linux-kernel - Re: [PATCH v3] kasan/quarantine: fix bugs on qlist_move

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Date:	Fri, 1 Jul 2016 16:20:53 +0200
From:	Dmitry Vyukov <dvyukov@...gle.com>
To:	Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:	Joonsoo Kim <js1304@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alexander Potapenko <glider@...gle.com>,
	kasan-dev <kasan-dev@...glegroups.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: Re: [PATCH v3] kasan/quarantine: fix bugs on qlist_move_cache()

On Fri, Jul 1, 2016 at 4:18 PM, Andrey Ryabinin <aryabinin@...tuozzo.com> wrote:
>
>
> On 07/01/2016 05:15 PM, Dmitry Vyukov wrote:
>> On Fri, Jul 1, 2016 at 4:09 PM, Joonsoo Kim <js1304@...il.com> wrote:
>>> 2016-07-01 23:03 GMT+09:00 Dmitry Vyukov <dvyukov@...gle.com>:
>
>>>>> +
>>>>> +               if (obj_cache == cache)
>>>>> +                       qlist_put(to, qlink, cache->size);
>>>>> +               else
>>>>> +                       qlist_put(from, qlink, cache->size);
>>>>
>>>> This line is wrong. If obj_cache != cache, object size != cache->size.
>>>> Quarantine contains objects of different sizes.
>>>
>>> You're right. 11 pm is not good time to work. :/
>>> If it is fixed, the patch looks correct to you?
>>> I will fix it and send v4 on next week.
>>
>>
>> I don't see anything else wrong. But I need to see how you fix the size issue.
>> Performance of this operation is not particularly critical, so the
>> simpler the better.
>
> Is there any other way besides obvious: s/cache->size/obj_cache->size ?

We can remember the original bytes, then subtract
num_objects_moved*cache->size from it and assign to from->bytes.