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Miller" , Andreas Larsson , Arnd Bergmann , Greg Kroah-Hartman , Dan Williams , Vishal Verma , Dave Jiang , Nicolas Pitre , Muchun Song , Oscar Salvador , David Hildenbrand , 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 10/16] mm/hugetlb: update hugetlbfs to use mmap_prepare, mmap_complete Message-ID: <20250908135240.GI616306@nvidia.com> References: <346e2d1e768a2e5bf344c772cfbb0cd1d6f2fd15.1757329751.git.lorenzo.stoakes@oracle.com> <20250908131121.GA616306@nvidia.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-ClientProxiedBy: BL1P223CA0031.NAMP223.PROD.OUTLOOK.COM (2603:10b6:208:5b6::6) To PH7PR12MB5757.namprd12.prod.outlook.com (2603:10b6:510:1d0::13) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH7PR12MB5757:EE_|BL3PR12MB6403:EE_ X-MS-Office365-Filtering-Correlation-Id: 138b36b5-423c-4e7c-ad4f-08ddeedefb5d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|1800799024|366016; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?aPrRPhrFQjv3SfE4vSQ1NbAV019tcqU1qVXsxZxVNICd1JIWa9Btp6PgGwbY?= =?us-ascii?Q?j36QykEKmw3MbKP3Ir8gVskSI+m2kYL2ZcEXiY2sOU79fkH4EfjJBS3F/mv3?= =?us-ascii?Q?VYUiclUy9JnHBK47oK/0gw9zrYVXRdhh6vIFQiExf72Ih3BjLDiZ3leiEWG4?= =?us-ascii?Q?WkQnIvfWQqB3U7nKO/DlqrVtsRKpBXHEIrtAjlvnk/x5s5hHdh7DBwq20GVX?= =?us-ascii?Q?HwBN15CGALZzJIKD60c35HJsTI+G/XOojXyd3LyL7MtbGLCuQRYkAalMpLcT?= =?us-ascii?Q?Q8ibCYPKspIzXdSxvTahKz0cb4kXWBvGDRxva2ATE4u0lxrdOObNOEAS1vla?= =?us-ascii?Q?GCtqKnKYYFCPd+lJQueYHqsA+iM0RhedisUFnyTyKt/asdNCAQnw/1X321+h?= =?us-ascii?Q?HbY2HvPH7QuIH03RVCIchn96RmmkSCrvLKwoBcLcyJeCE0XPhuEK2ZKSbKW3?= =?us-ascii?Q?UFjNYVjfNo6QeMyU+T+LRS+fMgShvmtiGT/7cY+80MMGEq5D+PPgL7tlTj3z?= =?us-ascii?Q?It/aRP67rKnXJtUkJX0JYy7tbLbnIL2rWjI2ZwRGQS0rZmfoQanypALvjACI?= =?us-ascii?Q?V9Fe3B/0Lsubnrq0QAFfLDPivuxFPCk9jb37pReyWrvg+q+WXtbJT4DXVFoo?= =?us-ascii?Q?qqqnOFA3OhagjBS2f2Ng3wNk2zZfzE7YriqbGyt/svbmnpg+Lc3vRm/uvFB8?= =?us-ascii?Q?LG9Uvum84+nJtwxdIXtePgR9I07/EcqQY1Qd/pk6kghilneAW+H5/WcqjNis?= =?us-ascii?Q?Op0tGlqFGHj0+T35arH/scobiVwNMC0KnzY9S+efQ5LlFKmRz+3WJKohl6Pu?= =?us-ascii?Q?Zi50Yza8T20DTbZ7yG+4KZhG6YFr6U04FG5fc33TJI/0Kw+TQ+LJiXXuKsmm?= =?us-ascii?Q?MIDIK1toAP1q4dT96OytNZdQc0l5uej2WAg7NXZvbyI1sccsb+cFmXeWwtZC?= =?us-ascii?Q?u2KorS9mMIr9I79HriRS1gEfsg8EF8KjgjvqoiyB3tK/lqxa9Jzb5XO4TDtU?= =?us-ascii?Q?4IkMlJquopjhDZmBMM2hvs8+3Nqe7fJ3rBie9hk8fvmtM3qa8fVgfW3yOkuD?= =?us-ascii?Q?ljJWhUY03ETvH9oKM2LiFVWil/Xt3oSd3rl/vDatmpzG1bwN0HlIbM3v6S+U?= =?us-ascii?Q?Ag3VsTM8lcR/6GHNUUQjdpOuKqPNjW/NNTvO0vMAexwaIoF7QCe3a7WNBGxa?= =?us-ascii?Q?w7eabV20HzvHFTBlqKjgxFHExrg2y/MqLHvp6I90bPqSVikQ/khp4XNOM4QN?= =?us-ascii?Q?pO+Meeozw/5+owDbiZceaVM14wxfdGDvxVnxJT8oJj8PMHXDVV62kYxo/hLb?= =?us-ascii?Q?fL/ef68sYwHm1VDIuTT6T+3qN0g4CcMztQYwIWHKRyeSjvzdjFYMJAyxjPaF?