On 02/12/2018 10:09 PM, Laura Abbott wrote:
> On 02/12/2018 11:21 AM, Alexey Skidanov wrote:
>> On 02/12/2018 08:30 PM, Laura Abbott wrote:
>>> On 02/10/2018 01:43 AM, Alexey Skidanov wrote:
>>>> Hi,
>>>> Current ion kernel mapping implementation uses vmap() to map previously
>>>> allocated buffers into kernel virtual address space. On 32 bit
>>>> platforms, vmap() might fail on large enough buffers due to the limited
>>>> available vmalloc space.
>>>> dma_buf_kmap() should guarantee that only one page is mapped at a time.
>>>> So, probably it's better to implement dma_buf_kmap() by kmap() and not
>>>> by vmap()?
>>>> Thanks,
>>>> Alexey
>>> The short answer is yes.
>>> The long answer is that the conversion to the dma_buf APIs kept the
>>> existing Ion behavior which mapped the entire buffer. We got away
>>> with this because the in kernel mapping APIs are used very infrequently
>>> and with buffers that never triggered an exhaustion of vmalloc
>>> space.
>>> If we actually start seeing problems with this we can fix it up
>>> but I don't consider this a high priority item.
>> I have the patch fixing this potential bug. I would like to submit it
>> for review, if you are ok with it. Please, just let me know.
> Yes, please submit from review and we can go from there.
Ok. Will submit it.
>>> Thanks,
>>> Laura
>> Thanks,
>> Alexey
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