From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 837E81A275 for ; Fri, 4 Sep 2026 00:13:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788480831; cv=none; b=LsbtiOTQ4Th7sKhWRRkxNDmWnC8LbWRoXNhhaZr0ttznqk0rajpaePSVtYnnfMmJBdvMhjT8j9A8S/9apN5iLkemUyChUQYhyDfxBoADWEMLD9UpQjOPx4ff/Umblxzql3wYuLM6ZB//rS3bz88gDP+cmGjXIZ3GDnFfRSewvh0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788480831; c=relaxed/simple; bh=x95x8ByBOFAbEhPbMoynMwIfot1LLa6QxB1HAMrVifA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uZao/L8TOdvC37ekbjGSOGGKsTjAUR3K8GyE0bwA9A+FfJA05Sv6Sn9kJkinrhcLqNXt6cvfwMAkV/mvUm5LFOapebWzM3QLT1sWBi7BAnHgEL7ADMIVlHEXggBuEYDi4ayLuavpBGNT1lZO96lIfbyYPnNUdngqzHAgGNGIU3w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ig4kunTe; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ig4kunTe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 327741F000E9; Fri, 4 Sep 2026 00:13:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788480827; bh=7DBfiZ/mzs5Y4vxsdsId7Pws4eD6+Orho8kwCtbtqT4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=ig4kunTedrKFqUzpVQErZIMFUSQiEJc5+EemQ7/kAISYly3NYkZFTtPUC11LgCiME sYGpdMMifXBKFrlVXGf8SZZGm4B0QmkjVVhAaddq5NIq2wsOd+JJBOUezfEBUxOBfg dXf0JC5owJxdYQlaW20AI3Ck/ZOsOnN1B9XIuqjxxqiS9iKNlZxjSMf3Zu7hAnqOYf pY3W4d71llbJ6ACWt5FW/6jwsK3tbV1p43OLJQoWs5SEsz3bZljIid8anMhFXj/etq XmCwg7Y9HzgI2OLyoBNwBKQmBVhYbo60BQV3hLMEZW2Q+DYjvCdA5vqywqKsnixWWb TqIYepO91csuw== From: Sasha Levin To: stable@vger.kernel.org Cc: Dev Jain , Muchun Song , "David Hildenbrand (Arm)" , Alistair Popple , Andi Kleen , Anshuman Khandual , Byungchul Park , Catalin Marinas , Dave Hansen , Gregory Price , Harry Yoo , "Huang, Ying" , Jann Horn , Josh Poimboeuf , Joshua Hahn , Kiryl Shutsemau , Lance Yang , "Liam R. Howlett" , Lorenzo Stoakes , Matthew Brost , Mel Gorman , Naoya Horiguchi , Oscar Salvador , Pedro Falcato , Rakie Kim , Ralph Campbell , Rik van Riel , Ryan Roberts , Vlastimil Babka , Will Deacon , Zi Yan , Andrew Morton , Sasha Levin Subject: [PATCH 6.18.y] mm/rmap: use huge_ptep_get() in try_to_migrate_one() Date: Thu, 3 Sep 2026 20:13:42 -0400 Message-ID: <20260904001342.2018975-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090357-moneybags-crewless-3b5f@gregkh> References: <2026090357-moneybags-crewless-3b5f@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Dev Jain [ Upstream commit 9be12ffa78cd087d41086f937a156435d4e588e9 ] try_to_migrate_one() is used by folio migration to replace a present mapping with a migration entry. For hugetlb folios, page_vma_mapped_walk() returns the pte pointer to the hugetlb folio in pvmw.pte, but the code reads the huge pte entry with ptep_get(). On arches which provide their own huge_ptep_get() to dereference a huge pte pointer, accessing via ptep_get() would cause pte_pfn(), pte_present() etc to misbehave. It is not clear whether this has a trivially visible effect to userspace. Use huge_ptep_get() to dereference a huge pte pointer. Commit a98a2f0c8ce1 copied the bug from try_to_unmap_one into try_to_migrate_one. [akpm@linux-foundation.org: coding-style cleanups] Link: https://lore.kernel.org/20260703114202.365553-4-dev.jain@arm.com Fixes: a98a2f0c8ce1 ("mm/rmap: split migration into its own function") Signed-off-by: Dev Jain Acked-by: Muchun Song Acked-by: David Hildenbrand (Arm) Cc: Alistair Popple Cc: Andi Kleen Cc: Anshuman Khandual Cc: Byungchul Park Cc: Catalin Marinas Cc: Dave Hansen Cc: Gregory Price Cc: Harry Yoo Cc: "Huang, Ying" Cc: Jann Horn Cc: Josh Poimboeuf Cc: Joshua Hahn Cc: Jun'ichi "Nick" Nomura Cc: Kiryl Shutsemau Cc: Lance Yang Cc: Liam R. Howlett Cc: Lorenzo Stoakes Cc: Matthew Brost Cc: Mel Gorman Cc: Naoya Horiguchi Cc: Oscar Salvador Cc: Pedro Falcato Cc: Rakie Kim Cc: Ralph Campbell Cc: Rik van Riel Cc: Ryan Roberts Cc: Vlastimil Babka Cc: Will Deacon Cc: Zi Yan Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- mm/rmap.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 4c78c71099093..399ffa7c19355 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2378,20 +2378,23 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, /* Unexpected PMD-mapped THP? */ VM_BUG_ON_FOLIO(!pvmw.pte, folio); - /* - * Handle PFN swap PTEs, such as device-exclusive ones, that - * actually map pages. - */ - pteval = ptep_get(pvmw.pte); + address = pvmw.address; + if (folio_test_hugetlb(folio)) + pteval = huge_ptep_get(mm, address, pvmw.pte); + else + pteval = ptep_get(pvmw.pte); if (likely(pte_present(pteval))) { pfn = pte_pfn(pteval); } else { + /* + * Handle PFN swap PTEs, such as device-exclusive ones, + * that actually map pages. + */ pfn = swp_offset_pfn(pte_to_swp_entry(pteval)); VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio); } subpage = folio_page(folio, pfn - folio_pfn(folio)); - address = pvmw.address; anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(subpage); -- 2.53.0