FAILED: patch "[PATCH] mm/hugetlb: do not dissolve gigantic pages without runtime" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x a363c62a653cc8b3e21da9545fa4e028ef50f9c3
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026092905-mystified-upstart-3f7b@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From a363c62a653cc8b3e21da9545fa4e028ef50f9c3 Mon Sep 17 00:00:00 2001
From: Longlong Xia <xialonglong@kylinos.cn>
Date: Sun, 23 Aug 2026 12:40:51 +0800
Subject: [PATCH] mm/hugetlb: do not dissolve gigantic pages without runtime
 support

dissolve_free_hugetlb_folio() doesn't check
hstate_is_gigantic_no_runtime(h) though remove_hugetlb_folio()/
update_and_free_hugetlb_folio() silently bail for such folios, so it frees
a still-listed folio and, on vmemmap restore failure, the
add_hugetlb_folio() rollback corrupts the free list.

Link: https://lore.kernel.org/20260823044118.1097121-2-xialonglong2025@163.com
Fixes: 6eb4e88a6d27 ("hugetlb: create remove_hugetlb_page() to separate functionality")
Signed-off-by: Longlong Xia <xialonglong@kylinos.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Assisted-by: Codex:gpt-5.6-sol
Acked-by: Muchun Song <muchun.song@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 4f6f58bf3db6..d28972cd33f5 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1967,6 +1967,15 @@ int dissolve_free_hugetlb_folio(struct folio *folio)
 		struct hstate *h = folio_hstate(folio);
 		bool adjust_surplus = false;
 
+		/*
+		 * remove_hugetlb_folio()/update_and_free_hugetlb_folio() bail
+		 * for gigantic hstates without runtime support, so dissolving one
+		 * here would leave it on the free list and, on vmemmap restore
+		 * failure, the add_hugetlb_folio() rollback corrupts that list.
+		 */
+		if (hstate_is_gigantic_no_runtime(h))
+			goto out;
+
 		if (!available_huge_pages(h))
 			goto out;