On Mon, Feb 23, 2015 at 01:40:25PM -0500, Matthew Wilcox wrote:

On Mon, Feb 23, 2015 at 12:29:45PM +0100, Arnd Bergmann wrote:

quoted

The DAX implementation relies on the architecture to provide a working
copy_user_page() function, as reported by Michael Ellerman's kisskb
build bot:

fs/dax.c: error: implicit declaration of function 'copy_user_page' [-Werror=implicit-function-declaration]:  => 266:2

We already have a list of architectures that are known to be incompatible,
but the list is missing ARC and SH at the moment. Further, blackfin and
c6x also lack support for this function, but are already excluded because
they do not support MMU-based kernels.

I've got a short list of patches for DAX; I'll add this one to the list.

Have the maintainers of these architectures been notified that they're
missing a core piece of kernel functionality?

Guess there a philosophical difference in opinion if the architecture code
should (have to) provide copy_user_page() or not outside the architecture
code itself. After all, fs/dax.c _is_ the only user of this function outside
the architecture code.

Guenter