From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: js1304@gmail.com, Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
kasan-dev@googlegroups.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
kernel-team@lge.com, Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH v1 00/11] mm/kasan: support per-page shadow memory to reduce memory consumption
Date: Wed, 17 May 2017 15:17:13 +0300 [thread overview]
Message-ID: <ebcc02d9-fa2b-30b1-2260-99cdf7434487@virtuozzo.com> (raw)
In-Reply-To: <1494897409-14408-1-git-send-email-iamjoonsoo.kim@lge.com>
On 05/16/2017 04:16 AM, js1304@gmail.com wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> Hello, all.
>
> This is an attempt to recude memory consumption of KASAN. Please see
> following description to get the more information.
>
> 1. What is per-page shadow memory
>
> This patch introduces infrastructure to support per-page shadow memory.
> Per-page shadow memory is the same with original shadow memory except
> the granualarity. It's one byte shows the shadow value for the page.
> The purpose of introducing this new shadow memory is to save memory
> consumption.
>
> 2. Problem of current approach
>
> Until now, KASAN needs shadow memory for all the range of the memory
> so the amount of statically allocated memory is so large. It causes
> the problem that KASAN cannot run on the system with hard memory
> constraint. Even if KASAN can run, large memory consumption due to
> KASAN changes behaviour of the workload so we cannot validate
> the moment that we want to check.
>
> 3. How does this patch fix the problem
>
> This patch tries to fix the problem by reducing memory consumption for
> the shadow memory. There are two observations.
>
I think that the best way to deal with your problem is to increase shadow scale size.
You'll need to add tunable to gcc to control shadow size. I expect that gcc has some
places where 8-shadow scale size is hardcoded, but it should be fixable.
The kernel also have some small amount of code written with KASAN_SHADOW_SCALE_SIZE == 8 in mind,
which should be easy to fix.
Note that bigger shadow scale size requires bigger alignment of allocated memory and variables.
However, according to comments in gcc/asan.c gcc already aligns stack and global variables and at
32-bytes boundary.
So we could bump shadow scale up to 32 without increasing current stack consumption.
On a small machine (1Gb) 1/32 of shadow is just 32Mb which is comparable to yours 30Mb, but I expect it to be
much faster. More importantly, this will require only small amount of simple changes in code, which will be
a *lot* more easier to maintain.
I'd start from implementing this on the kernel side only. With KASAN_OUTLINE and disabled
stack instrumentation (--param asan-stack=0) it's doable without any changes in gcc.
...
> base vs patched
>
> MemTotal: 858 MB vs 987 MB
> runtime: 0 MB vs 30MB
> Net Available: 858 MB vs 957 MB
>
> For 4096 MB QEMU system
>
> MemTotal: 3477 MB vs 4000 MB
> runtime: 0 MB vs 50MB
>
> base vs patched (2048 MB QEMU system)
> 204 s vs 224 s
> Net Available: 3477 MB vs 3950 MB
>
> Thanks.
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next prev parent reply other threads:[~2017-05-17 12:15 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-16 1:16 [PATCH v1 00/11] mm/kasan: support per-page shadow memory to reduce memory consumption js1304
2017-05-16 1:16 ` [PATCH v1 01/11] mm/kasan: rename XXX_is_zero to XXX_is_nonzero js1304
2017-05-16 1:16 ` [PATCH v1 02/11] mm/kasan: don't fetch the next shadow value speculartively js1304
2017-05-16 1:16 ` [PATCH v1 03/11] mm/kasan: handle unaligned end address in zero_pte_populate js1304
2017-05-16 1:16 ` [PATCH v1 04/11] mm/kasan: extend kasan_populate_zero_shadow() js1304
2017-05-16 1:16 ` [PATCH v1 05/11] mm/kasan: introduce per-page shadow memory infrastructure js1304
2017-05-16 1:16 ` [PATCH v1 06/11] mm/kasan: mark/unmark the target range that is for original shadow memory js1304
2017-05-16 1:16 ` [PATCH v1 07/11] x86/kasan: use per-page " js1304
2017-05-16 1:16 ` [PATCH v1 08/11] mm/kasan: support on-demand shadow allocation/mapping js1304
2017-05-16 1:16 ` [PATCH v1 09/11] x86/kasan: support on-demand shadow mapping js1304
2017-05-16 1:16 ` [PATCH v1 10/11] mm/kasan: support dynamic shadow memory free js1304
2017-05-16 1:16 ` [PATCH v1 11/11] mm/kasan: change the order of shadow memory check js1304
2017-05-16 1:28 ` [PATCH(RE-RESEND) v1 01/11] mm/kasan: rename _is_zero to _is_nonzero Joonsoo Kim
2017-05-16 4:34 ` [PATCH v1 00/11] mm/kasan: support per-page shadow memory to reduce memory consumption Dmitry Vyukov
2017-05-16 4:47 ` Dmitry Vyukov
2017-05-16 6:23 ` Joonsoo Kim
2017-05-16 20:49 ` Dmitry Vyukov
2017-05-17 7:23 ` Joonsoo Kim
2017-05-17 7:25 ` Joonsoo Kim
2017-05-24 6:57 ` Dmitry Vyukov
2017-05-24 7:45 ` Joonsoo Kim
2017-05-24 17:19 ` Dmitry Vyukov
2017-05-25 0:41 ` Joonsoo Kim
2017-05-29 15:07 ` Dmitry Vyukov
2017-05-29 15:12 ` Dmitry Vyukov
2017-05-29 15:29 ` Dmitry Vyukov
2017-05-30 7:58 ` Vladimir Murzin
2017-05-30 8:15 ` Dmitry Vyukov
2017-05-30 8:31 ` Vladimir Murzin
2017-05-30 8:40 ` Vladimir Murzin
2017-05-30 8:49 ` Dmitry Vyukov
2017-05-30 9:08 ` Vladimir Murzin
2017-05-30 9:26 ` Dmitry Vyukov
2017-05-30 9:39 ` Vladimir Murzin
2017-05-30 9:45 ` Dmitry Vyukov
2017-05-30 9:54 ` Vladimir Murzin
2017-05-30 14:16 ` Andrey Ryabinin
2017-05-31 5:50 ` Joonsoo Kim
2017-05-31 16:31 ` Andrey Ryabinin
2017-06-08 2:43 ` Joonsoo Kim
2017-06-01 15:16 ` 王靖天
2017-06-01 18:06 ` Dmitry Vyukov
2017-06-08 2:40 ` Joonsoo Kim
2017-06-13 16:49 ` Andrey Ryabinin
2017-06-14 0:12 ` Joonsoo Kim
2017-05-17 12:17 ` Andrey Ryabinin [this message]
2017-05-19 1:53 ` Joonsoo Kim
2017-05-22 6:02 ` Dmitry Vyukov
2017-05-24 6:04 ` Joonsoo Kim
2017-05-24 16:31 ` Dmitry Vyukov
2017-05-25 0:46 ` Joonsoo Kim
2017-05-22 14:00 ` Andrey Ryabinin
2017-05-24 6:18 ` Joonsoo Kim
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