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 E9B2F383C6E for ; Thu, 3 Sep 2026 23:56:41 +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=1788479808; cv=none; b=YcEwjBvkhI8QK6apYzJSUwAtNHxI7LJ3U4+vuWPOhCBLbA3wMV5HLDaL0VelEjhKQ7719/G9Y971VMu44DjJcSdYTm/XmiMXOhktzO1hxIDqxpiCZHO3L38S8ilz+Ek3u0SOG+jLsprqkeCMxdKWwY3Pv1lFcNmBvYe8A6k8qZc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788479808; c=relaxed/simple; bh=qUMYPh26RKG9DQ2MBUKAQjPzJozSmmkHPHb4Hjhc300=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TvthiqHQ6GbAZs81CEcprUb11aRSg8U7mOkAjU2T+GmNDALcHw62IBRS+2KnmcrVh8WHqWv8xd1YvVnoSPPirMGslcyd2lLvRJwmAd7NxjNsOIHCVygy3N68EtAwZP8DX5dHijHJWSe9iCUqCxxzAyscwi6NJPZ39tu96XbXpKA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=P/aujQWo; 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="P/aujQWo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 563DF1F00A3D; Thu, 3 Sep 2026 23:56:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788479801; bh=5xVzrZhZ+GoCWL6wOe9SgjftQb0pre8eyokaaoRKE+4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=P/aujQWo65yxO+vBufh0/pHn+IO8W8cKfjLZv2mj+6IF1LZs6bF/CcD4Ys4bxXSic MzMZUPx8Ua1H0soJEvvI1CHyeZUQM4RMoGaKSOHhr+E37+YhSeqq41Jh3bR3l8GIO0 SYHSQszWFAnuAL8FfPvzllFKi5ugXfkMOvD6+6cEewFs0G2Zuzz8rMmZ6I3EqXtvk8 in+sm91zxxEHOs8CZvtknm7RS+qCAUNRYxCJpvHeKhKFhxb+L8O1mAnhkM58LF2jYh VQS4obEMTli1hS/UcKnm1RsckmGhRRrTLtZmWP79Ewa2xGlZKRDcZ922fqQ8yRkY7J n5JbYZElpaLRg== From: Sasha Levin To: stable@vger.kernel.org Cc: Dev Jain , David Hildenbrand , Muchun Song , 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 2/2] mm/rmap: use huge_ptep_get() in try_to_unmap_one() Date: Thu, 3 Sep 2026 19:56:31 -0400 Message-ID: <20260903235631.1810157-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260903235631.1810157-1-sashal@kernel.org> References: <2026090344-unusual-yippee-a1d0@gregkh> <20260903235631.1810157-1-sashal@kernel.org> 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 f5407e9b697c940e78b27ff63c6e14d8d171adc3 ] Patch series "Fix incorrect access of hugetlb pte entries", v3. There are various places which use ptep_get() to get the pte entry corresponding to a hugetlb folio. Some arches (like s390) have special handling to compute the pteval, so they provide huge_ptep_get(). Use this helper consistently. Additionally, some code paths may provide huge_ptep_get with an unaligned address. This is a problem on arm64 (I checked other arches and it looks fine for them), which is fixed in patch 1. The fix is made to be backport-friendly: the cleaner fix would be to perhaps pass the hstate to huge_ptep_get() - that is wider churn and we can do that later. This patch (of 5): try_to_unmap_one() handles hugetlb folios when memory failure needs to replace a poisoned hugetlb mapping with a hwpoison entry. In that case page_vma_mapped_walk() returns the pte pointer to the hugetlb folio in pvmw.pte, but the code reads it 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. Just use huge_ptep_get() for dereferencing a huge pte pointer. Link: https://lore.kernel.org/20260703114202.365553-1-dev.jain@arm.com Link: https://lore.kernel.org/20260703114202.365553-3-dev.jain@arm.com Fixes: c7ab0d2fdc84 ("mm: convert try_to_unmap_one() to use page_vma_mapped_walk()") Signed-off-by: Dev Jain Reported-by: David Hildenbrand Reviewed-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 --- include/linux/hugetlb.h | 2 ++ mm/rmap.c | 16 ++++++++++------ 2 files changed, 12 insertions(+), 6 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index a3f6cdf8a2b6d..d09604498fa4d 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -1277,6 +1277,8 @@ static inline void hugetlb_count_sub(long l, struct mm_struct *mm) { } +pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, pte_t *ptep); + static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) { diff --git a/mm/rmap.c b/mm/rmap.c index 6053eb822a264..4348b35db465a 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1983,14 +1983,19 @@ static bool try_to_unmap_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. + */ const softleaf_t entry = softleaf_from_pte(pteval); pfn = softleaf_to_pfn(entry); @@ -1998,7 +2003,6 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, } subpage = folio_page(folio, pfn - folio_pfn(folio)); - address = pvmw.address; anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(subpage); -- 2.53.0