Re: [PATCH V2 2/2] mm/highmem: Lift memcpy_[to|from]_page to core

From: Matthew Wilcox
Date: Tue Dec 08 2020 - 07:24:16 EST


On Mon, Dec 07, 2020 at 02:57:03PM -0800, ira.weiny@xxxxxxxxx wrote:
> Placing these functions in 'highmem.h' is suboptimal especially with the
> changes being proposed in the functionality of kmap. From a caller
> perspective including/using 'highmem.h' implies that the functions
> defined in that header are only required when highmem is in use which is
> increasingly not the case with modern processors. Some headers like
> mm.h or string.h seem ok but don't really portray the functionality
> well. 'pagemap.h', on the other hand, makes sense and is already
> included in many of the places we want to convert.

pagemap.h is for the page cache. It's not for "random page
functionality". Yes, I know it's badly named. No, I don't want to
rename it. These helpers should go in highmem.h along with zero_user().