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b=fD8KNrroF2uUGCBP2oPRa/XA29qNWeWrTNGlBKSfw+vXjriVn4ZqsT7eqwI/0doOIMSrPRP17dyoWjTf5ktpzqr0FUnNjK+tfsL0lnXGEFYHQciutBCEavd8ErrW1GDxU39WvsU6Ctzo8lWtVBjDvmEk8RxNk23SbXLILmoDxe1SoE1p4t5Yzss/G692f3Wl9WhpfTriqtU/LhitPtctprfXAid8fyVfAV573584MoRjl8Sy4yRjrwZx2Y4CriREbsp3M1hXHyQiX58Sh56OhUzvmj+unFvxX95Im3nhFtytXsFgRW7V84f80QKThxM8hh+rtom8wmgLEvRRFGPHXg== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nvidia.com; Received: from DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) by SN7PR12MB7300.namprd12.prod.outlook.com (2603:10b6:806:298::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8922.39; Fri, 18 Jul 2025 15:11:26 +0000 Received: from DS7PR12MB9473.namprd12.prod.outlook.com ([fe80::5189:ecec:d84a:133a]) by DS7PR12MB9473.namprd12.prod.outlook.com ([fe80::5189:ecec:d84a:133a%6]) with mapi id 15.20.8922.037; Fri, 18 Jul 2025 15:11:26 +0000 From: Zi Yan To: wang lian Cc: akpm@linux-foundation.org, broonie@kernel.org, david@redhat.com, lorenzo.stoakes@oracle.com, sj@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, brauner@kernel.org, gkwang@linx-info.com, jannh@google.com, Liam.Howlett@oracle.com, ludovico.zy.wu@gmail.com, p1ucky0923@gmail.com, richard.weiyang@gmail.com, ryncsn@gmail.com, shuah@kernel.org, vbabka@suse.cz, zijing.zhang@proton.me Subject: Re: [PATCH 1/2] selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));" Date: Fri, 18 Jul 2025 11:11:23 -0400 X-Mailer: MailMate (2.0r6272) Message-ID: <2173758C-0BFE-4AFE-BF46-A32F69F1CBCA@nvidia.com> In-Reply-To: <20250717131857.59909-2-lianux.mm@gmail.com> References: <20250717131857.59909-1-lianux.mm@gmail.com> <20250717131857.59909-2-lianux.mm@gmail.com> Content-Type: text/plain Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: BL1PR13CA0389.namprd13.prod.outlook.com (2603:10b6:208:2c0::34) To DS7PR12MB9473.namprd12.prod.outlook.com (2603:10b6:8:252::5) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS7PR12MB9473:EE_|SN7PR12MB7300:EE_ X-MS-Office365-Filtering-Correlation-Id: 54c8e85b-2bcf-4c84-ba16-08ddc60d5db1 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|1800799024|366016|7053199007; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?il6jDr67iIPaQNQeOvpABOpxx/RrBLaTRcfDCloUKIGtjcKCT271agdcuk8m?= =?us-ascii?Q?x4ULWfp/EJ4uAyrgssXE/pL2Tsoxgjh/XNuw1PM2WMZoomi/S5UgL9gFlW4o?= =?us-ascii?Q?aUm70nqglfdxOlYNdH76c3V0ySh++GYfUWzE7FtumjrSVMlgZ7txkpCDYuBJ?= =?us-ascii?Q?ByrhTsmsuctB6GHrL6bfhF+wYvzLWpaCC/xkstj1fh39pwtjrPIVnE486EFe?= =?us-ascii?Q?3n/x8O0oFSFHOVin375Ct2gN4egzAkGcCcIdJvZWEMtq+ANpvkGhYizmYF1k?= =?us-ascii?Q?Ph97NyT/WhyEO8jMyZ/uGRGfxnVHiTfaWbX431C0WnC4UbYGvt7B/NicGEcK?= =?us-ascii?Q?AaCZQNiOxNxCMGR0qKX4TADfvwFV43eh8Vtw48YCCklN7qcTXsmJqZA9ByYl?= =?us-ascii?Q?eIBcD6NC3RlKNjKZLaBAYmdgiyMoqYYZrI6Lv6N2s4kw2xXM5GVZ8iva/FGv?