Commit 357b9276 authored by Kiryl Shutsemau's avatar Kiryl Shutsemau Committed by Andrew Morton
Browse files

mm/filemap: map entire large folio faultaround 

Currently, kernel only maps part of large folio that fits into
start_pgoff/end_pgoff range.

Map entire folio where possible.  It will match finish_fault() behaviour
that user hits on cold page cache.

Mapping large folios at once will allow the rmap code to mlock it on add,
as it will recognize that it is fully mapped and mlocking is safe.

Link: https://lkml.kernel.org/r/20250923110711.690639-6-kirill@shutemov.name


Signed-off-by: default avatarKiryl Shutsemau <kas@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 19773df0

mm/filemap.c

+15 −0
Original line number Diff line number Diff line
@@ -3670,6 +3670,21 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf, 
	struct page *page = folio_page(folio, start);

	unsigned int count = 0;

	pte_t *old_ptep = vmf->pte;

	unsigned long addr0;



	/*

	 * Map the large folio fully where possible.

	 *

	 * The folio must not cross VMA or page table boundary.

	 */

	addr0 = addr - start * PAGE_SIZE;

	if (folio_within_vma(folio, vmf->vma) &&

	    (addr0 & PMD_MASK) == ((addr0 + folio_size(folio) - 1) & PMD_MASK)) {

		vmf->pte -= start;

		page -= start;

		addr = addr0;

		nr_pages = folio_nr_pages(folio);

	}



	do {

		if (PageHWPoison(page + count))