linux-kernel - Re: [PATCH v4 3/4] mm/pageblock: work around multiple arch's cmpxchg support issue

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Date:   Thu, 3 Sep 2020 00:29:16 -0700
From:   Max Filippov <jcmvbkbc@...il.com>
To:     Alex Shi <alex.shi@...ux.alibaba.com>
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        David Hildenbrand <david@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Alexander Duyck <alexander.duyck@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Russell King <linux@...linux.org.uk>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        "David S. Miller" <davem@...emloft.net>,
        Chris Zankel <chris@...kel.net>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org,
        "open list:SUPERH" <linux-sh@...r.kernel.org>,
        "open list:SPARC + UltraSPAR..." <sparclinux@...r.kernel.org>,
        "open list:TENSILICA XTENSA PORT (xtensa)" 
        <linux-xtensa@...ux-xtensa.org>,
        Linux Memory Management List <linux-mm@...ck.org>
Subject: Re: [PATCH v4 3/4] mm/pageblock: work around multiple arch's cmpxchg
 support issue

On Thu, Sep 3, 2020 at 12:01 AM Alex Shi <alex.shi@...ux.alibaba.com> wrote:
>
> Armv6, sh2, sparc32 and xtensa can not do cmpxchg1, so we have to use
> cmpxchg4 on it.

[...]

> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig> index e00d94b16658..03a6c7fd999d 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -48,6 +48,7 @@ config ARM
>         select GENERIC_ALLOCATOR
>         select GENERIC_ARCH_TOPOLOGY if ARM_CPU_TOPOLOGY
>         select GENERIC_ATOMIC64 if CPU_V7M || CPU_V6 || !CPU_32v6K || !AEABI
> +       select NO_CMPXCHG_BYTE if CPU_V6
>         select GENERIC_CLOCKEVENTS_BROADCAST if SMP
>         select GENERIC_CPU_AUTOPROBE
>         select GENERIC_EARLY_IOREMAP
> diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
> index d20927128fce..4c7f0ad5b93f 100644
> --- a/arch/sh/Kconfig
> +++ b/arch/sh/Kconfig
> @@ -155,6 +155,7 @@ menu "System type"
>  config CPU_SH2
>         bool
>         select SH_INTC
> +       select NO_CMPXCHG_BYTE
>
>  config CPU_SH2A
>         bool
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index efeff2c896a5..51ae5c8ede87 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -58,6 +58,7 @@ config SPARC32
>         select CLZ_TAB
>         select HAVE_UID16
>         select OLD_SIGACTION
> +       select NO_CMPXCHG_BYTE
>
>  config SPARC64
>         def_bool 64BIT
> diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
> index e997e0119c02..862b008ab09e 100644
> --- a/arch/xtensa/Kconfig
> +++ b/arch/xtensa/Kconfig
> @@ -42,6 +42,7 @@ config XTENSA
>         select MODULES_USE_ELF_RELA
>         select PERF_USE_VMALLOC
>         select VIRT_TO_BUS
> +       select NO_CMPXCHG_BYTE

Please keep the lists of select statements in Kconfig files above
alphabetically sorted.

-- 
Thanks.
-- Max