linux-kernel - Re: [PATCH v2 2/2] arm64/mm/kasan: don't use vmemmap

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Message-ID: <a1f63638-7edd-a498-d89f-67dea59a247a@virtuozzo.com>
Date:   Tue, 7 Nov 2017 19:24:38 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Pavel Tatashin <pasha.tatashin@...cle.com>, will.deacon@....com,
        mhocko@...nel.org, akpm@...ux-foundation.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org, x86@...nel.org,
        kasan-dev@...glegroups.com, borntraeger@...ibm.com,
        heiko.carstens@...ibm.com, willy@...radead.org,
        ard.biesheuvel@...aro.org, mark.rutland@....com,
        catalin.marinas@....com, sam@...nborg.org,
        mgorman@...hsingularity.net, steven.sistare@...cle.com,
        daniel.m.jordan@...cle.com, bob.picco@...cle.com
Subject: Re: [PATCH v2 2/2] arm64/mm/kasan: don't use vmemmap_populate() to
 initialize shadow

On 11/06/2017 09:35 PM, Pavel Tatashin wrote:
> From: Will Deacon <will.deacon@....com>
> 
> The kasan shadow is currently mapped using vmemmap_populate() since that
> provides a semi-convenient way to map pages into init_top_pgt. However,
> since that no longer zeroes the mapped pages, it is not suitable for kasan,
> which requires zeroed shadow memory.
> 
> Add kasan_populate_shadow() interface and use it instead of
> vmemmap_populate(). Besides, this allows us to take advantage of gigantic
> pages and use them to populate the shadow, which should save us some memory
> wasted on page tables and reduce TLB pressure.
> 
> Signed-off-by: Will Deacon <will.deacon@....com>
> Signed-off-by: Pavel Tatashin <pasha.tatashin@...cle.com>
> ---

Acked-by: Andrey Ryabinin <aryabinin@...tuozzo.com>