linux-kernel - Re: [PATCH v2 0/7] SLAB support for KASAN

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Message-ID: <CAG_fn=WnLoM8SGDxa8Dvz62drPsh9_Mi_G_c2X-OENF_Oy8nFw@mail.gmail.com>
Date:	Thu, 18 Feb 2016 18:48:54 +0100
From:	Alexander Potapenko <glider@...gle.com>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Andrey Konovalov <adech.fo@...il.com>,
	Dmitriy Vyukov <dvyukov@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	JoonSoo Kim <js1304@...il.com>,
	Kostya Serebryany <kcc@...gle.com>, kasan-dev@...glegroups.com,
	LKML <linux-kernel@...r.kernel.org>,
	Linux Memory Management List <linux-mm@...ck.org>
Subject: Re: [PATCH v2 0/7] SLAB support for KASAN

Indeed, CONFIG_SLUB_DEBUG is not an issue by itself.

The biggest problem is the stack trace bookkeeping which currently
(with SLUB) requires 128 bytes for each allocation and deallocation
stack, bloating each memory object by 256 bytes.
If we make KASAN use the stack depot with SLUB we'll save a lot of memory.

On Thu, Feb 18, 2016 at 6:32 PM, Christoph Lameter <cl@...ux.com> wrote:
> On Thu, 18 Feb 2016, Alexander Potapenko wrote:
>
>> Unlike SLUB, SLAB doesn't store allocation/deallocation stacks for heap
>> objects, therefore we reimplement this feature in mm/kasan/stackdepot.c.
>> The intention is to ultimately switch SLUB to use this implementation as
>> well, which will remove the dependency on SLUB_DEBUG.
>
> This needs to be clarified a bit. CONFIG_SLUB_DEBUG is on by default. So
> the dependency does not matter much. I think you depend on the slowpath
> debug processing right? The issue is that you want to do these things in
> the fastpath?
>

-- 
Alexander Potapenko
Software Engineer

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