From: Barry Song (Xiaomi) <baohua@kernel.org>
Date: Thu, 23 Apr 2026 03:49:17 +0000 (+0800)
Subject: mm/huge_memory: fix outdated comment about freeing subpages in __folio_split
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=085a7acf732f6040fd36b002e6a49c90b76db41c;p=thirdparty%2Flinux.git

mm/huge_memory: fix outdated comment about freeing subpages in __folio_split

The comment appears to be outdated.  add_to_swap() no longer exists,
and the explanation of why we need to call put_page() after splitting
could be made more general.

Link: https://lore.kernel.org/20260423034917.8234-1-baohua@kernel.org
Signed-off-by: Barry Song (Xiaomi) <baohua@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Youngjun Park <youngjun.park@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 970e077019b7..4586f3ccb133 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -4190,11 +4190,10 @@ fail:
 
 		folio_unlock(new_folio);
 		/*
-		 * Subpages may be freed if there wasn't any mapping
-		 * like if add_to_swap() is running on a lru page that
-		 * had its mapping zapped. And freeing these pages
-		 * requires taking the lru_lock so we do the put_page
-		 * of the tail pages after the split is complete.
+		 * Subpages whose mapping has been zapped may be freed
+		 * earlier, but freeing them requires taking the
+		 * lru_lock, so we defer put_page() on tail pages until
+		 * after the split completes.
 		 */
 		free_folio_and_swap_cache(new_folio);
 	}