linux-kernel - Re: [PATCH v2 12/13] um: add support for folded p4d page tables

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Message-Id: <20191101101432.7998A2086D@mail.kernel.org>
Date:   Fri, 01 Nov 2019 11:14:28 +0100
From:   rppt@...nel.org
To:     Richard Weinberger <richard@....at>
CC:     linux-mm <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        anton ivanov <anton.ivanov@...bridgegreys.com>,
        Arnd Bergmann <arnd@...db.de>, davem <davem@...emloft.net>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Greentime Hu <green.hu@...il.com>,
        Greg Ungerer <gerg@...ux-m68k.org>,
        Helge Deller <deller@....de>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Jeff Dike <jdike@...toit.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        torvalds <torvalds@...ux-foundation.org>,
        Mark Salter <msalter@...hat.com>,
        Matt Turner <mattst88@...il.com>,
        Michal Simek <monstr@...str.eu>, Peter Rosin <peda@...ntia.se>,
        Rolf Eike Beer <eike-kernel@...tec.de>,
        Russell King <linux@...linux.org.uk>,
        Sam Creasey <sammy@...my.net>,
        Vincent Chen <deanbo422@...il.com>,
        Vineet Gupta <Vineet.Gupta1@...opsys.com>,
        linux-alpha <linux-alpha@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-c6x-dev@...r.kernel.org
Subject: Re: [PATCH v2 12/13] um: add support for folded p4d page tables

<linux-c6x-dev@...ux-c6x.org>,linux-kernel <linux-kernel@...r.kernel.org>,linux-m68k <linux-m68k@...ts.linux-m68k.org>,linux-parisc <linux-parisc@...r.kernel.org>,linux-um <linux-um@...ts.infradead.org>,sparclinux <sparclinux@...r.kernel.org>,Mike Rapoport <rppt@...ux.ibm.com>
From: Mike Rapoport <rppt@...nel.org>
Message-ID: <E5D8BD4D-5286-427C-A347-D73AC26EC256@...nel.org>

On November 1, 2019 10:20:09 AM GMT+01:00, Richard Weinberger <richard@....at> wrote:
>----- Ursprüngliche Mail -----
>> Von: "Mike Rapoport" <rppt@...nel.org>
>
>[...]
>
>> #define pte_page(x) pfn_to_page(pte_pfn(x))
>> diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
>> index 417ff64..6fd17bc 100644
>> --- a/arch/um/kernel/mem.c
>> +++ b/arch/um/kernel/mem.c
>> @@ -92,10 +92,26 @@ static void __init one_md_table_init(pud_t *pud)
>> #endif
>> }
>> 
>> +static void __init one_pud_table_init(p4d_t *p4d)
>> +{
>> +#if CONFIG_PGTABLE_LEVELS > 3
>
>Isn't this dead code?
>
>For uml we have:
>config PGTABLE_LEVELS
>        int
>        default 3 if 3_LEVEL_PGTABLES
>        default 2

It's kinda a provision for 4 levels support in UML :)
I can drop this in the next respin, no problem.

>Thanks,
>//richard


-- 
Sincerely yours,
Mike