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From:   Andrey Konovalov <andreyknvl@google.com>
Date:   Thu, 12 Nov 2020 01:05:30 +0100
Message-ID: <CAAeHK+yf11KvZWkL1HCrxFT0R4VWH+Bz8YtnOYW7k6vm5c_h=A@mail.gmail.com>
Subject: Re: [PATCH v9 10/44] kasan: define KASAN_GRANULE_PAGE
To:     Marco Elver <elver@google.com>
Cc:     Alexander Potapenko <glider@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        kasan-dev <kasan-dev@googlegroups.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Wed, Nov 11, 2020 at 8:05 PM Marco Elver <elver@google.com> wrote:
>
> On Wed, 11 Nov 2020 at 19:48, Andrey Konovalov <andreyknvl@google.com> wrote:
> >
> > On Wed, Nov 11, 2020 at 3:13 PM Alexander Potapenko <glider@google.com> wrote:
> > >
> > > On Tue, Nov 10, 2020 at 11:11 PM Andrey Konovalov <andreyknvl@google.com> wrote:
> > > >
> > > > Define KASAN_GRANULE_PAGE as (KASAN_GRANULE_SIZE << PAGE_SHIFT), which is
> > > > the same as (KASAN_GRANULE_SIZE * PAGE_SIZE), and use it across KASAN code
> > > > to simplify it.
> > >
> > > What's the physical sense behind KASAN_GRANULE_PAGE? Is it something
> > > more than just a product of two constants?
> >
> > No, just a product.
> >
> > > The name suggests it might be something page-sized, but in reality it is not.
> >
> > What name would you prefer?
>
> Is it actually KASAN_GRANULES_PER_SHADOW_PAGE ?   AFAIK we're trying
> to calculate the granules that we can fit into a page of shadow
> memory.

Not exactly, it's the amount of memory, not the number of granules.

Will name it KASAN_MEMORY_PER_SHADOW_PAGE in v10.