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Howlett" , linux-kernel@vger.kernel.org, willy@infradead.org, linux-mm@kvack.org, mcgrof@kernel.org, gost.dev@samsung.com, Pankaj Raghav Subject: Re: [PATCH v2] huge_memory: return -EINVAL in folio split functions when THP is disabled Date: Thu, 04 Sep 2025 09:21:20 -0400 X-Mailer: MailMate (2.0r6272) Message-ID: <74886543-6038-4444-8E2F-3F3169171837@nvidia.com> In-Reply-To: <20250904095129.222316-1-kernel@pankajraghav.com> References: <20250904095129.222316-1-kernel@pankajraghav.com> Content-Type: text/plain X-ClientProxiedBy: BN9P223CA0021.NAMP223.PROD.OUTLOOK.COM (2603:10b6:408:10b::26) 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_|CH3PR12MB9122:EE_ X-MS-Office365-Filtering-Correlation-Id: 153265f5-48e9-4b06-c487-08ddebb5f176 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|366016|376014|7416014; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?zGSs7957Fkgafw9LqQBnbS0VTsJMCFnSvSZB9Oq4Lon/Wy60GzM/z/wrwjoS?= =?us-ascii?Q?E2fIUKzSqdfjlCXztyDrst3WtGpRYW8NYhxM67C5uhPGm6H+XWSbQJLfpl3S?= =?us-ascii?Q?FlXTG37wyevVYxzKcqkiHv1rbEiECrFvdmuWZNaNXDFIu6UPUufHDfYijacq?= =?us-ascii?Q?/788gUhUqOOSsxX04uniRiX35y5IVV7nk/5ygAlkXjsdIyh/3ZpAUPbpQTM+?= =?us-ascii?Q?5WIJr+bXC+1fpxCdtn/9cEUOyar6IglRXNa/epMhGCf1oWZZNb/qqRaAWVhh?= =?us-ascii?Q?KR+4clEHONqNMg6hWphB5R9qTmR+Q3Umr2cdbIByD0OJtF6HGWsV5aMcbcbz?= =?us-ascii?Q?Ac9eYrUY8xwoY8xdNPisyd3ucwZ/23/4yDZgU9dxmSYM66Ytaaz9txQwl3qK?= =?us-ascii?Q?Dnt8bXee4WUdGy7nlH3cEJ/E+3DUhcpxgd+UqXkWRW9O/byFYLz3BFxwO5gQ?= =?us-ascii?Q?PV+xz/GtyLa275/a2XgW6oaHAn2mnZOlO+r+EeY2w5eekXuQmxKwqMFM+wfH?= =?us-ascii?Q?hE6ybZ2Cy8S4t9uwZLpBLMcBXy9odkfFCZt/D8mHo4xQzmKsQAa9gfTbxtWE?= =?us-ascii?Q?/yZC1Q22BWWoIJB549ywxftKFYbWDza4mgBeb/2buz4A7Gvnc/CG3y0AlMUL?= =?us-ascii?Q?qYBgBmYarG5SEticMvNnoVxJRiuIWrgixMxfwte17lR6PtEoRJc46Xwyro3W?= =?us-ascii?Q?ZiGA/wCTRGHF3fJ3sMzdj9/phw0zAk8Z4QATJ7NuOq6hHIr2MxVB5GwBIU/q?= =?us-ascii?Q?MdLcInx5UptQAupP/acYfhFsEdXB0SD0Sq0igEpzv0IfDChKFSRRVgKGvney?= =?us-ascii?Q?ZTTxsRFzp69XsGCKN/JdI6eLTu0b+QC+fIW5224qP9tRkEgx6z+y0rNTFIue?= =?us-ascii?Q?JYGy4lMX6LTIHttR1jOZ2Uk+xsr7mOrKZpSKLNzv5PxmXJrOThxEU0zet7yv?= =?us-ascii?Q?nKZmN7PktWJHiptqYb2OA6wZPyOJP7uk/AokC2D/FSER9IhgDJwkXF0ows2q?= =?us-ascii?Q?VnYn4A680lKE54txk3hfLTf+JB1X+hq8yHl19PJAfU/6bx0NTwkw87Icf+TX?= =?us-ascii?Q?EFoLKU6p6m4tK01lP2Dm4Pxki5TFheWeoy286W+TOxCQXQs0h/R42Wbf08Dx?= =?us-ascii?Q?hiRbKsszMvj7sL3eiLtAfx21knL95ZJa0Y59sVTxs0RrhqE3hK0DhhA6sZwa?= =?us-ascii?Q?4dSxxIyV2e0GnFbLSDJx5g40LFprJqR4+xlq5nm8ITzpYc2i/7msXh8BrHqM?= =?us-ascii?Q?CELDAcYJ8RZKlLMVEJRTVF33DzuMZwVg6IlO0bYfdH/cDICSQ1PtNEVdfz9u?= =?us-ascii?Q?sgRW/onqSOaXRpf3uFWXnfaFsgox0uFF+TC2WzcRh1eDRXCCWTPlPL+BmDIU?= =?us-ascii?Q?nHqmETLv9gwNQQFtvMD/5jx1qBMFOqm80tLrJCTcZkMFfsdKlWPRxQassDsU?= =?us-ascii?Q?Nkx974YgW3eDPo7PaOgXQ+lEwD06mI1X9sxhYrf/lGpY50U/80cW82BmN4K5?= =?us-ascii?Q?vAO4ofUY+6RnkzvxorMVNoA7fm7w8bK1Dlqd0Napdcl2i37J+YSCMuEtWMJC?= =?us-ascii?Q?fvHpJqkzthwcF1uJJ3ux9wHM9xlmjQp3FB6nRkAo?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 153265f5-48e9-4b06-c487-08ddebb5f176 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Sep 2025 13:21:23.0791 (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: dnoF175FlP5Zsqx6Fb1a7FbsQ+rQo9mTRFwHT3o9oyIg6PdT8JsAmhpwRCbln9FT X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB9122 On 4 Sep 2025, at 5:51, Pankaj Raghav (Samsung) wrote: > From: Pankaj Raghav > > split_huge_page_to_list_[to_order](), split_huge_page() and > try_folio_split() return 0 on success and error codes on failure. > > When THP is disabled, these functions return 0 indicating success even > though an error code should be returned as it is not possible to split a > folio when THP is disabled. > > Make all these functions return -EINVAL to indicate failure instead of > 0. As large folios depend on CONFIG_THP, issue warning as this function > should not be called without a large folio. > > Signed-off-by: Pankaj Raghav > --- > This issue was discovered while experimenting enabling large folios > without THP and found that returning 0 in these functions is resulting in > undefined behavior in truncate operations. This change fixes the issue. > > include/linux/huge_mm.h | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > Acked-by: Zi Yan Best Regards, Yan, Zi