From nobody Sat Apr 11 21:02:08 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2C5CC00140 for ; Fri, 5 Aug 2022 16:00:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240931AbiHEQAO (ORCPT ); Fri, 5 Aug 2022 12:00:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39274 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238497AbiHEQAM (ORCPT ); Fri, 5 Aug 2022 12:00:12 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 4CD421C2 for ; Fri, 5 Aug 2022 09:00:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1659715208; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=I84jJZh3uMy8OjbvjnM/V7a2QEPXmVsEuIStQ5Ektjw=; b=U9oBtOfDFZDcPLfhFSPmRWkrEyYBV2GzyjYfhVDwpWqvv51vNnEaSiWhQ0QK2wN1uHL24D xKFo89MxBfCecU6uU4EHbgeh2VjRwpT0VJ4yXiV2+R9e5TppW1+nFh88Wxofnl8TlGHXzN XhZGVT1CofBFxMWOTdSp0DdhfcixHw4= Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-592-evv8nOt-PEKAmk78xPeHlA-1; Fri, 05 Aug 2022 12:00:07 -0400 X-MC-Unique: evv8nOt-PEKAmk78xPeHlA-1 Received: by mail-qt1-f198.google.com with SMTP id a6-20020ac86106000000b0033f73d965acso2185921qtm.7 for ; Fri, 05 Aug 2022 09:00:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc; bh=I84jJZh3uMy8OjbvjnM/V7a2QEPXmVsEuIStQ5Ektjw=; b=A+I2P72mxfVL0tR6b/rp7FJptV/QAeZl6dCSQQAN8km4uykUGE2X4FoCGaoEs2tB5k 8F/MflOPU2o9RrQbnC6hLPcmEFy1eehHNa0xWJtPo4PFGLRTS3Rc5XE634vY7ouFkv61 8QOLOgavEAEySaiAk31YwTG/x4qJWAIaNc04Oj+oQtFsP2LvQMSBlUBAUlE9YzNG+nlm 1t851ZV2M0TMJbYuuwuA2HLOqGowOy6AOIMl3Bv7e3z7k2N2hbuS1NgLmtHXstJRUQQY eOYCvcnsHYXmxO2YYuSJZpTwPVUbNXvErPtOcAtt+gWWaVuuZpVsoTIu+BvknxFcK909 fSLA== X-Gm-Message-State: ACgBeo0Dy3O3YHyXJU+5FSg40VLwDp8hnIWpnIHRl5GD0DclAVMr8Jgo yUIJN8ibRmLLkVeo0u6OqsU1u/C8lANoA8yrPxJndTbevqBygcsCZMU5WjLcBuBhscEbuXaxO5J B6bVFkM9YzycewQ59nPZekhkzPg1+YC4r6CXse53qkENNsHOgcJzYuK+hXfzt3zXhjHIyQzCsMg == X-Received: by 2002:a05:622a:4c7:b0:31f:dd6:93ca with SMTP id q7-20020a05622a04c700b0031f0dd693camr6296157qtx.526.1659715206447; Fri, 05 Aug 2022 09:00:06 -0700 (PDT) X-Google-Smtp-Source: AA6agR6PHOhKBqkOUNsdNVGM60zSMR0a7lfTCil/iE/ktiqNKF6nIKAk9dOBI8Mxu+yZTUrPUrRYRw== X-Received: by 2002:a05:622a:4c7:b0:31f:dd6:93ca with SMTP id q7-20020a05622a04c700b0031f0dd693camr6296114qtx.526.1659715206125; Fri, 05 Aug 2022 09:00:06 -0700 (PDT) Received: from localhost.localdomain (bras-base-aurron9127w-grc-35-70-27-3-10.dsl.bell.ca. [70.27.3.10]) by smtp.gmail.com with ESMTPSA id r19-20020ac84253000000b0033b9c5c27dfsm2743047qtm.16.2022.08.05.09.00.04 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 05 Aug 2022 09:00:05 -0700 (PDT) From: Peter Xu To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Yang Shi , David Hildenbrand , peterx@redhat.com, Nadav Amit , Andrew Morton , Konstantin Khlebnikov , Huang Ying , Vlastimil Babka Subject: [PATCH v2] mm/smaps: Don't access young/dirty bit if pte unpresent Date: Fri, 5 Aug 2022 12:00:03 -0400 Message-Id: <20220805160003.58929-1-peterx@redhat.com> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" These bits should only be valid when the ptes are present. Introducing two booleans for it and set it to false when !pte_present() for both pte and pmd accountings. The bug is found during code reading and no real world issue reported, but logically such an error can cause incorrect readings for either smaps or smaps_rollup output on quite a few fields. For example, it could cause over-estimate on values like Shared_Dirty, Private_Dirty, Referenced. Or it could also cause under-estimate on values like LazyFree, Shared_Clean, Private_Clean. Cc: Konstantin Khlebnikov Cc: Huang Ying Fixes: b1d4d9e0cbd0 ("proc/smaps: carefully handle migration entries") Fixes: c94b6923fa0a ("/proc/PID/smaps: Add PMD migration entry parsing") Reviewed-by: Vlastimil Babka Reviewed-by: David Hildenbrand Reviewed-by: Yang Shi Signed-off-by: Peter Xu Reviewed-by: "Huang, Ying" --- fs/proc/task_mmu.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 9913f3be9fd2..d56c65f98d00 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -527,10 +527,12 @@ static void smaps_pte_entry(pte_t *pte, unsigned long= addr, struct vm_area_struct *vma =3D walk->vma; bool locked =3D !!(vma->vm_flags & VM_LOCKED); struct page *page =3D NULL; - bool migration =3D false; + bool migration =3D false, young =3D false, dirty =3D false; =20 if (pte_present(*pte)) { page =3D vm_normal_page(vma, addr, *pte); + young =3D pte_young(*pte); + dirty =3D pte_dirty(*pte); } else if (is_swap_pte(*pte)) { swp_entry_t swpent =3D pte_to_swp_entry(*pte); =20 @@ -560,8 +562,7 @@ static void smaps_pte_entry(pte_t *pte, unsigned long a= ddr, if (!page) return; =20 - smaps_account(mss, page, false, pte_young(*pte), pte_dirty(*pte), - locked, migration); + smaps_account(mss, page, false, young, dirty, locked, migration); } =20 #ifdef CONFIG_TRANSPARENT_HUGEPAGE @@ -572,11 +573,13 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long= addr, struct vm_area_struct *vma =3D walk->vma; bool locked =3D !!(vma->vm_flags & VM_LOCKED); struct page *page =3D NULL; - bool migration =3D false; + bool migration =3D false, young =3D false, dirty =3D false; =20 if (pmd_present(*pmd)) { /* FOLL_DUMP will return -EFAULT on huge zero page */ page =3D follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP); + young =3D pmd_young(*pmd); + dirty =3D pmd_dirty(*pmd); } else if (unlikely(thp_migration_supported() && is_swap_pmd(*pmd))) { swp_entry_t entry =3D pmd_to_swp_entry(*pmd); =20 @@ -596,8 +599,7 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long a= ddr, else mss->file_thp +=3D HPAGE_PMD_SIZE; =20 - smaps_account(mss, page, true, pmd_young(*pmd), pmd_dirty(*pmd), - locked, migration); + smaps_account(mss, page, true, young, dirty, locked, migration); } #else static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr, --=20 2.32.0