff --git a/arch/m68k/include/asm/sun3_pgalloc.h b/arch/m68k/include/asm/sun3_pgalloc.h
>> index 000f64869b91..198036aff519 100644
>> --- a/arch/m68k/include/asm/sun3_pgalloc.h
>> +++ b/arch/m68k/include/asm/sun3_pgalloc.h
>> @@ -32,7 +32,6 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, pgtable_t page
>>  {
>>  	pmd_val(*pmd) = __pa((unsigned long)page_address(page));
>>  }
>> -#define pmd_pgtable(pmd) pmd_page(pmd)
>>  
>>  /*
>>   * allocating and freeing a pmd is trivial: the 1-entry pmd is
>> diff --git a/arch/m68k/include/asm/sun3_pgtable.h b/arch/m68k/include/asm/sun3_pgtable.h
>> index 5b24283a0a42..127282bd8b96 100644
>> --- a/arch/m68k/include/asm/sun3_pgtable.h
>> +++ b/arch/m68k/include/asm/sun3_pgtable.h
>> @@ -96,6 +96,8 @@
>>  
>>  #ifndef __ASSEMBLY__
>>  
>> +#define pmd_pgtable(pmd) pmd_page(pmd)
>> +
> Is this one really needed? Won't the generic definition work instead?
> 

It should, sun3_defconfig builds without problem. Will drop pmd_pgtable() here.