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Message-ID: <4abf8ddb-ff93-436f-a834-39e7f4d7a503@xen0n.name>
Date:   Tue, 26 Sep 2023 23:26:30 +0800
MIME-Version: 1.0
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Subject: Re: [PATCH] LoongArch: numa: Fix high_memory calculation
To:     Huacai Chen <chenhuacai@loongson.cn>,
        Arnd Bergmann <arnd@arndb.de>,
        Huacai Chen <chenhuacai@kernel.org>
Cc:     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>
References: <20230926121031.1901760-1-chenhuacai@loongson.cn>
Content-Language: en-US
From:   WANG Xuerui <kernel@xen0n.name>
In-Reply-To: <20230926121031.1901760-1-chenhuacai@loongson.cn>
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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(), which
> 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.
> 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 = (void *) __va(get_num_physpages() << PAGE_SHIFT);
> +	high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
>   	memblock_free_all();
>   }
>   

-- 
WANG "xen0n" Xuerui

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