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Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Jonathan Corbet , linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] docs: update THP documentation to clarify sysfs "never" setting Date: Mon, 21 Jul 2025 21:13:21 -0400 X-Mailer: MailMate (2.0r6272) Message-ID: In-Reply-To: <20250721155530.75944-1-lorenzo.stoakes@oracle.com> References: <20250721155530.75944-1-lorenzo.stoakes@oracle.com> Content-Type: text/plain X-ClientProxiedBy: BN9PR03CA0688.namprd03.prod.outlook.com (2603:10b6:408:10e::33) 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_|SA1PR12MB6917:EE_ X-MS-Office365-Filtering-Correlation-Id: b19d1ea5-2db7-4f00-4324-08ddc8bcf5b2 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|376014|7416014|1800799024|7053199007; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?DmgZuHRS7wnqLHn0LKQX4O88NSC86BIt9Cx3Ofsrm7McfT6DWzo005WVhxyF?= =?us-ascii?Q?L7K6qXAHe4I1qp4/w18B+BC4g98EhA7WnsAj29VjN8kVNDTK4fufzoAqIRkx?= =?us-ascii?Q?vHxUm5c6sQiDqDUED99x5e313oNC96b2TRA9ps8udtabgvMqcbilHA2SJAk9?= =?us-ascii?Q?rVrV0ds+RYQUGCgwZroue54s1c7CxL2/tg/+KYtYxXtcgmP8INh7IqSGtnjE?= =?us-ascii?Q?Ku7YSp/87XopCfAS54mmu1GNmmR7AbvhWDiOjW9Bgiq3ilTJyGIbHVnSCJk2?= =?us-ascii?Q?OAc1FJglATevv97IoEaS/EvvKLBY3jr/nHo6fiG7PdGzGPVtI9/EXNYRgolb?= =?us-ascii?Q?8FhDfmKYJ8ezrHfagJP7SD3/9LAfCgs64UdawBDEKP3Z05osfJcRpMIzAkd8?= =?us-ascii?Q?ajIxL+GsICFyqjz1FG65H7999Pchkbg+W9ym0dM1NpgTrGYsDkZ/4fAwZ+OF?= =?us-ascii?Q?5U2mWAB2U3vu0LzFg5ke7j4ZOKfOhbXqfPWw8+pENXdPSQZswJKjATqI5tYl?= =?us-ascii?Q?vvO/8m2NZCMnfgBLOB63BkSEofLz21e8idmB6lPIZU6xo5lcvrYToxi9x9Xo?= =?us-ascii?Q?K0xxv2OYt2wuGXB2ekOmEAqAwLJfvpW1HufB2tPFEf/H+uwwjt23OlerS3pz?= =?us-ascii?Q?b7CS0CVmntbpu+ebEOqI9Vt+KYDZOfT6HlNZcfwDevOwYNOIYzfQyn0JDnoQ?= =?us-ascii?Q?kH8WQh2uBzeUkz4mIuFcNid1r/uEbGVaLgVOHgAZL1pKJX0fQopC1GQBW6s9?= =?us-ascii?Q?CADNS5Pp+LhLNHwfVrX10D77jtf+DXZXpNVYmZGxglQaVIo1mawvT8grOx9i?= =?us-ascii?Q?361XN5zyGzeBY+nb3IwJ8jsFu08HS33gJrmbX1ese95LnzGA2mSJW+EVPrv7?= =?us-ascii?Q?qh2B8HcH1qAfPcFGSVFymFumQISFcPFcbALy9aLrZ+mH4pC6qtO4MJKDYMEV?= =?us-ascii?Q?2BOde4SNpLg6BG8Ge8MiMhDc+1H4FoB2YwcEy7f+WaApQdJFaao8Cu344pK9?= =?us-ascii?Q?e+5Td5+e4pTyJnzXf163oRMcALoY6Zt+wuK+SuVkgfNSgm4CX/iVa+xkegKQ?= =?us-ascii?Q?Qo1HqhGAvCAKOBHOXxSTvMBU7Uwjw/GrozMZxX9HVcR8u8CcrOUjjl8APQJC?= =?us-ascii?Q?0EXKVftNGwQqX64RPNCYAJ2O99k21v+c6zIZgSYq2N97WhGFGtoAG/kzg/c9?= =?us-ascii?Q?8YWDeBOCH903xzM6F7gJpz6eBD6rsWh8A6sUmq6KHqa5uEg7Be8nozPiRXhl?= =?us-ascii?Q?tP/e0h8IXvGBB59v9SgjHlJTZc/zmMkoN7wXqERaUa/c8yGQZCY0Qa8EDMPJ?= =?us-ascii?Q?6pkE7/I1hr5KANxvCX/saBTas2r3SROBW8WVB6x8U6kGLrNFwgkfKC4b2i0K?= =?us-ascii?Q?SARVinLonVQVYVojtrhb8Hpy1oI6WAYconC9se899pEQTrcxUzQEA/2ou4+z?= =?us-ascii?Q?v2ujC8Za/kFTChS9bZpTqM/a2yNHSpmRkcRuSlAmlLJI+TBp5Ts5H3PhFzjs?= =?us-ascii?Q?u7Z6YHKeopHhK80G6fxZlk3TxS2IMzsajge/TGNKat1vpvtqcMnDGgA8OvGo?= =?us-ascii?Q?iSwl1No6Qkgan3jUdyhYZZPVIJUGpPmC9W9bPruf?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: b19d1ea5-2db7-4f00-4324-08ddc8bcf5b2 X-MS-Exchange-CrossTenant-AuthSource: DS7PR12MB9473.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 Jul 2025 01:13:25.9417 (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: +BH/WbGSrjHuogXtP//aMj6ZM9pSwS6Rn+kAzj/9UwlRjv3HSJHP1z9KlpMEwP4c X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR12MB6917 On 21 Jul 2025, at 11:55, Lorenzo Stoakes wrote: > Rather confusingly, setting all Transparent Huge Page sysfs settings to > "never" does not in fact result in THP being globally disabled. > > Rather, it results in khugepaged being disabled, but one can still obtain > THP pages using madvise(..., MADV_COLLAPSE). > > This is something that has remained poorly documented for some time, and it > is likely the received wisdom of most users of THP that never does, in > fact, mean never. > > It is therefore important to highlight, very clearly, that this is not the > ase. > > Signed-off-by: Lorenzo Stoakes > --- > Documentation/admin-guide/mm/transhuge.rst | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > LGTM. Reviewed-by: Zi Yan Best Regards, Yan, Zi