linux-kernel - Re: [PATCH v3 11/13] kmemleak: disable kasan instrumentation for kmemleak

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Date:	Fri, 26 Sep 2014 21:36:54 +0400
From:	Andrey Ryabinin <ryabinin.a.a@...il.com>
To:	Dmitry Vyukov <dvyukov@...gle.com>
Cc:	Andrey Ryabinin <a.ryabinin@...sung.com>,
	LKML <linux-kernel@...r.kernel.org>,
	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>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dave Hansen <dave.hansen@...el.com>,
	Andi Kleen <andi@...stfloor.org>,
	Vegard Nossum <vegard.nossum@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>, Dave Jones <davej@...hat.com>,
	x86@...nel.org, "linux-mm@...ck.org" <linux-mm@...ck.org>,
	Catalin Marinas <catalin.marinas@....com>
Subject: Re: [PATCH v3 11/13] kmemleak: disable kasan instrumentation for kmemleak

2014-09-26 21:10 GMT+04:00 Dmitry Vyukov <dvyukov@...gle.com>:
> Looks good to me.
>
> We can disable kasan instrumentation of this file as well.
>

Yes, but why? I don't think we need that.

> On Wed, Sep 24, 2014 at 5:44 AM, Andrey Ryabinin <a.ryabinin@...sung.com> wrote:
>> kmalloc internally round up allocation size, and kmemleak
>> uses rounded up size as object's size. This makes kasan
>> to complain while kmemleak scans memory or calculates of object's
>> checksum. The simplest solution here is to disable kasan.
>>
>> Signed-off-by: Andrey Ryabinin <a.ryabinin@...sung.com>
>> ---
>>  mm/kmemleak.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
>> index 3cda50c..9bda1b3 100644
>> --- a/mm/kmemleak.c
>> +++ b/mm/kmemleak.c
>> @@ -98,6 +98,7 @@
>>  #include <asm/processor.h>
>>  #include <linux/atomic.h>
>>
>> +#include <linux/kasan.h>
>>  #include <linux/kmemcheck.h>
>>  #include <linux/kmemleak.h>
>>  #include <linux/memory_hotplug.h>
>> @@ -1113,7 +1114,10 @@ static bool update_checksum(struct kmemleak_object *object)
>>         if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
>>                 return false;
>>
>> +       kasan_disable_local();
>>         object->checksum = crc32(0, (void *)object->pointer, object->size);
>> +       kasan_enable_local();
>> +
>>         return object->checksum != old_csum;
>>  }
>>
>> @@ -1164,7 +1168,9 @@ static void scan_block(void *_start, void *_end,
>>                                                   BYTES_PER_POINTER))
>>                         continue;
>>
>> +               kasan_disable_local();
>>                 pointer = *ptr;
>> +               kasan_enable_local();
>>
>>                 object = find_and_get_object(pointer, 1);
>>                 if (!object)
>> --
>> 2.1.1
>>
>


-- 
Best regards,
Andrey Ryabinin
--
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