From nobody Mon Feb 9 12:08:57 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 13802EB64DD for ; Tue, 11 Jul 2023 05:50:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230379AbjGKFu3 (ORCPT ); Tue, 11 Jul 2023 01:50:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34846 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230015AbjGKFuI (ORCPT ); Tue, 11 Jul 2023 01:50:08 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3FF441BC for ; Mon, 10 Jul 2023 22:50:07 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4R0VHv0DmQztR5C; Tue, 11 Jul 2023 13:47:07 +0800 (CST) Received: from huawei.com (10.174.151.185) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Tue, 11 Jul 2023 13:50:04 +0800 From: Miaohe Lin To: , CC: , , Subject: [PATCH v2 8/8] mm: memory-failure: fix race window when trying to get hugetlb folio Date: Tue, 11 Jul 2023 13:50:16 +0800 Message-ID: <20230711055016.2286677-9-linmiaohe@huawei.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20230711055016.2286677-1-linmiaohe@huawei.com> References: <20230711055016.2286677-1-linmiaohe@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.174.151.185] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" page_folio() is fetched before calling get_hwpoison_hugetlb_folio() without hugetlb_lock being held. So hugetlb page could be demoted before get_hwpoison_hugetlb_folio() holding hugetlb_lock but after page_folio() is fetched. So get_hwpoison_hugetlb_folio() will hold unexpected extra refcnt of hugetlb folio while leaving demoted page un-refcnted. Fixes: 25182f05ffed ("mm,hwpoison: fix race with hugetlb page allocation") Signed-off-by: Miaohe Lin Acked-by: Naoya Horiguchi --- mm/memory-failure.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index af34fd4669d3..9ab97016877e 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1383,8 +1383,15 @@ static int __get_hwpoison_page(struct page *page, un= signed long flags) bool hugetlb =3D false; =20 ret =3D get_hwpoison_hugetlb_folio(folio, &hugetlb, false); - if (hugetlb) - return ret; + if (hugetlb) { + /* Make sure hugetlb demotion did not happen from under us. */ + if (folio =3D=3D page_folio(page)) + return ret; + if (ret > 0) { + folio_put(folio); + folio =3D page_folio(page); + } + } =20 /* * This check prevents from calling folio_try_get() for any @@ -1473,8 +1480,13 @@ static int __get_unpoison_page(struct page *page) bool hugetlb =3D false; =20 ret =3D get_hwpoison_hugetlb_folio(folio, &hugetlb, true); - if (hugetlb) - return ret; + if (hugetlb) { + /* Make sure hugetlb demotion did not happen from under us. */ + if (folio =3D=3D page_folio(page)) + return ret; + if (ret > 0) + folio_put(folio); + } =20 /* * PageHWPoisonTakenOff pages are not only marked as PG_hwpoison, --=20 2.33.0