Re: [PATCH v5 2/7] mm, devm_memremap_pages: Kill mapping "System RAM" support

[Dan Williams]

On Fri, Sep 14, 2018 at 6:14 AM, Christoph Hellwig <hch@xxxxxx> wrote:
> On Wed, Sep 12, 2018 at 07:22:11PM -0700, Dan Williams wrote:
>> Given the fact that devm_memremap_pages() requires a percpu_ref that is
>> torn down by devm_memremap_pages_release() the current support for
>> mapping RAM is broken.
>
> I agree.  Do you remember why we even added it in the first place?

It was initially a copy over from memremap() that catches these
attempts and returns a direct-map pointer.