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Subject: Re: [RFC] arm64: mm: update max_pfn after memory hotplug
To:     Chris Goldsworthy <quic_cgoldswo@quicinc.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org,
        Sudarshan Rajagopalan <quic_sudaraja@quicinc.com>
References: <cover.1632437225.git.quic_cgoldswo@quicinc.com>
 <595d09279824faf1f54961cef52b745609b05d97.1632437225.git.quic_cgoldswo@quicinc.com>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
Message-ID: <833493d2-d585-47ee-c258-79eae5deff36@redhat.com>
Date:   Mon, 27 Sep 2021 17:51:41 +0200
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On 24.09.21 00:54, Chris Goldsworthy wrote:
> From: Sudarshan Rajagopalan <quic_sudaraja@quicinc.com>
> 
> After new memory blocks have been hotplugged, max_pfn and max_low_pfn
> needs updating to reflect on new PFNs being hot added to system.
> 
> Signed-off-by: Sudarshan Rajagopalan <quic_sudaraja@quicinc.com>
> Signed-off-by: Chris Goldsworthy <quic_cgoldswo@quicinc.com>
> ---
>   arch/arm64/mm/mmu.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index cfd9deb..fd85b51 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1499,6 +1499,11 @@ int arch_add_memory(int nid, u64 start, u64 size,
>   	if (ret)
>   		__remove_pgd_mapping(swapper_pg_dir,
>   				     __phys_to_virt(start), size);
> +	else {
> +		max_pfn = PFN_UP(start + size);
> +		max_low_pfn = max_pfn;
> +	}
> +
>   	return ret;

Note: didn't verify if updating max_low_pfn is correct here.

Acked-by: David Hildenbrand <david@redhat.com>


-- 
Thanks,

David / dhildenb