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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Matthew Wilcox , Bas van Dijk , Eero Kelly , Andrew Battat , Adam Bratschi-Kaye , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v4] selftests/mm: add folio_split() and filemap_get_entry() race test Date: Fri, 20 Mar 2026 14:00:18 -0400 X-Mailer: MailMate (2.0r6290) Message-ID: In-Reply-To: <20260320142219.375118-1-ziy@nvidia.com> References: <20260320142219.375118-1-ziy@nvidia.com> Content-Type: text/plain Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: BY3PR03CA0019.namprd03.prod.outlook.com (2603:10b6:a03:39a::24) 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_|SA1PR12MB6993:EE_ X-MS-Office365-Filtering-Correlation-Id: a8d1ea41-d04e-45ae-4a0c-08de86aa91c3 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|7416014|366016|18002099003|22082099003|56012099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?g+SYg3RlzqxBo8XopCuPaaKdJYynv7WMZefa12qhHSkqd/eXOLgT4EUFTCm+?= =?us-ascii?Q?1ik51U7u2c5FITjQmPLg7WY/d9MK8jGOCTMX2aLe5HjajLTcAorQZNZdVf+p?= =?us-ascii?Q?pncbqVilcrkH9kDDVfwR1hJeqbdvWIrovQvhn6RQyZjuFfxLr/pHfiYtlawJ?= =?us-ascii?Q?jzpZEH88yDhqow3RRKjOo2XQK/fmMEoGgAFTSqH7Ye/Qd76ejW0bF5LwyWln?= =?us-ascii?Q?JIUxY+kXEp+38/oF2bx2VFDVjRvc7iT+edsMy5cGLnJSY0TmVHW1owcMdmDm?= =?us-ascii?Q?v1T/MIg96vPsp8amC+juFI1vuCJ4L4MwRSjZM+huqA8Ibjm6hBnKL7IcjSEB?= =?us-ascii?Q?SLVmF6Mfw1wLCX+qObpcUjOlm0LbmCCVwxqK3xO9W6o9QPRakSvuEOZzwW1L?= =?us-ascii?Q?VGLSZPc80fgOzp6QPmp3mMMHDALBAsvIbu9pG2O5QsoLvtjf15ouL65bSua2?= =?us-ascii?Q?uD2Eeu4zEMNH4Kl3b72Y6IfVoxcgc2xxwEq1pE2K+mIGtxbLZCKPI8I1s1sM?= =?us-ascii?Q?BepeiD/0izhMhx0JtHG6HNANqVQ2+mBNvRGapcMkAi0vnpMGZ7uEU/iPNf/J?= =?us-ascii?Q?pucv2Yh4zh7GBnFyYaQ8AgIdoNcKcY+tESSsSu8mJ+nnGDPYs2+jsS6haV9+?= =?us-ascii?Q?YXwiBeBHuRoDzpb1rsyLiD+TCzJd0n4gKg6iRJOnwzK2D4ycNjLNFSY9zYAz?= =?us-ascii?Q?IGJGEM96hRHAf9/g4sOz5u0LJoUOBsYIdi0bLK9pwP/MF3FyaoieqVno8S4j?= =?us-ascii?Q?RVIAjwwuiWYkqdp/6OEci+NMXMus4A4DHn9VjLlml5ZY4saM0wPpmtYRFORW?= =?us-ascii?Q?rxyfsHLI6TtaHu1Vrq36jHQcC3JODBFNSAF489N29TjAY7HhAivEghBihD5W?= =?us-ascii?Q?OsdJMBRGFyFLOVbnGOMfIFrkboO5fwJKDqxKIYaiwBbb44vuIUIeF3fcmvMa?= =?us-ascii?Q?Y1BunjmmpUviO8jpPuywv+WpMZ+3JsI8deUmfxSgLlWlUsQtYLpg0hTUAw59?= =?us-ascii?Q?3Gv3VU3wLPdVTUT9atgIHJlk/0Ckcvbm5FQLUs6gCvc3O/HzvGMzSVJXyptl?= =?us-ascii?Q?Pc9qwosSqC8nGn0A7qkxtFS7F3U8O1NXJFytsoY9t1842Au3VBg72ybQa6w6?= =?us-ascii?Q?m7EodooyIryQKag19EpVXoPDd3kr9jv/rBQS5kPYAe37NpDFwrIheAZBoD/L?= =?us-ascii?Q?WZKl3K+m8H9OKg8I7upQ3Sm3biCu7kZp3YscuOq17nN8QNXYU7tMbRQjwEQG?= =?us-ascii?Q?2YtN4mstRlrVat2nnlljKc8S/xdIaOT9M6Tb09uH3d2+epEHM7GkZPgnlc4I?= =?us-ascii?Q?jNatNDia2qlCtyudp/ZnDdVnUeE8qT8tNh1frKuy07rgTGftbo432kz+h/6L?= =?us-ascii?Q?cavbo4Zmx0TYGpr29Y820OZPMxp2ZjNbP7P8FMyLdSq2Z47VcKxquNLk34xe?= =?us-ascii?Q?jKiUgdO6pCzrpq6beQpSM7MeArtW7LvPUkay2Mn1PhyWtVvspQJglfTG8jZY?= =?us-ascii?Q?IOALXwZ5n/xx4tAjvxGhQNorbm4gsFe8Yv2d+PfzEkVsnJp1Ow/THLPqUOAi?= =?us-ascii?Q?/KuGvhLRGfJatFYK5mHDxYCZisYoPlatALV0vbOGlWHfQw3ozfPo81TT3ftO?