From nobody Sat Apr 11 02:17:51 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 93CE2C25B08 for ; Wed, 17 Aug 2022 06:21:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238932AbiHQGVq (ORCPT ); Wed, 17 Aug 2022 02:21:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48238 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238924AbiHQGVj (ORCPT ); Wed, 17 Aug 2022 02:21:39 -0400 Received: from out30-131.freemail.mail.aliyun.com (out30-131.freemail.mail.aliyun.com [115.124.30.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76F206FA31 for ; Tue, 16 Aug 2022 23:21:25 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R151e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045170;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0VMUBGX4_1660717281; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VMUBGX4_1660717281) by smtp.aliyun-inc.com; Wed, 17 Aug 2022 14:21:22 +0800 From: Baolin Wang To: sj@kernel.org, akpm@linux-foundation.org Cc: baolin.wang@linux.alibaba.com, damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm/damon: Validate if the pmd entry is present before accessing Date: Wed, 17 Aug 2022 14:21:12 +0800 Message-Id: <2838b6737bc259cf575ff11fd1c4b7fdb340fa73.1660717122.git.baolin.wang@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" The pmd_huge() is used to validate if the pmd entry is mapped by a huge page, also including the case of non-present (migration or hwpoisoned) pmd entry on arm64 or x86 architectures. Thus we should validate if it is present before making the pmd entry old or getting young state, otherwise we can not get the correct corresponding page. Signed-off-by: Baolin Wang Reviewed-by: SeongJae Park --- mm/damon/vaddr.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c index 3c7b9d6..1d16c6c 100644 --- a/mm/damon/vaddr.c +++ b/mm/damon/vaddr.c @@ -304,6 +304,11 @@ static int damon_mkold_pmd_entry(pmd_t *pmd, unsigned = long addr, =20 if (pmd_huge(*pmd)) { ptl =3D pmd_lock(walk->mm, pmd); + if (!pmd_present(*pmd)) { + spin_unlock(ptl); + return 0; + } + if (pmd_huge(*pmd)) { damon_pmdp_mkold(pmd, walk->mm, addr); spin_unlock(ptl); @@ -431,6 +436,11 @@ static int damon_young_pmd_entry(pmd_t *pmd, unsigned = long addr, #ifdef CONFIG_TRANSPARENT_HUGEPAGE if (pmd_huge(*pmd)) { ptl =3D pmd_lock(walk->mm, pmd); + if (!pmd_present(*pmd)) { + spin_unlock(ptl); + return 0; + } + if (!pmd_huge(*pmd)) { spin_unlock(ptl); goto regular_page; --=20 1.8.3.1