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In-Reply-To: <4abf8ddb-ff93-436f-a834-39e7f4d7a503@xen0n.name>
From:   Huacai Chen <chenhuacai@kernel.org>
Date:   Wed, 27 Sep 2023 08:45:24 +0800
Message-ID: <CAAhV-H5z5a45PobUQ5xU3rP6bqenoqtuuceX2=ijYhTN6a_vqg@mail.gmail.com>
Subject: Re: [PATCH] LoongArch: numa: Fix high_memory calculation
To:     WANG Xuerui <kernel@xen0n.name>
Cc:     Huacai Chen <chenhuacai@loongson.cn>,
        Arnd Bergmann <arnd@arndb.de>, loongarch@lists.linux.dev,
        linux-arch@vger.kernel.org, Xuefeng Li <lixuefeng@loongson.cn>,
        Guo Ren <guoren@kernel.org>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        linux-kernel@vger.kernel.org, loongson-kernel@lists.loongnix.cn,
        stable@vger.kernel.org, Chong Qiao <qiaochong@loongson.cn>
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On Tue, Sep 26, 2023 at 11:26=E2=80=AFPM WANG Xuerui <kernel@xen0n.name> wr=
ote:
>
> On 9/26/23 20:10, Huacai Chen wrote:
> > high_memory is the virtual address of the 'highest physical address' in
> > the system. But __va(get_num_physpages() << PAGE_SHIFT) is not what we
> > want because there may be holes in the physical address space. On the
> > other hand, max_low_pfn is calculated from memblock_end_of_DRAM(), whic=
h
> > is exactly corresponding to the highest physical address, so use it for
> > high_memory calculation.
> >
> > Cc: <stable@vger.kernel.org>
> Which commit is this patch intended to amend? A "Fixes:" tag may be
> helpful for stable backporting.
OK, I will add a Fixes: tag.

Huacai

> > Signed-off-by: Chong Qiao <qiaochong@loongson.cn>
> > Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
> > ---
> >   arch/loongarch/kernel/numa.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/loongarch/kernel/numa.c b/arch/loongarch/kernel/numa.=
c
> > index c7d33c489e04..6e65ff12d5c7 100644
> > --- a/arch/loongarch/kernel/numa.c
> > +++ b/arch/loongarch/kernel/numa.c
> > @@ -436,7 +436,7 @@ void __init paging_init(void)
> >
> >   void __init mem_init(void)
> >   {
> > -     high_memory =3D (void *) __va(get_num_physpages() << PAGE_SHIFT);
> > +     high_memory =3D (void *) __va(max_low_pfn << PAGE_SHIFT);
> >       memblock_free_all();
> >   }
> >
>
> --
> WANG "xen0n" Xuerui
>
> Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/
>