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Message-ID: <CAPAsAGwx7RGQyAv0xiBWnwnvn7Y3s0_VAM4bOTU8u66URibDmQ@mail.gmail.com>
Date: Sat, 31 Jan 2015 03:27:57 +0400
From: Andrey Ryabinin <ryabinin.a.a@...il.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andrey Ryabinin <a.ryabinin@...sung.com>,
LKML <linux-kernel@...r.kernel.org>,
Dmitry Vyukov <dvyukov@...gle.com>,
Konstantin Serebryany <kcc@...gle.com>,
Dmitry Chernenkov <dmitryc@...gle.com>,
Andrey Konovalov <adech.fo@...il.com>,
Yuri Gribov <tetra2005@...il.com>,
Konstantin Khlebnikov <koct9i@...il.com>,
Sasha Levin <sasha.levin@...cle.com>,
Christoph Lameter <cl@...ux.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Dave Hansen <dave.hansen@...el.com>,
Andi Kleen <andi@...stfloor.org>,
"x86@...nel.org" <x86@...nel.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, Jonathan Corbet <corbet@....net>,
Andy Lutomirski <luto@...capital.net>,
"open list:DOCUMENTATION" <linux-doc@...r.kernel.org>
Subject: Re: [PATCH v10 02/17] x86_64: add KASan support
2015-01-31 0:37 GMT+03:00 Andrew Morton <akpm@...ux-foundation.org>:
> On Fri, 30 Jan 2015 19:15:42 +0300 Andrey Ryabinin <a.ryabinin@...sung.com> wrote:
>
>> >> --- a/lib/Kconfig.kasan
>> >> +++ b/lib/Kconfig.kasan
>> >> @@ -5,6 +5,7 @@ if HAVE_ARCH_KASAN
>> >>
>> >> config KASAN
>> >> bool "AddressSanitizer: runtime memory debugger"
>> >> + depends on !MEMORY_HOTPLUG
>> >> help
>> >> Enables address sanitizer - runtime memory debugger,
>> >> designed to find out-of-bounds accesses and use-after-free bugs.
>> >
>> > That's a significant restriction. It has obvious runtime implications.
>> > It also means that `make allmodconfig' and `make allyesconfig' don't
>> > enable kasan, so compile coverage will be impacted.
>> >
>> > This wasn't changelogged. What's the reasoning and what has to be done
>> > to fix it?
>> >
>>
>> Yes, this is runtime dependency. Hot adding memory won't work.
>> Since we don't have shadow for hotplugged memory, kernel will crash on the first access to it.
>> To fix this we need to allocate shadow for new memory.
>>
>> Perhaps it would be better to have a runtime warning instead of Kconfig dependecy?
>
> Is there a plan to get mem-hotplug working with kasan, btw? It doesn't
> strike me as very important/urgent. Please add a sentence about this
> to the changelog as well.
>
I don't have a strict plan for this. I could work on this, but not now
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