mm/memory: use kmap_local_page() in __wp_page_copy_user()

mm/memory: use kmap_local_page() in __wp_page_copy_user()

kmap_atomic() has been deprecated in favor of kmap_local_{folio,page}.

Therefore, replace kmap_atomic() with kmap_local_page in
__wp_page_copy_user().

kmap_atomic() disables preemption in !PREEMPT_RT kernels and
unconditionally disables also page-faults.  My limited knowledge of the
implementation of __wp_page_copy_user() makes me think that the latter
side effect is still needed here, but kmap_local_page() is implemented not
to disable page-faults.

So, in addition to the conversion to local mapping, add explicit
pagefault_disable() / pagefault_enable() between mapping and un-mapping.

Link: https://lkml.kernel.org/r/20231120142418.6977-1-fmdefrancesco@gmail.com
Signed-off-by: Fabio M. De Francesco <fabio.maria.de.francesco@linux.intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>