+ mm-huge_memory-optimize-old_order-derivation-during-folio-splitting.patch added to mm-new branch

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

The patch titled
     Subject: mm/huge_memory: Optimize old_order derivation during folio splitting
has been added to the -mm mm-new branch.  Its filename is
     mm-huge_memory-optimize-old_order-derivation-during-folio-splitting.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-huge_memory-optimize-old_order-derivation-during-folio-splitting.patch

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

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patches, and acceptance into mm-new is a notification for others take
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------------------------------------------------------
From: Wei Yang <richard.weiyang@gmail.com>
Subject: mm/huge_memory: Optimize old_order derivation during folio splitting
Date: Tue, 14 Oct 2025 13:46:05 +0000

Folio splitting requires both the folio's original order (@old_order) and
the new target order (@split_order).

In the current implementation, @old_order is repeatedly retrieved using
folio_order().

However, for every iteration after the first, the folio being split is the
result of the previous split, meaning its order is already known to be
equal to the previous iteration's @split_order.

This commit optimizes the logic:

  * Instead of calling folio_order(), we now set @old_order directly to
    the value of @split_order from the previous iteration.

  * The initial @split_order (which was previously handled by a separate
    @start_order variable) is now directly used, and the redundant
    @start_order variable is removed.

This change avoids unnecessary function calls and simplifies the loop
setup.

Link: https://lkml.kernel.org/r/20251014134606.22543-5-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/huge_memory.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/mm/huge_memory.c~mm-huge_memory-optimize-old_order-derivation-during-folio-splitting
+++ a/mm/huge_memory.c
@@ -3528,8 +3528,7 @@ static int __split_unmapped_folio(struct
 		struct address_space *mapping, bool uniform_split)
 {
 	bool is_anon = folio_test_anon(folio);
-	int order = folio_order(folio);
-	int start_order = uniform_split ? new_order : order - 1;
+	int old_order = folio_order(folio);
 	int split_order;
 
 	folio_clear_has_hwpoisoned(folio);
@@ -3538,10 +3537,9 @@ static int __split_unmapped_folio(struct
 	 * split to new_order one order at a time. For uniform split,
 	 * folio is split to new_order directly.
 	 */
-	for (split_order = start_order;
+	for (split_order = uniform_split ? new_order : old_order - 1;
 	     split_order >= new_order;
 	     split_order--) {
-		int old_order = folio_order(folio);
 		int new_folios = 1UL << (old_order - split_order);
 
 		/* order-1 anonymous folio is not supported */
@@ -3576,6 +3574,7 @@ static int __split_unmapped_folio(struct
 			mod_mthp_stat(split_order, MTHP_STAT_NR_ANON, new_folios);
 		}
 		folio = page_folio(split_at);
+		old_order = split_order;
 	}
 
 	return 0;
_

Patches currently in -mm which might be from richard.weiyang@gmail.com are

mm-compaction-check-the-range-to-pageblock_pfn_to_page-is-within-the-zone-first.patch
mm-compaction-fix-the-range-to-pageblock_pfn_to_page.patch
mm-huge_memory-add-pmd-folio-to-ds_queue-in-do_huge_zero_wp_pmd.patch
mm-khugepaged-unify-pmd-folio-installation-with-map_anon_folio_pmd.patch
mm-huge_memory-only-get-folio_order-once-during-__folio_split.patch
mm-huge_memory-cache-folio-attribute-in-__split_unmapped_folio.patch
mm-huge_memory-update-folio-stat-after-successful-split.patch
mm-huge_memory-optimize-and-simplify-folio-stat-update-after-split.patch
mm-huge_memory-optimize-old_order-derivation-during-folio-splitting.patch
mm-huge_memory-remove-redundant-split_order-=-new_order-check-in-uniform_split.patch