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. > > Thanks, > Laura
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