+ mm-memory-failure-fix-refcount-leak-on-soft-offline-lbs-folio.patch added to mm-new branch

The patch titled
     Subject: mm/memory-failure: fix refcount leak on soft-offline LBS folio
has been added to the -mm mm-new branch.  Its filename is
     mm-memory-failure-fix-refcount-leak-on-soft-offline-lbs-folio.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-memory-failure-fix-refcount-leak-on-soft-offline-lbs-folio.patch

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

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: liyouhong <[email protected]>
Subject: mm/memory-failure: fix refcount leak on soft-offline LBS folio
Date: Mon, 3 Aug 2026 14:00:01 +0800

soft_offline_in_use_page() runs with a folio reference taken by
get_hwpoison_page() (or by the caller when MF_COUNT_INCREASED is set, e.g.
madvise(MADV_SOFT_OFFLINE)).

made soft-offline skip splitting when min_order_for_split() is non-zero,
so large-block-size folios stay intact.  That early return -EBUSY path
never drops the reference.

The other failure path is fine: try_to_split_thp_page(..., release=true)
puts the page when the split itself fails.  memory_failure() also puts
explicitly on its analogous unsplit path.

Split the new_order != 0 case out and folio_put() before returning.

Link: https://lore.kernel.org/[email protected]
Fixes: 689b8986776c ("mm/memory-failure: improve large block size folio handling")
Signed-off-by: liyouhong <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 mm/memory-failure.c |   14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

--- a/mm/memory-failure.c~mm-memory-failure-fix-refcount-leak-on-soft-offline-lbs-folio
+++ a/mm/memory-failure.c
@@ -2870,9 +2870,19 @@ static int soft_offline_in_use_page(stru
 		 * NOTE: if minimizing the number of soft offline pages is
 		 * preferred, split it to non-zero new_order like it is done in
 		 * memory_failure().
+		 *
+		 * Drop the ref from get_hwpoison_page()/MF_COUNT_INCREASED;
+		 * try_to_split_thp_page(..., release=true) does that itself
+		 * when the split fails.
 		 */
-		if (new_order || try_to_split_thp_page(page, /* new_order= */ 0,
-						       /* release= */ true)) {
+		if (new_order) {
+			pr_info("%#lx: order-%d folio cannot soft offline\n",
+				pfn, new_order);
+			folio_put(folio);
+			return -EBUSY;
+		}
+		if (try_to_split_thp_page(page, /* new_order= */ 0,
+					 /* release= */ true)) {
 			pr_info("%#lx: thp split failed\n", pfn);
 			return -EBUSY;
 		}
_

Patches currently in -mm which might be from [email protected] are

mm-damon-ops-common-putback-folios-on-invalid-migrate-nid.patch
mm-memory-failure-fix-refcount-leak-on-soft-offline-lbs-folio.patch