= =?us-ascii?Q?XPJ+1ScS7MrwVA9FWzfvqcj07vGKTn4VbNR97NulhumgoZcCQgOQ/Sivun1K?= =?us-ascii?Q?uNAs/vGfivsRe1vgQ+FYXWkDlUjO8oR+LejuUpfUHTRcsA7yaHds9DPIUkh2?= =?us-ascii?Q?juqdzv/maaavn7RycNnVOSZq92hwhZd/qI8esCEfzrPJ6sABNCVK4Rhkt9es?= =?us-ascii?Q?4+KMaf++WgJ/M9H73NI=3D?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 138b36b5-423c-4e7c-ad4f-08ddeedefb5d X-MS-Exchange-CrossTenant-AuthSource: PH7PR12MB5757.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Sep 2025 13:52:42.5830 (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: B9qQ772z8XaykaPtdPYnP0aqwJ4R0lpVij/kI/kg6PbGH1JhimkgakmrVDSi4uWe X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL3PR12MB6403 On Mon, Sep 08, 2025 at 02:37:44PM +0100, Lorenzo Stoakes wrote: > On Mon, Sep 08, 2025 at 10:11:21AM -0300, Jason Gunthorpe wrote: > > On Mon, Sep 08, 2025 at 12:10:41PM +0100, Lorenzo Stoakes wrote: > > > @@ -151,20 +123,55 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma) > > > vm_flags |= VM_NORESERVE; > > > > > > if (hugetlb_reserve_pages(inode, > > > - vma->vm_pgoff >> huge_page_order(h), > > > - len >> huge_page_shift(h), vma, > > > - vm_flags) < 0) > > > + vma->vm_pgoff >> huge_page_order(h), > > > + len >> huge_page_shift(h), vma, > > > + vm_flags) < 0) { > > > > It was split like this because vma is passed here right? > > > > But hugetlb_reserve_pages() doesn't do much with the vma: > > > > hugetlb_vma_lock_alloc(vma); > > [..] > > vma->vm_private_data = vma_lock; > > > > Manipulates the private which should already exist in prepare: > > > > Check non-share a few times: > > > > if (!vma || vma->vm_flags & VM_MAYSHARE) { > > if (vma && !(vma->vm_flags & VM_MAYSHARE) && h_cg) { > > if (!vma || vma->vm_flags & VM_MAYSHARE) { > > > > And does this resv_map stuff: > > > > set_vma_resv_map(vma, resv_map); > > set_vma_resv_flags(vma, HPAGE_RESV_OWNER); > > [..] > > set_vma_private_data(vma, (unsigned long)map); > > > > Which is also just manipulating the private data. > > > > So it looks to me like it should be refactored so that > > hugetlb_reserve_pages() returns the priv pointer to set in the VMA > > instead of accepting vma as an argument. Maybe just pass in the desc > > instead? > > Well hugetlb_vma_lock_alloc() does: > > vma_lock->vma = vma; > > Which we cannot do in prepare. Okay, just doing that in commit would be appropriate then > This is checked in hugetlb_dup_vma_private(), and obviously desc is not a stable > pointer to be used for comparing anything. > > I'm also trying to do the minimal changes I can here, I'd rather not majorly > refactor things to suit this change if possible. It doesn't look like a bit refactor, pass vma desc into hugetlb_reserve_pages(), lift the vma_lock set out Jason