Use the range clearing primitive clear_user_pages() when clearing contiguous pages in clear_user_highpages(). We can safely do that when we have !CONFIG_HIGHMEM and when the architecture does not have clear_user_highpage. The first is necessary because not doing intermediate maps for pages lets contiguous page ranges stay contiguous. The second, because if the architecture has clear_user_highpage(), it likely needs flushing magic when clearing the page, magic that we aren't privy to. Signed-off-by: Ankur Arora --- Note: - reorganized based on the previous two patches. - Removed David's acked-by. include/linux/highmem.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 92aa1053c9c1..c6219700569f 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -278,11 +278,28 @@ static inline void clear_user_highpage(struct page *page, unsigned long vaddr) static inline void clear_user_highpages(struct page *page, unsigned long vaddr, unsigned int npages) { + +#if defined(clear_user_highpage) || defined(CONFIG_HIGHMEM) + /* + * An architecture defined clear_user_highpage() implies special + * handling is needed. + * + * So we use that or, the generic variant if CONFIG_HIGHMEM is + * enabled. + */ do { clear_user_highpage(page, vaddr); vaddr += PAGE_SIZE; page++; } while (--npages); +#else + + /* + * Prefer clear_user_pages() to allow for architectural optimizations + * when operating on contiguous page ranges. + */ + clear_user_pages(page_address(page), vaddr, page, npages); +#endif } #ifndef vma_alloc_zeroed_movable_folio -- 2.31.1