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Subject: Re: [PATCH v12 01/14] ARM: mm: add missing pud_page define to 2-level
 page tables
From:   Ding Tianhong <dingtianhong@huawei.com>
To:     Russell King - ARM Linux admin <linux@armlinux.org.uk>,
        Nicholas Piggin <npiggin@gmail.com>
CC:     <linux-mm@kvack.org>, Andrew Morton <akpm@linux-foundation.org>,
        <linux-kernel@vger.kernel.org>, <linux-arch@vger.kernel.org>,
        <linuxppc-dev@lists.ozlabs.org>,
        Jonathan Cameron <Jonathan.Cameron@Huawei.com>,
        Christoph Hellwig <hch@infradead.org>,
        Christophe Leroy <christophe.leroy@csgroup.eu>,
        Rick Edgecombe <rick.p.edgecombe@intel.com>,
        <linux-arm-kernel@lists.infradead.org>
References: <20210202110515.3575274-1-npiggin@gmail.com>
 <20210202110515.3575274-2-npiggin@gmail.com>
 <20210202111319.GL1463@shell.armlinux.org.uk>
 <d1f661f2-f473-1dd8-94cc-fe76714249b5@huawei.com>
Message-ID: <a9773c79-4fa3-dd26-27f3-bbd88600db1b@huawei.com>
Date:   Tue, 2 Feb 2021 19:48:13 +0800
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On 2021/2/2 19:47, Ding Tianhong wrote:
> On 2021/2/2 19:13, Russell King - ARM Linux admin wrote:
>> On Tue, Feb 02, 2021 at 09:05:02PM +1000, Nicholas Piggin wrote:
>>> diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
>>> index c02f24400369..d63a5bb6bd0c 100644
>>> --- a/arch/arm/include/asm/pgtable.h
>>> +++ b/arch/arm/include/asm/pgtable.h
>>> @@ -166,6 +166,9 @@ extern struct page *empty_zero_page;
>>>  
>>>  extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
>>>  
>>> +#define pud_page(pud)		pmd_page(__pmd(pud_val(pud)))
>>> +#define pud_write(pud)		pmd_write(__pmd(pud_val(pud)))
>>
>> As there is no PUD, does it really make sense to return a valid
>> struct page (which will be the PTE page) for pud_page(), which is
>> several tables above?
>>
> --- a/arch/arm/include/asm/pgtable-2level.h
> +++ b/arch/arm/include/asm/pgtable-2level.h
> 
> +static inline int pud_none(pud_t pud)
> +{
> +          return 0;
> +}
> 
 --- a/arch/arm/include/asm/pgtable-2level.h
 +++ b/arch/arm/include/asm/pgtable-2level.h>
 +static inline int pud_page(pud_t pud)
 +{
 +          return 0;
 +}

> I think it could be fix like this.
> 
> Ding
>