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Date: Wed, 27 Jun 2018 18:11:38 -0700
From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v4 00/17] khwasan: kernel hardware assisted address
 sanitizer
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To: Vishwath Mohan <vishwath@google.com>
Cc: Kostya Serebryany <kcc@google.com>, andreyknvl@google.com, aryabinin@virtuozzo.com, Alexander Potapenko <glider@google.com>, Dmitry Vyukov <dvyukov@google.com>, catalin.marinas@arm.com, will.deacon@arm.com, cl@linux.com, mark.rutland@arm.com, Nick Desaulniers <ndesaulniers@google.com>, marc.zyngier@arm.com, dave.martin@arm.com, ard.biesheuvel@linaro.org, ebiederm@xmission.com, mingo@kernel.org, Paul Lawrence <paullawrence@google.com>, geert@linux-m68k.org, arnd@arndb.de, kirill.shutemov@linux.intel.com, gregkh@linuxfoundation.org, kstewart@linuxfoundation.org, rppt@linux.vnet.ibm.com, kasan-dev@googlegroups.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sparse@vger.kernel.org, linux-mm@kvack.org, linux-kbuild@vger.kernel.org, Evgenii Stepanov <eugenis@google.com>, Lee.Smith@arm.com, Ramana.Radhakrishnan@arm.com, Jacob.Bramley@arm.com, Ruben.Ayrapetyan@arm.com, Jann Horn <jannh@google.com>, Mark Brand <markbrand@google.com>, cpandya@codeaurora.org

On Wed, 27 Jun 2018 17:59:00 -0700 Vishwath Mohan <vishwath@google.com> wrote:

> > > > time consume much less memory, trading that off for somewhat imprecise
> > > > bug detection and being supported only for arm64.
> > >
> > > Why do we consider this to be a worthwhile change?
> > >
> > > Is KASAN's memory consumption actually a significant problem?  Some
> > > data regarding that would be very useful.
> >
> > On mobile, ASAN's and KASAN's memory usage is a significant problem.
> > Not sure if I can find scientific evidence of that.
> > CC-ing Vishwath Mohan who deals with KASAN on Android to provide
> > anecdotal evidence.
> >
> Yeah, I can confirm that it's an issue. Like Kostya mentioned, I don't have
> data on-hand, but anecdotally both ASAN and KASAN have proven problematic
> to enable for environments that don't tolerate the increased memory
> pressure well. This includes,
> (a) Low-memory form factors - Wear, TV, Things, lower-tier phones like Go
> (c) Connected components like Pixel's visual core
> <https://www.blog.google/products/pixel/pixel-visual-core-image-processing-and-machine-learning-pixel-2/>
> 
> 
> These are both places I'd love to have a low(er) memory footprint option at
> my disposal.

Thanks.

It really is important that such information be captured in the
changelogs.  In as much detail as can be mustered.