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Miller" , Andreas Larsson , Arnd Bergmann , Greg Kroah-Hartman , Dan Williams , Vishal Verma , Dave Jiang , Nicolas Pitre , Muchun Song , Oscar Salvador , Konstantin Komarov , Baoquan He , Vivek Goyal , Dave Young , Tony Luck , Reinette Chatre , Dave Martin , James Morse , Alexander Viro , Christian Brauner , Jan Kara , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Hugh Dickins , Baolin Wang , Uladzislau Rezki , Dmitry Vyukov , Andrey Konovalov , Jann Horn , Pedro Falcato , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-csky@vger.kernel.org, linux-mips@vger.kernel.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-mm@kvack.org, ntfs3@lists.linux.dev, kexec@lists.infradead.org, kasan-dev@googlegroups.com Subject: Re: [PATCH 03/16] mm: add vma_desc_size(), vma_desc_pages() helpers Message-ID: <20250908155652.GE789684@nvidia.com> References: <20250908133224.GE616306@nvidia.com> <090675bd-cb18-4148-967b-52cca452e07b@lucifer.local> <20250908142011.GK616306@nvidia.com> <764d413a-43a3-4be2-99c4-616cd8cd3998@lucifer.local> <20250908151637.GM616306@nvidia.com> <8edb13fc-e58d-4480-8c94-c321da0f4d8e@redhat.com> <20250908153342.GA789684@nvidia.com> <365c1ec2-cda6-4d94-895c-b2a795101857@redhat.com> <3229ac90-943f-4574-a9b8-bd4f5fa6cf03@redhat.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?k2WGDM93thqz9g+3ndn+U7nRm8ZHL78l3QvtMK+nI0KQ6Vj38I/0wQrQ0YVp?= =?us-ascii?Q?qONw/0XjBQA7b5vEHWrqf459ST7YWjEfE6HUKFTibdeAJltejXniA3UdJ4O8?= =?us-ascii?Q?xe+nYP8ACkq8HFwWINThs1CaD5JfhRsTMzfWTqh1ycpoW7bg1QqBpM0wiXCg?= =?us-ascii?Q?XfoguX8KFMMFlW9M1VDs7iksK66+BhQ4PjbgILlIUDxfIR2DWRdW9NAtsqjS?= =?us-ascii?Q?D5qX4joV7G/Co0lQNv2LUzrQpPmqYOpZKBApVwYRCLPSWLvY7lbUAzP6zXps?= =?us-ascii?Q?zKnsIJCPIgzhhhRRwY0JcQN8ab/I7tia/Pp2te9C0tprEL3w183wklfFKLGY?= =?us-ascii?Q?8khxcfMb9RA75zbGSr/3mhFIsWts+VYcvIW3+1TwfYYMljJCB8alWhb8E3BP?= =?us-ascii?Q?y5JP0OTIuumMofmZe8puahtM5KS0V+dOx89e37mMlSLRlFS9We7cHpjN6cIw?= =?us-ascii?Q?wYFKGuxpjzhW1xYW7KXzgOUSqbpKhY94Z8d1epTIXREqDDH1DoyRh/Av8lwi?= =?us-ascii?Q?Sx28zNx44ZGjYbTOQdxyFLWaCT5LCUeZC3dRy4kZMJl0GZqJQxVBaUtkqjwv?= =?us-ascii?Q?xayz6eIIW8cvDV6flP77twnR7pyk2RZyY/vURyB3FAqGsem9E8pUH1VEyuGJ?= =?us-ascii?Q?1R6urMNAFxX0mRKDZhhf6BzvlG/Hy6MrBfUFy8d4GFYRww7zkw3lZsJm1gsq?= =?us-ascii?Q?Ttd79gNq2+gkWFjLdR/besbwg+DfxjsuwS0uX4DrbQ/WaZanawl83RqDdS8Z?= =?us-ascii?Q?dWqOE0cbV6D0yfYtJ0nyV/OYsKLyXOvirNtCfU1HluaiE7K9Um20GmMminj5?= =?us-ascii?Q?B8m7PjVhH1lhui/dCF3MdYD5U1WuOvbVDvXU5XwUHqyP9N0lphgbdxwoboRa?= =?us-ascii?Q?8MhV+xOpQ9X/ykDI0II140z0pr1o5xaaI20DglU+Rh0uhBCloHsz1bcQFYxw?= =?us-ascii?Q?XSFEgGLsHGHrvUpmFigV3e8fo5VPEoJqeGiRtqHVfNJ9J/y9eQxPcU5yBhf7?= =?us-ascii?Q?EPmlj3nTcJRjcjO7q8e2vK0FSkpuGabU3wTFZ4StHuuGvNYocRnulaZSfVCc?= =?us-ascii?Q?Cf4KWqC9p2Edi49vHYpe/IExXGAiQHcZ5JNV4xnK7QKegjj9czFKhXIoXq5V?= =?us-ascii?Q?sE6E7gB9WOWYWn3UhjPpa4o/mMwlwgxpGBCg4Pw+P2iAeaQvCVZl/qttPdDO?= =?us-ascii?Q?YZIwADW0F5A5LwNgv2QKmWBs4nn8P5vk+dKrYA/4JIixON4FVfIwaUctLFu1?= =?us-ascii?Q?yxOxguG56ulzXvw7QCpXpgpf8T/beW0p8SX5L17YI9IkiEJGA8enaqiWHwne?= =?us-ascii?Q?lgFfgc9oGF2MWaMGX1cq8FpYEy1cPGzLWKBbJN4MvJ0o9EnSePhrUhZMAky/?= =?us-ascii?Q?kLHnkYBxnc/rOYMwk0l74Ux3xoZLhR/YSD6918fgBmx9K9JEdL00+i7CXa9+?= =?us-ascii?Q?LhZNHSVJm/VTw3Y8OCV+VZ+V5BhhjSvI8WAE9SjQus6R5RJDe3IpgCElSHi2?= =?us-ascii?Q?+d1K4HMLV5quOGBmHrfrWHxvi1P83Cxo4cODx/XuZV7dLMMV7+lOknz/00oe?= =?us-ascii?Q?lXZ6oBRN4mIDlrWCBOk=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 5b19a764-0afe-48c1-f96f-08ddeef05496 X-MS-Exchange-CrossTenant-AuthSource: BL1PR12MB5753.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Sep 2025 15:56:53.7301 (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: zECQ/ducSeIa5E7VwCdAlvmSlct/BfMSN0JnP1VjTChk8XPai14GelVHKi02FYfh X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY5PR12MB6202 On Mon, Sep 08, 2025 at 05:50:18PM +0200, David Hildenbrand wrote: > So in practice there is indeed not a big difference between a private and > cow mapping. Right and most drivers just check SHARED. But if we are being documentative why they check shared is because the driver cannot tolerate COW. I think if someone is cargo culting a diver and sees 'vma_never_cowable' they will have a better understanding of the driver side issues. Driver's don't actually care about private vs shared, except this indirectly implies something about cow. Jason