= =?us-ascii?Q?YaFwbsSUyhcUVargcPilHYv/Mpy10KxdO5WkXe7/0QZAxhsZPpv3zY49GXMP?= =?us-ascii?Q?u/NDD5vUAhz+nGG7Z06XDYwKvX3GnmchCKenm+hzGNGAg9UMUeFNRhCNqfNx?= =?us-ascii?Q?Q/I/bAY4aA=3D=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: a8d1ea41-d04e-45ae-4a0c-08de86aa91c3 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Mar 2026 18:00:28.2839 (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: HdmOmU5jBDEutd2ZPTGdJN5QDDZl4EB5estb6Teni1ky3iCM65kKNAXO0IfGPbnB X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB6993 On 20 Mar 2026, at 10:22, Zi Yan wrote: > The added folio_split_race_test is a modified C port of the race condit= ion > test from [1]. The test creates shmem huge pages, where the main thread= > punches holes in the shmem to cause folio_split() in the kernel and > a set of 16 threads reads the shmem to cause filemap_get_entry() in the= > kernel. filemap_get_entry() reads the folio and xarray split by > folio_split() locklessly. The original test[2] is written in rust and u= ses > memfd (shmem backed). This C port uses shmem directly and use a single > process. > > Note: the initial rust to C conversion is done by Cursor. > > Link: https://lore.kernel.org/all/CAKNNEtw5_kZomhkugedKMPOG-sxs5Q5OLumW= JdiWXv+C9Yct0w@mail.gmail.com/ [1] > Link: https://github.com/dfinity/thp-madv-remove-test [2] > Signed-off-by: Bas van Dijk > Signed-off-by: Adam Bratschi-Kaye > Signed-off-by: Zi Yan > --- > From V3: > 1. fixed for loop stepping issue > 2. used PRIu64 instead of %zu for uint64_t. > > From V2: > 1. simplied the program by removing fork. > > From V1: > 1. added prctl(PR_SET_PDEATHSIG, SIGTERM) to avoid child looping > forever. > 2. removed page_idx % PUNCH_INTERVAL >=3D 0, since it is a nop. Added a= > comment. > 3. added a child process status check to prevent parent looping forever= > and record that as a failure. > 4. used ksft_exit_skip() instead of ksft_finished() when the program is= > not running as root. > 5. restored THP settings properly when the program exits abnormally. > tools/testing/selftests/mm/Makefile | 1 + > .../selftests/mm/folio_split_race_test.c | 293 ++++++++++++++++++= > tools/testing/selftests/mm/run_vmtests.sh | 2 + > 3 files changed, 296 insertions(+) > create mode 100644 tools/testing/selftests/mm/folio_split_race_test.c > Hi Andrew, The fixup below adds folio_split_race_test binary to .gitignore. Thank Lorenzo for pointing this out. =46rom bd164a7090c0e8b6e3013502c64c161214e38714 Mon Sep 17 00:00:00 2001 From: Zi Yan Date: Fri, 20 Mar 2026 13:56:04 -0400 Subject: [PATCH] git: add generated binary into gitignore Signed-off-by: Zi Yan --- tools/testing/selftests/mm/.gitignore | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/testing/selftests/mm/.gitignore b/tools/testing/selfte= sts/mm/.gitignore index 83ad9454dd9d1..b0c30c5ee9e30 100644 --- a/tools/testing/selftests/mm/.gitignore +++ b/tools/testing/selftests/mm/.gitignore @@ -61,3 +61,4 @@ guard-regions merge prctl_thp_disable rmap +folio_split_race_test -- = 2.51.0 Best Regards, Yan, Zi