From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 12EA4C43458 for ; Fri, 3 Jul 2026 11:42:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=yg0lz8Jg9E5VcjlhmOCHXO4YaykLXADpl2rfVwfd4X0=; b=Uh5HT+padLZfm8wbFUg9Fe+Hx2 MqJwEhNpzsQn3oHkK4v8aV21XENBKjBYsqGeoJBWXLkbhDW+OXU7NI4zXrWu9BEPs3zMynNXIAFpy P10ZW4TdpLahEgpFtbTQEB7hzOH/t5rmgLIkaAz86S0KdsKJAMCy5SWCDelipoGOBM/BZhVEQAxCV gGngY0CEIPm89izmpq0e+r3WWW8ofXSGt4EXrhJfF63XwrLK0ylv6Bh9ShK/lnF8GZs2I6BivXGaN DQKTbQrahK+3Mq0XhCiy62V0gRR32JRE+mYnQA4WK/xJw5+YKi0EmezeJZJOJdJJE95D53cvvFKX4 t/TZ7DQQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wfcID-00000006pXw-3Q19; Fri, 03 Jul 2026 11:42:49 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wfcIA-00000006pVs-1Ntc for linux-arm-kernel@lists.infradead.org; Fri, 03 Jul 2026 11:42:48 +0000 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 61F7D3587; Fri, 3 Jul 2026 04:42:40 -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 85C5A3F673; Fri, 3 Jul 2026 04:42:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1783078964; bh=BRu+bhG7aKPiwT5vuH3zvlt7PlvdsDOhL/vNEPHmmuE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bZE5qae5+56oO0S3uNA4ZnaxllNJL7xt1NU0E09fQ779TxsZvP3TNcLz3cnjE+9yK aPal0ieAg0R7/f/NZT22vH0T1f8E7ieCwBTMhNTpGz/7JKySJSfrYj3blLLbOsbd5J JP0rBHMBYdhLeAFN9ToEtIptslmqlwFr3u/d4WVI= 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, apopple@nvidia.com, rcampbell@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, ak@linux.intel.com, nao.horiguchi@gmail.com, mel@csn.ul.ie, j-nomura@ce.jp.nec.com, pfalcato@suse.de, tglx@kernel.org, dave.hansen@intel.com, jpoimboe@kernel.org, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, stable@vger.kernel.org Subject: [PATCH v3 2/6] mm/rmap: use huge_ptep_get() in try_to_unmap_one() Date: Fri, 3 Jul 2026 11:41:55 +0000 Message-ID: <20260703114202.365553-3-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260703114202.365553-1-dev.jain@arm.com> References: <20260703114202.365553-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260703_044246_447336_F0286208 X-CRM114-Status: GOOD ( 12.21 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 Reported-by: David Hildenbrand Signed-off-by: Dev Jain --- 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 2abaf99321e90..6996d02acf171 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -1261,6 +1261,8 @@ 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 1c77d5dc06e9f..03737daa348c0 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2095,14 +2095,19 @@ 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); @@ -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