From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794061377; b=Q5+qtSIZHOe/O80EaG64AscUbdjV+j7ohSHOBb08Pk1YrAsFY8dDgYNaN9/yJC0TzOcu 4B0UPUE59bz6UoyBgbuZ5rrsNcY365iNC2rvu+HBs8T4/dJMuOS4qGz4rSIBuWfYZzPWa bigJf0GPQC9dQ6muzCE0L9jZUd1K8j/A8q2Q07NyUb4vJOApAqXU2I99a2AuTNxeA2AoW 6gj7+jHsKMoN+Hlp5NmCATQfSsCuM1wMwxUUhp3qAOZrDSqYnrmYdwxASw/apm6ryyKqK JfziCNBr/iK/dDcBtBIKeHGOlO9uBZtZj2ARbkztaZHx+rDAvPDmUKCpm17wUi4Hssg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794061377; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=xEJ4wCmePQA4D6ht4IHRz3GXsa9NmkfcQS4QnceH7pI=; b=dyuQc5lkN3EbDWsilPqKcM8Q5kKrPdgKjcKRvnJdAL+nRJ90z2NuTcaBfSy5s7R01E/7 Y5U9bg/J+KKShuF2Yke6vr+IUD0006kKAd1eYx2Me+W0dNcClGzo1OaeeW+8HBZEFrfOT Hb9Ga4g8w4JTO7FUegk+cVesAfRdlP11hAmvw3xvBXU3uzMrLdRWDrmE9NONDPoWMDr1W +AML0S+VHcDUg1iuvbEWv67MwBszx5ccYdJhZz0tFtT7NLttr9qgG7a7FhXJNLsC4Khnu H4Hf584hGn4lCsOP/1Bcydu8T6gfXaehjt2IB/cT80O0VXP297RB3Ft2NCu/28G0xKg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=fSSBaYg+; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C282B606A337; Sat, 7 Nov 2026 14:22:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=fSSBaYg+ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5575A1F008A7; Sat, 7 Nov 2026 14:22:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794061376; bh=xEJ4wCmePQA4D6ht4IHRz3GXsa9NmkfcQS4QnceH7pI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fSSBaYg+dUDlYSu/qAywlVZ7eiFHWQqUiBAogkJAgi+KBKcNudMstdc5AiQw86fZ4 5/coOrov5R6L7Ec4gglAAFYhwaoc/TDYffhTwIbUoSEtSskVacvjVZd+t4rkQMnqLz zg9e5bSv1sj+9ARvMS7ptlbzMUPeHmPDAgQ4Cu2w= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, 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 , =?UTF-8?q?Junichi=20 Nick =20Nomura?= , 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 6.12 0461/1536] mm/rmap: use huge_ptep_get() in try_to_migrate_one() Date: Sat, 7 Nov 2026 08:41:17 -0500 Message-ID: <20261107135010.468815967@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107134957.653319350@linuxfoundation.org> References: <20261107134957.653319350@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ 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 [ sashal: Kept the tree's existing pfn/zone-device code and added only the hugetlb huge_ptep_get() read, skipping the upstream softleaf and pteval rewrite. ] Signed-off-by: Sasha Levin --- mm/rmap.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index bc9c66cc950b7..d165050c2fc56 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2109,7 +2109,11 @@ 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); - pfn = pte_pfn(ptep_get(pvmw.pte)); + address = pvmw.address; + if (folio_test_hugetlb(folio)) + pfn = pte_pfn(huge_ptep_get(mm, address, pvmw.pte)); + else + pfn = pte_pfn(ptep_get(pvmw.pte)); if (folio_is_zone_device(folio)) { /* @@ -2127,7 +2131,6 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, } else { subpage = folio_page(folio, pfn - folio_pfn(folio)); } - address = pvmw.address; anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(subpage); -- 2.53.0