From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9921D3AA500; Thu, 25 Jun 2026 11:30:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782387022; cv=none; b=AhYFyjWqDrzMGvdhSLloidcBguqC22MJlplreNIm0qIvFQUQ4cTf94syDYu/vp/fXE7aYDL42cAAloQQyGdqYXY2UC70CQwvaBI4SkIMg/InwDtTQhKrEsNH5oZQX1Q8gEDdAEmLlXd/LSbTdWlk//OzgzU5dDW8ISVGC+b101o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782387022; c=relaxed/simple; bh=QtQ8GPWloMli0RbtDXW5k6ZOS1ivmXc5LVDMq/8ZE0s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KLRivjock9ut6UN8XGeJOz/CEf4NMM1i3ZlLzUpfP5WL203zIHAKoCJ2rtWvJgwvVqDgwRxQJNIuWMo9shfWjREdndHCkX9T6EuKDHWHjanzHwyp+K42vxzfrFhJv1so5EA57ANQmc6ljXONriy1Uac4w3PWiMkK+bOy4WHUofY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=VaLjxRt3; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="VaLjxRt3" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5847D2C46; Thu, 25 Jun 2026 04:30:15 -0700 (PDT) Received: from cesw-amp-gbt-1s-m12830-01.blr.arm.com (cesw-amp-gbt-1s-m12830-01.blr.arm.com [10.164.195.31]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 065623F62B; Thu, 25 Jun 2026 04:30:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1782387019; bh=QtQ8GPWloMli0RbtDXW5k6ZOS1ivmXc5LVDMq/8ZE0s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VaLjxRt3/7/p0anZpXqR8+DAL6bdCNHL3CUiUSzwJtBPmWo0qYBn1WDY7pWuXqFjq monTMitTvtDfW8B6chmLjY8d3MAnHyUbwQQ7tVbf2qGbaIDhJWU8jioydOr+eHztTW X7Rif88PZSY7xHy3jhDuCDhfJBZtdzD21Ro+O/BM= From: Dev Jain To: muchun.song@linux.dev, osalvador@suse.de, akpm@linux-foundation.org, ljs@kernel.org, david@kernel.org, liam@infradead.org Cc: Dev Jain , riel@surriel.com, vbabka@kernel.org, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, kas@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcampbell@nvidia.com, apopple@nvidia.com, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, mel@csn.ul.ie, nao.horiguchi@gmail.com, ak@linux.intel.com, j-nomura@ce.jp.nec.com, pfalcato@suse.de, dave.hansen@intel.com, tglx@kernel.org, jpoimboe@kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, stable@vger.kernel.org Subject: [PATCH 1/5] mm/rmap: use huge_ptep_get() in try_to_unmap_one() Date: Thu, 25 Jun 2026 11:29:50 +0000 Message-ID: <20260625112955.3254283-2-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260625112955.3254283-1-dev.jain@arm.com> References: <20260625112955.3254283-1-dev.jain@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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. Fixes: c7ab0d2fdc84 ("mm: convert try_to_unmap_one() to use page_vma_mapped_walk()") Cc: stable@vger.kernel.org Signed-off-by: Dev Jain --- include/linux/hugetlb.h | 3 +++ mm/rmap.c | 16 ++++++++++------ 2 files changed, 13 insertions(+), 6 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 2abaf99321e90..fdb7bdf7645c5 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -1261,6 +1261,9 @@ 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 1c77d5dc06e9f..aa8a254efaecc 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2095,11 +2095,16 @@ 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 { + /* + * Handle PFN swap PTEs, such as device-exclusive ones, + * that actually map pages. + */ + pteval = ptep_get(pvmw.pte); + } if (likely(pte_present(pteval))) { pfn = pte_pfn(pteval); } else { @@ -2110,7 +2115,6 @@ 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); -- 2.43.0