linux-kernel - Re: [PATCH v2] mm/slub: support left redzone

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Message-ID: <CAAmzW4MH3EmnXCmz-n=qYGPXZhrajVYOCkNw_0XvhnOK=T9-Ng@mail.gmail.com>
Date:	Sat, 27 Feb 2016 02:08:35 +0900
From:	Joonsoo Kim <js1304@...il.com>
To:	Andrey Ryabinin <ryabinin.a.a@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux.com>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v2] mm/slub: support left redzone

2016-02-27 1:47 GMT+09:00 Andrey Ryabinin <ryabinin.a.a@...il.com>:
> 2016-02-26 7:36 GMT+03:00  <js1304@...il.com>:
>> From: Joonsoo Kim <iamjoonsoo.kim@....com>
>>
>> SLUB already has a redzone debugging feature.  But it is only positioned
>> at the end of object (aka right redzone) so it cannot catch left oob.
>> Although current object's right redzone acts as left redzone of next
>> object, first object in a slab cannot take advantage of this effect.  This
>> patch explicitly adds a left red zone to each object to detect left oob
>> more precisely.
>>
>
> So why for each object? Can't we have left redzone only for the first object?

It's easier to implement and less code churn than allowing left redzone
only for the first object.

Thanks.