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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E482C7EE29 for ; Fri, 2 Jun 2023 18:39:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237006AbjFBSjQ (ORCPT ); Fri, 2 Jun 2023 14:39:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47626 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235751AbjFBSjO (ORCPT ); Fri, 2 Jun 2023 14:39:14 -0400 Received: from NAM11-DM6-obe.outbound.protection.outlook.com (mail-dm6nam11on2067.outbound.protection.outlook.com [40.107.223.67]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE544197; Fri, 2 Jun 2023 11:39:12 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=SaB+C8UG5E931Evt4NClc8qctY5GzK6PddFs4gwQO4RjpKWzXw4dkN65VIoPoNkp6eJgxalKFRndavyJlKakl4GPnky98btdEpfV6sd+KqXXNWz9VFQWpELN6S73z2aWVrO3W9CROdkQMvpOSiDBwzA+MiaMOja84X5bw+XW0/0pCxxlKTxcGv9jfL04ZzsDnSnkLUb2G01I/HvW5xdzikYf92k7cYuSZhqu7J0X5HxgqNNIvFEvGQgFI4YcolH/7p/GXPID8D7qlTI7RJhxpluF4r5i4V0hYYPs2be7as2rFFD+gZpq/jZy5Ymf5lU/TVyzb1mWSKw6v8c7f8lLQQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=ZsqlgU9U3Arr1OKeQhUZoeQlAfNl/gvZumbSJ6rjad4=; b=WqZ6ifVtlvWePeCeUj+3uhfgdJsk0N/c8LcSSrCZZlzcagEeKea16GkFFq7vTMZgwhtsvvBJPSH9Ww0dt4mTSAlo0/93TIYvxCGdQH0cmOX9NCLUQk6rcQqS7ePGahKMj1xWJsvl2X+jnfRo4/O7gMTw9MuqjxLYz1TuURkVF1was4ZrsMYzDAzMLY9SwsuyQ+AvKE3ij5CHQudBCcp9e6c2N58BrEF+1x8w6uAdetoP4jzCoo74a0uWJUL+kzQo9chUKtkO5DUFtMtuBsSllA4MaXmEjTZBmsW5Td0qFqgPsQua13WXslk8dIU8DAtE17M+eQrcScLAkWcIfuuwaw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 216.228.117.160) smtp.rcpttodomain=redhat.com smtp.mailfrom=nvidia.com; dmarc=pass (p=reject sp=reject pct=100) action=none header.from=nvidia.com; dkim=none (message not signed); arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=Nvidia.com; s=selector2; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=ZsqlgU9U3Arr1OKeQhUZoeQlAfNl/gvZumbSJ6rjad4=; b=AhGWn8qMYPuYHy8uu5M8FWoBPLYsE1pFbWevPNaSk2eknR+FnvjFJlwJBy6Yi+jgB6BBJH16OoJcsYjozRRQpmgJY+jwr3XVNCvIKWlas+wpnf5FfakYA8gUWFspncFEauMps0hR76amWv6ta62tvAmPETu8PRt+SsX5z6qjwGLoz14AKo4ByDDhtQzTAH8f4P5m/aXgMGhefP1l0i/fQ/Ie33jfMOgCKtWR+G814BeicDCAn37jdS8TF04LtbFa+4ao3fKAH2DWcxphWL2ZNraLF3O8IqYi86BIaZ7bOirCkmWRM9sIRnG26KAVSt1sfVyHZlxAtjRARP+KG0vcGw== Received: from BN9PR03CA0288.namprd03.prod.outlook.com (2603:10b6:408:f5::23) by PH0PR12MB7472.namprd12.prod.outlook.com (2603:10b6:510:1e9::9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6455.24; Fri, 2 Jun 2023 18:39:08 +0000 Received: from BL02EPF000145BB.namprd05.prod.outlook.com (2603:10b6:408:f5:cafe::fa) by BN9PR03CA0288.outlook.office365.com (2603:10b6:408:f5::23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6455.24 via Frontend Transport; Fri, 2 Jun 2023 18:39:08 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 216.228.117.160) smtp.mailfrom=nvidia.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=nvidia.com; Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates 216.228.117.160 as permitted sender) receiver=protection.outlook.com; client-ip=216.228.117.160; helo=mail.nvidia.com; pr=C Received: from mail.nvidia.com (216.228.117.160) by BL02EPF000145BB.mail.protection.outlook.com (10.167.241.211) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6477.13 via Frontend Transport; Fri, 2 Jun 2023 18:39:08 +0000 Received: from rnnvmail201.nvidia.com (10.129.68.8) by mail.nvidia.com (10.129.200.