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Date: Fri, 17 Jul 2015 16:13:07 +0300
From: Andrey Ryabinin <a.ryabinin@samsung.com>
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To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>, David Keitel <dkeitel@codeaurora.org>,
        Will Deacon <will.deacon@arm.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 5/5] arm64: add KASan support
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On 07/16/2015 07:03 PM, Catalin Marinas wrote:
> On Thu, Jul 16, 2015 at 06:30:11PM +0300, Andrey Ryabinin wrote:
>>
>> I think this may work, if pud_none(*pud) will be replaced with !pud_val(*pud).
>> We can't use pud_none() because with 2-level page tables it's always false, so
>> we will never go down to pmd level where swapper_pg_dir populated.
> 
> The reason I used "do ... while" vs "while" or "for" is so that it gets
> down to the pmd level. The iteration over pgd is always done in the top
> loop via pgd_addr_end while the loops for missing levels (nopud, nopmd)
> are always a single iteration whether we check for pud_none or not. But
> when the level is present, we avoid looping when !pud_none().
> 

Right, dunno what I was thinking.
It seems to work. Lightly tested with every possible CONFIG_PGTABLE_LEVELS.
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