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X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Jun 2025 03:46:07.3755 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 3494be12-3c31-402b-0353-08dda89a7f8a X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d;Ip=[4.158.2.129];Helo=[outbound-uk1.az.dlp.m.darktrace.com] X-MS-Exchange-CrossTenant-AuthSource: AM4PEPF00025F99.EURPRD83.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DB9PR08MB10377 X-Rspam-User: X-Rspamd-Queue-Id: 8DD7618000C X-Stat-Signature: 5c1cei97yjzauwmwhteu9mnu331k177y X-Rspamd-Server: rspam04 X-HE-Tag: 1749613572-451441 X-HE-Meta: U2FsdGVkX18PvH9Tb5RAc5dp05WrZiD8T+6ZHHDjrMevHhvv13mNBO+GX2ehMQQuAtP0kWrvJpEqT5YZjc+xr1TtB37F/YsD6+M4LpeDaRodcAIaks1wraKm+9IcCh45ytTuxoMCljb7op9A4rn3bJSwbsz4LM/Cs0NFKfWZdcNQ+YyOaMj7M+bPhpPHfQmJBzZZ89vUdj9r/1Zl7qz3rX/d3XTl6Pxa+KFbO4Q3frUytUNbr+V4gwTjPzY0+8vBhIA65keEOFFpeT4CAbQFUVsfYGVfmkH4h6j/9fnhdDZGZ1IJ0sO+ZRzoJSsLCkkH5WHAlayLC3n4F2+nHXSGESL6Usn8Y3+e1epGewdMJkCnXS0DFv6xBRNAnr85g90gX+VsjXBQt5h1q4F5fwcuWACT80jslfjULD8twY0OzIWz2QFVSFPkuivJH6zhAGnyiQZ5ireVtEyoYlWuWU7haXAJosg27/yUgZ7+UPBjrFXLp+PH/eDxkeJC0jyj7i1Gy7ptXCGgYciLFm/K0+21m+Fx/64z1JJwW2X3JT6l8uk7i4B4wOzC4ZQnpwWM0uW/Bd4dfm7uOTGt7C5/BdmTenPMp7ClrA6zCM656w54YdwW/PVs9eervCldaPah/HBI3jzzzelZ9P2p1xqN5gjt0YzbI2IgTwIqmsw768Muu+z/fh3Ro+ckxuZzi+qIBaD5FC/32JIqQ2YExVn+Ltb5EzIRvLOhTAh94NZRnE8s6piWuQIcZOsY1xXS/HfQ10VdX5C0B2woV9XWztlaZWcKgUcYPAsNustFoKh3zhJ31M6W1GvT2JpvpjJAzzXOrJNzYT65i0YwBArLERQMY3M29A1uZdSqJ2km/N2YiH8CCxzYp09iHctptF26EKCXTLKhF3rltMaiiX5EOmcGWIGRhx9XWV0OC2bxtk/abEmkr9MY77lN/HRnvSVfM9RnY8s1PJ/5QQLSTQkqjSSFrsB 87cEbl34 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/06/25 6:57 pm, Lorenzo Stoakes wrote: > On Tue, Jun 10, 2025 at 03:24:16PM +0200, David Hildenbrand wrote: >> On 10.06.25 14:07, Lorenzo Stoakes wrote: >>> OK so I think the best solution here is to just update check_ops_valid(), which >>> was kind of sucky anyway (we check everywhere but walk_page_range_mm() to >>> enforce the install pte thing). >>> >>> Let's do something like: >>> >>> #define OPS_MAY_INSTALL_PTE (1<<0) >>> #define OPS_MAY_AVOID_LOCK (1<<1) >>> >>> and update check_ops_valid() to take a flags or maybe 'capabilities' field. >>> >>> Then check based on this e.g.: >>> >>> if (ops->install_pte && !(capabilities & OPS_MAY_INSTALL_PTE)) >>> return false; >>> >>> if (ops->walk_lock == PGWALK_NOLOCK && !(capabilities & OPS_MAY_AVOID_LOCK)) >>> return false; >>> >> Hm. I mean, we really only want to allow this lockless check for >> walk_kernel_page_table_range(), right? >> >> Having a walk_kernel_page_table_range_lockeless() might (or might not) be >> better, to really only special-case this specific path. > Agree completely, Dev - let's definitely do this. Makes sense. > >> So, I am wondering if we should further start splitting the >> kernel-page-table walker up from the mm walker, at least on the "entry" >> function for now. > How do you mean? > >> -- >> Cheers, >> >> David / dhildenb >>