+ mm-rmap-mlock-large-folios-in-try_to_unmap_one.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/rmap: mlock large folios in try_to_unmap_one()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-rmap-mlock-large-folios-in-try_to_unmap_one.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-rmap-mlock-large-folios-in-try_to_unmap_one.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Kiryl Shutsemau <kas@kernel.org>
Subject: mm/rmap: mlock large folios in try_to_unmap_one()
Date: Fri, 19 Sep 2025 13:40:34 +0100

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.

Link: https://lkml.kernel.org/r/20250919124036.455709-4-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau <kas@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/rmap.c |   23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

--- a/mm/rmap.c~mm-rmap-mlock-large-folios-in-try_to_unmap_one
+++ a/mm/rmap.c
@@ -1870,6 +1870,7 @@ static bool try_to_unmap_one(struct foli
 	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 +1911,26 @@ static bool try_to_unmap_one(struct foli
 		 */
 		if (!(flags & TTU_IGNORE_MLOCK) &&
 		    (vma->vm_flags & VM_LOCKED)) {
+			ptes++;
+			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_CROSSSED)
+				goto walk_done;
+
 			/* Restore the mlock which got missed */
-			if (!folio_test_large(folio))
-				mlock_vma_folio(folio, vma);
-			goto walk_abort;
+			mlock_vma_folio(folio, vma);
+			goto walk_done;
 		}
 
 		if (!pvmw.pte) {
_

Patches currently in -mm which might be from kas@kernel.org are

mm-khugepaged-do-not-fail-collapse_pte_mapped_thp-on-scan_pmd_null.patch
mm-page_vma_mapped-track-if-the-page-is-mapped-across-page-table-boundary.patch
mm-rmap-fix-a-mlock-race-condition-in-folio_referenced_one.patch
mm-rmap-mlock-large-folios-in-try_to_unmap_one.patch
mm-fault-try-to-map-the-entire-file-folio-in-finish_fault.patch
mm-rmap-improve-mlock-tracking-for-large-folios.patch