[withdrawn] mm-khugepaged-count-small-vmas-towards-scan-limit.patch removed from -mm tree

[withdrawn] mm-khugepaged-count-small-vmas-towards-scan-limit.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/khugepaged: count small VMAs towards scan limit
has been removed from the -mm tree.  Its filename was
     mm-khugepaged-count-small-vmas-towards-scan-limit.patch

This patch was dropped because it was withdrawn

------------------------------------------------------
From: Shivank Garg <shivankg@amd.com>
Subject: mm/khugepaged: count small VMAs towards scan limit
Date: Sun, 18 Jan 2026 19:22:55 +0000

The khugepaged_scan_mm_slot() uses a 'progress' counter to limit the
amount of work performed and consists of three components:
1. Transitioning to a new mm (+1).
2. Skipping an unsuitable VMA (+1).
3. Scanning a PMD-sized range (+HPAGE_PMD_NR).

Consider a 1MB VMA sitting between two 2MB alignment boundaries:

     vma1       vma2   vma3
    +----------+------+----------+
    |2M        |1M    |2M        |
    +----------+------+----------+
               ^      ^
               start  end
               ^
          hstart,hend

In this case, for vma2:
  hstart = round_up(start, HPAGE_PMD_SIZE)  -> Next 2MB alignment
  hend   = round_down(end, HPAGE_PMD_SIZE) -> Prev 2MB alignment

Currently, since `hend <= hstart`, VMAs that are too small or unaligned to
contain a hugepage are skipped without incrementing 'progress'.  A process
containing a large number of such small VMAs will unfairly consume more
CPU cycles before yielding compared to a process with fewer, larger, or
aligned VMAs.

Fix this by incrementing progress when the `hend <= hstart` condition
is met.

Additionally, change 'progress' type to `unsigned int` to match both the
'pages' type and the function return value.

Link: https://lkml.kernel.org/r/20260118192253.9263-8-shivankg@amd.com
Signed-off-by: Shivank Garg <shivankg@amd.com>
Suggested-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/khugepaged.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/mm/khugepaged.c~mm-khugepaged-count-small-vmas-towards-scan-limit
+++ a/mm/khugepaged.c
@@ -2403,7 +2403,7 @@ static unsigned int khugepaged_scan_mm_s
 	struct mm_slot *slot;
 	struct mm_struct *mm;
 	struct vm_area_struct *vma;
-	int progress = 0;
+	unsigned int progress = 0;
 
 	VM_BUG_ON(!pages);
 	lockdep_assert_held(&khugepaged_mm_lock);
@@ -2447,7 +2447,8 @@ static unsigned int khugepaged_scan_mm_s
 		}
 		hstart = round_up(vma->vm_start, HPAGE_PMD_SIZE);
 		hend = round_down(vma->vm_end, HPAGE_PMD_SIZE);
-		if (khugepaged_scan.address > hend) {
+		if (khugepaged_scan.address > hend || hend <= hstart) {
+			/* VMA already scanned or too small/unaligned for hugepage. */
 			progress++;
 			continue;
 		}
_

Patches currently in -mm which might be from shivankg@amd.com are

mm-khugepaged-map-dirty-writeback-pages-failures-to-eagain.patch
mm-khugepaged-retry-with-sync-writeback-for-madv_collapse.patch
mm-khugepaged-remove-unnecessary-goto-skip-label.patch
mm-khugepaged-change-collapse_pte_mapped_thp-to-return-void.patch
mm-khugepaged-use-enum-scan_result-for-result-variables-and-return-types.patch
mm-khugepaged-make-khugepaged_collapse_control-static.patch