= =?us-ascii?Q?iU1PGhKdlAH2QOASxaXp/vUPw5hGSOX+zHanu75ht4AC6k7iFFntSZcWUUIe?= =?us-ascii?Q?T0NYo/RAMJmCsSmnkfQPZK5pgtbt772K89aRGAh+cHuOlkt00oBOTeOcH/w0?= =?us-ascii?Q?7vE0iSMc770x1umsh9mn8TOZOfiZGzUtqYqMaLTz5Y6Zb2S3ixy+RTRdMEBu?= =?us-ascii?Q?+FFoIONsM7bwPt6/7ZX1ATtHPxKcf78XGKUkzRscj6XVW8x07NTnxdzq8GeM?= =?us-ascii?Q?R7+MvwgtFuX53kIfx5lM/O4RkRA/4iWR/JyxpIevGuHabQ77ajO75I0CxtaD?= =?us-ascii?Q?5XlLPcgCeIkMk1f4SG6O/e0edwJmbusJKVRYcoLDs3WxC3LO1CbgstslUwuI?= =?us-ascii?Q?XkgA9ORlR755JWRNwmhsdQBFVrM0RJ41Hram7k2b59KlhxM4deP9VFBrZMoD?= =?us-ascii?Q?pKPDYH4J43biF1vGEL6aKOx8iqk97mqQOFvY/e06boN1ZHhPYY8GWYbaE2AG?= =?us-ascii?Q?b/9Fv+ucJ/OGfG3PlmaXHq/j7zCS/xUVVVfxY+ewAuy1qb1iTGX/SINzKiTg?= =?us-ascii?Q?aP0rHFJph4+oA4Lu8J0OqyoLseG78Sj/odf/fkyaYkRQPB6TklRg91tAreYj?= =?us-ascii?Q?fosBMynTB2bIiGwfldpZLtlUuIiqjnSKMjSm4lKw0ySrRJ0DyAWTNKlSOhk8?= =?us-ascii?Q?eUCbidNihqB5IGfhztgA1Z1gJKNiPNDx6FEphUxZOhBFStXG6u3sgb8KU4cR?= =?us-ascii?Q?na0YAHuUR16BDCM8KcFZ9HIBe8XCO2Ia8Rx9bTb8HoCOiZ6W4WepDsHTEJ0x?= =?us-ascii?Q?1VF0XRK3x0AZMYAqn8ZvAXP+uOheZaM2TwBs1sfWq628QXoERgSb6RHfRdvJ?= =?us-ascii?Q?CSMtmZg3twKtABSlt6ejXjG/kKHzi9rX6elq/Qw3j1ONATmqN58Cr8g0fM0S?= =?us-ascii?Q?S0UgJN1T/4kI2ftoQsSUegXkSMxb+kw6cVO0Ye6IRmLc+vxgH33/hHOCt6z3?= =?us-ascii?Q?6ph9rGjf6dJYKf7RuLB1NhD0uQRJb1ysAUPErN7ViiuIn+oTIxm4EiWQ4zA9?= =?us-ascii?Q?XxZBJ7XwL3Xg9sGtJHe4gCKyY22qjss7SZjAg7sZZViq5aPIVDHv0wGLaEVL?= =?us-ascii?Q?je8RXEG8npVjLRIdXeENoIfJv1c5fn47xEhunI5E?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 54c8e85b-2bcf-4c84-ba16-08ddc60d5db1 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Jul 2025 15:11:26.6938 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: AF8YuRCGYIvbtHSX6gASZ/I7xk1tiUwd4GTT8xKL/oPCQDYsLVdpSmBXoIbqRPmg X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN7PR12MB7300 On 17 Jul 2025, at 9:18, wang lian wrote: > Several mm selftests use the `asm volatile("" : "+r" (variable));` > construct to force a read of a variable, preventing the compiler from > optimizing away the memory access. This idiom is cryptic and duplicated= > across multiple test files. > > Following a suggestion from David[1], this patch refactors this > common pattern into a FORCE_READ() macro > > [1] https://lore.kernel.org/lkml/4a3e0759-caa1-4cfa-bc3f-402593f1eee3@r= edhat.com/ > > Signed-off-by: wang lian > Reviewed-by: Lorenzo Stoakes > --- > tools/testing/selftests/mm/cow.c | 30 +++++++++----------= > tools/testing/selftests/mm/guard-regions.c | 7 ----- > tools/testing/selftests/mm/hugetlb-madvise.c | 5 +--- > tools/testing/selftests/mm/migration.c | 13 ++++---- > tools/testing/selftests/mm/pagemap_ioctl.c | 4 +-- > .../selftests/mm/split_huge_page_test.c | 4 +-- > tools/testing/selftests/mm/vm_util.h | 7 +++++ > 7 files changed, 31 insertions(+), 39 deletions(-) Reviewed-by: Zi Yan Best Regards, Yan, Zi