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 0E1F43ED3CF for ; Fri, 4 Sep 2026 15:17:15 +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=1788535038; cv=none; b=EGbMpjP0ZIVjpGo/A2ELutobTSuYnn8kX5dchZhqeEG3RcPTAvLziTejvwDbMqozu/xQ7tUQsFIZV6uRa6/pz2Mcvcs3P6kOzx9EYjPcfpJNmTxVsh96PDfmAKw3eGWEV0+smXn3yGLoH5Wj3KdDETdakg56fOPCtw5sDgwZ0YI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788535038; c=relaxed/simple; bh=xIDFQFQPESkS2JSUJnNkUfUYa1G4N4vLG1j8c2qfsLA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lfknChrqkJLDQSeMa11mYAby+zxRDLzAmBDmW70s46/94kKnUxkWwr/cBmURdXx6SWpVzxKlpYtkw7/tJ7D57LO9FqwFL1LT1UBETwEBsjVxUzRaFhhB28nXi4KOUEUNardCjd0N9bre3F49GqXWM83+9uNUhq8w+yWb+Ip9aMo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LAdyj18R; 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="LAdyj18R" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5613B1F00A3D; Fri, 4 Sep 2026 15:17:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788535035; bh=PTn/svM33MY8VWq1h3gKGOEuJl+5I3d0voc1gqBMWmo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LAdyj18R/oaJ8PstjyJRtZTH3QzxfAe7wLkmruADywq1SkrPD6IstFqt4aGHxoilw Kws+9fH0nwSQ+JxPDg3dQrBcxCCip0vQxqHdBtN7w/qoBrEbCLX+PiMq+TCSeEcmAe MhMzC3K4meaEXP41sygrKeBJjFpWB13odhaX+jAlEWTwtWE7P56grldXOUUUBshNdb 9yj7bfCpUGxsNiTYABM0sd3PY7i52BQU1inPxpXqXVuBudIsUWRWMq3HwOtVULxlq9 zEJNFTjLHVd2tFWfDNPylcqJPuEfvKpx09oxa4JotPuwdLFk5DmtFmkrQ/2qAEirpu KnMD4iuLqp0cw== 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 5.15.y] mm/rmap: use huge_ptep_get() in try_to_unmap_one() Date: Fri, 4 Sep 2026 11:17:10 -0400 Message-ID: <20260904151710.890678-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090347-esquire-pox-67eb@gregkh> References: <2026090347-esquire-pox-67eb@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 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 [ adapted folio and modern PTE accessors to page-based logic and the older huge_ptep_get() signature ] Signed-off-by: Sasha Levin --- include/linux/hugetlb.h | 2 ++ mm/rmap.c | 8 ++++++-- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 254fcd6f9604f..64a2c9e84bc12 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -1078,6 +1078,8 @@ static inline void hugetlb_count_sub(long l, struct mm_struct *mm) { } +pte_t huge_ptep_get(pte_t *ptep); + static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte, unsigned long sz) { diff --git a/mm/rmap.c b/mm/rmap.c index c103e01d22327..202c13b8aa3e5 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1465,8 +1465,12 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, /* Unexpected PMD-mapped THP? */ VM_BUG_ON_PAGE(!pvmw.pte, page); - subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte); address = pvmw.address; + if (PageHuge(page)) + pteval = huge_ptep_get(pvmw.pte); + else + pteval = *pvmw.pte; + subpage = page - page_to_pfn(page) + pte_pfn(pteval); if (PageHuge(page) && !PageAnon(page)) { struct mmu_gather tlb; @@ -1503,7 +1507,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, } /* Nuke the page table entry. */ - flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); + flush_cache_page(vma, address, pte_pfn(pteval)); if (should_defer_flush(mm, flags)) { /* * We clear the PTE but do not flush so potentially -- 2.53.0