linux-kernel - [PATCH v1 02/12] mm/rmap: reject hugetlb folios in folio_make_device

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250129115411.2077152-3-david@redhat.com>
Date: Wed, 29 Jan 2025 12:54:00 +0100
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-doc@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	linux-mm@...ck.org,
	nouveau@...ts.freedesktop.org,
	David Hildenbrand <david@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jérôme Glisse <jglisse@...hat.com>,
	Jonathan Corbet <corbet@....net>,
	Alex Shi <alexs@...nel.org>,
	Yanteng Si <si.yanteng@...ux.dev>,
	Karol Herbst <kherbst@...hat.com>,
	Lyude Paul <lyude@...hat.com>,
	Danilo Krummrich <dakr@...nel.org>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Jann Horn <jannh@...gle.com>,
	Pasha Tatashin <pasha.tatashin@...een.com>,
	Peter Xu <peterx@...hat.com>,
	Alistair Popple <apopple@...dia.com>,
	Jason Gunthorpe <jgg@...dia.com>,
	stable@...r.kernel.org
Subject: [PATCH v1 02/12] mm/rmap: reject hugetlb folios in folio_make_device_exclusive()

Even though FOLL_SPLIT_PMD on hugetlb now always fails with -EOPNOTSUPP,
let's add a safety net in case FOLL_SPLIT_PMD usage would ever be reworked.

In particular, before commit 9cb28da54643 ("mm/gup: handle hugetlb in the
generic follow_page_mask code"), GUP(FOLL_SPLIT_PMD) would just have
returned a page. In particular, hugetlb folios that are not PMD-sized
would never have been prone to FOLL_SPLIT_PMD.

hugetlb folios can be anonymous, and page_make_device_exclusive_one() is
not really prepared for handling them at all. So let's spell that out.

Fixes: b756a3b5e7ea ("mm: device exclusive memory access")
Cc: <stable@...r.kernel.org>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 mm/rmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index c6c4d4ea29a7..17fbfa61f7ef 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -2499,7 +2499,7 @@ static bool folio_make_device_exclusive(struct folio *folio,
 	 * Restrict to anonymous folios for now to avoid potential writeback
 	 * issues.
 	 */
-	if (!folio_test_anon(folio))
+	if (!folio_test_anon(folio) || folio_test_hugetlb(folio))
 		return false;
 
 	rmap_walk(folio, &rwc);
-- 
2.48.1