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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?drplbR4EtmIL+ztQE8yE4nrP9FsUJRsXdF5zlZ9bcK2tDl8RT6Enl7MSySbA?= =?us-ascii?Q?kcDGVWwAGhF2ICwgO7+p3CnzIKsgDZ8zhh9u/Wt2pYfSyIGOvNt/KakKde01?= =?us-ascii?Q?AbN9eRHKVL+ReE2qJWymA4Y2jsHaNXFnn8qBpX3botsbSTI3qUai2AIy0exh?= =?us-ascii?Q?qiEY8gETHRqAoKlq6wKDENRwnxl+fsxcaKwGfbEdQLlLk057BBw3xoW0FwYT?= =?us-ascii?Q?mR5d54fzC5vqlpODjk2elKHqvxs7BmsAeXgVzERDjJM0KridxaOpRJA/g3hz?= =?us-ascii?Q?RHPd7Tuw7F4XBoGwjrN7dH3Mb/XKx9XKB5+RsenKZItWsl7s74M3ihZ3I22u?= =?us-ascii?Q?iWjimBdkCc/EXJHAXNhSfGRVvSx4DAP2OSj3yxtrpTkUK2eREQWjIKZHDHwZ?= =?us-ascii?Q?vNmmmkWk71jgf/qeFCtHmyI0gY5FoBZAGv6yPx3NbWsYr6ppG4F8cXSsRjQN?= =?us-ascii?Q?8F1T7+l33WIlvlbm0yymaPff20JD9qIgBmbY9eY0MZvFr6bYIeorSSguUZQk?= =?us-ascii?Q?mmMa1mC4jLMVQ0q3Ey90OXyP2jA8QTFN81/FV4yDLZmnzaDXifDy12MSnv/M?= =?us-ascii?Q?4MSp7nH1EJ+0uXXKBGb+RGsHY7+60KQz9/ugkY9gS1TrkrVAgLzHhp+ciFIi?= =?us-ascii?Q?1zyfFA3AHmuNJeUxXLIFrsvFHvBSYHjegnUF3dZ1/ePGW7cxhAuOpi3t+kuv?= =?us-ascii?Q?15ieOOu4vima2jhaJd3j2WGXxpmlD5onWZqPEMAkcZyVP4axCbAsIieEiIMF?= =?us-ascii?Q?OsGy/nvcSczBO1ghh2vA2zIc6eUyIZa6MhfSg7GzZHdITiHyG7w9otR5OVtr?= =?us-ascii?Q?pkPusCb0rdqivwoQs+KVHnsvsECQPlWfhexPXZAg0nw3g2NsydVkvQbBPvq6?= =?us-ascii?Q?4qvj+WiIcE6v/75cet0rR3TUpF8QSYaynvO/2dcogvEdSwC56tfGBRn7AEDw?= =?us-ascii?Q?xPEd9cf/Bwt/iqGePFnZVdM5oyuL+YEVLpHX+cAtKZum6C5mNd96Kzx48niA?= =?us-ascii?Q?cxYkp5F1HlbF7GHRd78biYIAbidicbkFXu3Qm7FChfps5MCuDn+SW/5bAJf6?= =?us-ascii?Q?/vH7M19YD6j05QUEYNC2VK4MiOrg4yB7Iwfyz2Ddqic26xJlgkt/dNrVTLI5?= =?us-ascii?Q?WnfDXasT9xn9YYvCM0fvpWSj3wYUxj0eLq/KMSGLxIr/CDDHeX0Qyn2WdqQg?= =?us-ascii?Q?VxezroZeLBW1htJ1k9/nSsLRTFSsIfsvBjPcdswQat1lN52lBwuURCkjjwZ3?= =?us-ascii?Q?wXl0RQIjLU2c4rSsW+R2G48wz+rz15tjOQjG5zWb8QE6QpUsgigri901+k+4?= =?us-ascii?Q?M55c3RZSLS5qtgreYiH7yAO1QFSure3ltoP9BDfzN/dYi4NUGxkVlT9zR5AQ?= =?us-ascii?Q?lFwfB+xcFsKPL1U65cVbJKkfbbBul0HONG+66KLHUoBW0xcaDWN1lquaK7gv?= =?us-ascii?Q?nQdqnHyVdciX72Q1zChAVbQBTcqHZqCsKW1mkgoprAy7iIGzW3W6XbTxojpq?= =?us-ascii?Q?c40J3R1+ON1E1bNVFRdHyw/hhh+LuGp2zTZJxjngqvMLVpEZnY2CHqIcUAQ7?= =?us-ascii?Q?IuCXYBrPnzy34aSoBCgJEkLu6Bp150V1Y34X1yhr?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: acc28684-b6c3-4139-85b9-08ddaa9366c9 X-MS-Exchange-CrossTenant-AuthSource: CH3PR12MB8659.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Jun 2025 16:00:22.3762 (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: UU4OVI0mztj+dHKRRR8ki5V/Jpmh76+YRpF2v0Waoo7ZDgYwPeNFY/MTUOqV74Vu X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM3PR12MB9286 On Fri, Jun 13, 2025 at 11:13:58AM -0400, Peter Xu wrote: > > I didn't intuitively guess how it works or why there are two > > length/size arguments. It seems to have an exciting return code as > > well. > > > > I suppose size is the alignment target? Maybe rename the parameter too? > > Yes, when the kdoc is there it'll be more obvious. So far "size" is ok to > me, but if you have better suggestion please shoot - whatever I came up > with so far seems to be too long, and maybe not necessary when kdoc will be > available too. I would call it align not size > > For the purposes of VFIO do we need to be careful about math overflow here: > > > > loff_t off_end = off + len; > > loff_t off_align = round_up(off, size); > > > > ? > > IIUC the 1st one was covered by the latter check here: > > (off + len_pad) < off > > Indeed I didn't see what makes sure the 2nd won't overflow. I'm not sure the < tests are safe in this modern world. I would use the overflow helpers directly and remove the < overflow checks. > +/** > + * mm_get_unmapped_area_aligned - Allocate an aligned virtual address > + * @filp: file target of the mmap() request > + * @addr: hint address from mmap() request > + * @len: len of the mmap() request > + * @off: file offset of the mmap() request > + * @flags: flags of the mmap() request > + * @size: the size of alignment the caller requests Just "the alignment the caller requests" > + * @vm_flags: the vm_flags passed from get_unmapped_area() caller > + * > + * This function should normally be used by a driver's specific > + * get_unmapped_area() handler to provide a properly aligned virtual > + * address for a specific mmap() request. The caller should pass in most > + * of the parameters from the get_unmapped_area() request, but properly > + * specify @size as the alignment needed. .. "The function willl try to return a VMA starting address such that ret % size == 0" Jason