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 9AB0F3DAAB7; Fri, 4 Sep 2026 05:07:27 +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=1788498450; cv=none; b=E5yVhZInlOj4hBZVs3Hkax8JIBG32HZPCJRV0Fkcl2oS1uJ91NMfs8lepuvniuW3n6Ro1S1xGU69FU6s5qNya2CtCMlm+CHrCwHOA6XFjCniXx8hWWEIlqb24mNOewNqdgLjznmRp0bTlkx8sW5FW1B43CUJLooyu8kmk4k+rDY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788498450; c=relaxed/simple; bh=YW81rcT6EqePAXv63L7hMwELG6WUhHMO+l74NSwsM/s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JJU8fKWKA2Ap28ch+GZ9VRjF40oFLaTp5KhQYRWQieblShdrkPqQ6Sv6LSRhyXdwznHmhiFKVm3k2kcb5q3eGn8XeNxuo+W7O9y88OxLRe44wvnwa9lNHapTXMXdfbl2f746a0HS+z9T0cWxSTUHEDzkyy2iwwgtPUf0hHhu6es= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=sRseEyjI; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="sRseEyjI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D25DD1F00A3E; Fri, 4 Sep 2026 05:07:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788498447; bh=/zy7V2+jXAj7j8YDCH7VtUimubsJJQFXyjuaxrQNPsA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=sRseEyjImVD/VP4ro4fC+eSbr2G4xlZ1shBJoSi4Fe76o6Fn13shza6IQYOA4VlDI ExnLXlfwYBRL5lTkChypgzMJlPmseLpMpmmV4zEyhGTtaD7tWVUq4Pr4hUGC9jau0s s+FmKclpn5EZCyLMeuZqdQ2z61mRZhbJrUkJ/gdY= 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 Subject: [PATCH 7.2 065/713] mm/rmap: use huge_ptep_get() in try_to_migrate_one() Date: Fri, 4 Sep 2026 06:50:33 +0200 Message-ID: <20260904045805.297897815@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045803.810145556@linuxfoundation.org> References: <20260904045803.810145556@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dev Jain commit 9be12ffa78cd087d41086f937a156435d4e588e9 upstream. 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: Greg Kroah-Hartman --- mm/rmap.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2505,14 +2505,18 @@ static bool try_to_migrate_one(struct fo /* 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. + */ const softleaf_t entry = softleaf_from_pte(pteval); pfn = softleaf_to_pfn(entry); @@ -2520,7 +2524,6 @@ static bool try_to_migrate_one(struct fo } subpage = folio_page(folio, pfn - folio_pfn(folio)); - address = pvmw.address; anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(subpage);