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.5; Fri, 2 Jun 2023 11:38:54 -0700 Received: from [10.110.48.28] (10.126.231.35) by rnnvmail201.nvidia.com (10.129.68.8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.37; Fri, 2 Jun 2023 11:38:53 -0700 Message-ID: Date: Fri, 2 Jun 2023 11:38:53 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.2 Subject: Re: [PATCH 02/12] selftests/mm: fix unused variable warning in hugetlb-madvise.c Content-Language: en-US To: David Hildenbrand , Andrew Morton CC: Peter Xu , Shuah Khan , "Nathan Chancellor" , , , LKML References: <20230602013358.900637-1-jhubbard@nvidia.com> <20230602013358.900637-3-jhubbard@nvidia.com> From: John Hubbard In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.126.231.35] X-ClientProxiedBy: rnnvmail203.nvidia.com (10.129.68.9) To rnnvmail201.nvidia.com (10.129.68.8) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL02EPF000145BB:EE_|PH0PR12MB7472:EE_ X-MS-Office365-Filtering-Correlation-Id: 22feb0c9-115d-4051-83b0-08db6398a68c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.117.160;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge1.nvidia.com;CAT:NONE;SFS:(13230028)(4636009)(136003)(376002)(346002)(396003)(39860400002)(451199021)(46966006)(40470700004)(36840700001)(40460700003)(186003)(53546011)(26005)(16526019)(316002)(36860700001)(47076005)(426003)(2616005)(41300700001)(83380400001)(336012)(5660300002)(8936002)(2906002)(8676002)(478600001)(70586007)(70206006)(16576012)(110136005)(54906003)(86362001)(40480700001)(36756003)(31696002)(4326008)(356005)(82740400003)(7636003)(82310400005)(31686004)(43740500002);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Jun 2023 18:39:08.1275 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 22feb0c9-115d-4051-83b0-08db6398a68c X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BL02EPF000145BB.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR12MB7472 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/2/23 03:01, David Hildenbrand wrote: > On 02.06.23 03:33, John Hubbard wrote: >> The dummy variable is required in order to make this work, so declare it >> as volatile in order to avoid the clang compiler warning. >> >> Signed-off-by: John Hubbard >> --- >>   tools/testing/selftests/mm/hugetlb-madvise.c | 2 +- >>   1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/tools/testing/selftests/mm/hugetlb-madvise.c b/tools/testing/selftests/mm/hugetlb-madvise.c >> index 28426e30d9bc..3296ccaf7525 100644 >> --- a/tools/testing/selftests/mm/hugetlb-madvise.c >> +++ b/tools/testing/selftests/mm/hugetlb-madvise.c >> @@ -65,7 +65,7 @@ void write_fault_pages(void *addr, unsigned long nr_pages) >>   void read_fault_pages(void *addr, unsigned long nr_pages) >>   { >> -    unsigned long dummy = 0; >> +    volatile unsigned long dummy = 0; >>       unsigned long i; >>       for (i = 0; i < nr_pages; i++) > > The compiler can still decide to optimize it all out, because it's not a global variable. > > > Placing a > > asm volatile("" : "+r" (dummy)); > > after the write tells the compiler that the value will be read and cannot be optimized out (we use that trick in the cow selftest and I've been using it in QEMU for the same purpose as well). > Done. I will send a v2 with this, thanks! thanks, -- John Hubbard NVIDIA