Commit 8c49fbaf authored by Kiryl Shutsemau's avatar Kiryl Shutsemau Committed by Andrew Morton
Browse files

mm/rmap: mlock large folios in try_to_unmap_one() 

Currently, try_to_unmap_once() only tries to mlock small folios.

Use logic similar to folio_referenced_one() to mlock large folios: only do
this for fully mapped folios and under page table lock that protects all
page table entries.

[akpm@linux-foundation.org: s/CROSSSED/CROSSED/]
Link: https://lkml.kernel.org/r/20250923110711.690639-4-kirill@shutemov.name


Signed-off-by: default avatarKiryl Shutsemau <kas@kernel.org>
Reviewed-by: default avatarShakeel Butt <shakeel.butt@linux.dev>
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>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent a2880202

mm/rmap.c

+28 −3
Original line number Diff line number Diff line
@@ -1870,6 +1870,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, 
	unsigned long nr_pages = 1, end_addr;

	unsigned long pfn;

	unsigned long hsz = 0;

	int ptes = 0;



	/*

	 * When racing against e.g. zap_pte_range() on another cpu,
@@ -1910,10 +1911,34 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, 
		 */

		if (!(flags & TTU_IGNORE_MLOCK) &&

		    (vma->vm_flags & VM_LOCKED)) {

			ptes++;



			/*

			 * Set 'ret' to indicate the page cannot be unmapped.

			 *

			 * Do not jump to walk_abort immediately as additional

			 * iteration might be required to detect fully mapped

			 * folio an mlock it.

			 */

			ret = false;



			/* Only mlock fully mapped pages */

			if (pvmw.pte && ptes != pvmw.nr_pages)

				continue;



			/*

			 * All PTEs must be protected by page table lock in

			 * order to mlock the page.

			 *

			 * If page table boundary has been cross, current ptl

			 * only protect part of ptes.

			 */

			if (pvmw.flags & PVMW_PGTABLE_CROSSED)

				goto walk_done;



			/* Restore the mlock which got missed */

			if (!folio_test_large(folio))

			mlock_vma_folio(folio, vma);

			goto walk_abort;

			goto walk_done;

		}



		if (!pvmw.pte) {