mm: allow a NULL fn callback in apply_to_page_range

Besides calling the callback on each page, apply_to_page_range also has
the effect of pre-faulting all PTEs for the range.  To support callers
that only need the pre-faulting, make the callback optional.

Based on a patch from Minchan Kim <[email protected]>.

Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Matthew Auld <[email protected]>
Cc: "Matthew Wilcox (Oracle)" <[email protected]>
Cc: Nitin Gupta <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: Uladzislau Rezki (Sony) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions