linux-kernel - Re: [RFC V2] mm: Enable generic pfn_valid() to handle early sections with memmap holes

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Message-ID: <YIFKDm0FMARKvP9B@kernel.org>
Date:   Thu, 22 Apr 2021 13:03:58 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     David Hildenbrand <david@...hat.com>
Cc:     Anshuman Khandual <anshuman.khandual@....com>, linux-mm@...ck.org,
        akpm@...ux-foundation.org,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC V2] mm: Enable generic pfn_valid() to handle early sections
 with memmap holes

On Thu, Apr 22, 2021 at 11:48:58AM +0200, David Hildenbrand wrote:
> > 
> > > IOW, avoiding having to adjust generic pfn_valid()/pfn_to_online_page() at
> > > all. Am i missing something or should that be possible?
> > 
> > We are back again to the question "should arm64 free its memmap".
> > If the answer is no, we don't need arm64::pfn_valid() for SPARSEMEM at all.
> > If the answer is yes, Anshuman's patch is way better than a custom
> > pfn_valid().
> 
> Well, I propose something in between: stop freeing with SPARSEMEM, continue
> freeing with FLATMEM.

I'm all for it.

-- 
Sincerely yours,
Mike.