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Message-ID: <20190731161047.ypye54x5c5jje5sq@willie-the-truck>
Date: Wed, 31 Jul 2019 17:10:48 +0100
From: Will Deacon <will@...nel.org>
To: Anshuman Khandual <anshuman.khandual@....com>
Cc: linux-mm@...ck.org, Fenghua Yu <fenghua.yu@...el.com>,
Tony Luck <tony.luck@...el.com>, linux-ia64@...r.kernel.org,
Catalin Marinas <catalin.marinas@....com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Will Deacon <will.deacon@....com>, x86@...nel.org,
linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC 1/2] mm/sparsemem: Add vmem_altmap support in
vmemmap_populate_basepages()
On Fri, Jun 28, 2019 at 10:14:42AM +0530, Anshuman Khandual wrote:
> Generic vmemmap_populate_basepages() is used across platforms for vmemmap
> as standard or as fallback when huge pages mapping fails. On arm64 it is
> used for configs with ARM64_SWAPPER_USES_SECTION_MAPS applicable both for
> ARM64_16K_PAGES and ARM64_64K_PAGES which cannot use huge pages because of
> alignment requirements.
>
> This prevents those configs from allocating from device memory for vmemap
> mapping as vmemmap_populate_basepages() does not support vmem_altmap. This
> enables that required support. Each architecture should evaluate and decide
> on enabling device based base page allocation when appropriate. Hence this
> keeps it disabled for all architectures to preserve the existing semantics.
This commit message doesn't really make sense to me. There's a huge amount
of arm64-specific detail, followed by vague references to "this" and
"those" and "that" and I lost track of what you're trying to solve.
However, I puzzled through the code and I think it does make sense, so:
Acked-by: Will Deacon <will@...nel.org>
assuming you rewrite the commit message.
However, this has a dependency on your hot remove series which has open
comments from Mark Rutland afaict.
Will
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