On Thu, Sep 20, 2018 at 11:51 PM, Christoph Hellwig <[email protected]> wrote:
> On Thu, Sep 20, 2018 at 12:08:28PM -0700, Max Filippov wrote:
>> I'm not familiar with the details of alloc_contig_range implementation, but
>> I don't see how gfp_mask is used to limit allocation to non-high memory.
>> So when alloc_contig_range gets start and end PFNs in high memory
>> (from the CMA region allocated in high memory) it just returns high memory
>> pages -- that's what I see.
>
> I can't see what prevents people from doing a CMA in high memory either,
> which is bad as except for arm non of the callers handles it completely
> (and that includes xtensa, more below).

So far it was useful and sufficient for us.

> xtensa is partially prepared for
> it as it can remap in dma_alloc, but it is missing handling in either
> the ->mmap or ->get_sgtable methods.

I'd rather implement the missing parts or put a WARN there if
implementing it is too hard or impossible than remove the existing
partial support.

-- 
Thanks.
-- Max
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