Re: [PATCH v2 1/2] mm, kasan: improve double-free detection

[Andrey Ryabinin]

On 05/09/2016 04:20 PM, Dmitry Vyukov wrote:
> On Mon, May 9, 2016 at 3:01 PM, Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> wrote:
>>
>>
>> On 05/09/2016 02:35 PM, Luruo, Kuthonuzo wrote:
>>>
>>> This patch with atomic bit op is similar in spirit to v1 except that it increases metadata size.
>>>
>>
>> I don't think that this is a big deal. That will slightly increase size of objects <= (128 - 32) bytes.
>> And if someone think otherwise, we can completely remove 'alloc_size'
>> (we use it only to print size in report - not very useful).
> 
> 
> Where did 128 come from?
> We now should allocate only 32 bytes for 16-byte user object. If not,
> there is something to fix.
> 

I just said this wrong. I mean that the patch increases size of objects that have object_size <= (128 - 32).
For bigger objects, the new 'struct kasan_[alloc,free]_meta' still fits into optimal redzone.