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X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Oct 2024 21:57:21.5464 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: ff6dca29-d67e-40c0-b597-08dceef6ad57 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BL6PEPF0001AB77.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB7689 On 10/17/24 2:47 PM, David Hildenbrand wrote: > On 17.10.24 23:28, Alistair Popple wrote: >> David Hildenbrand writes: >>> On 16.10.24 22:22, John Hubbard wrote: ... >>>> +        if (rc != -EAGAIN && rc != 0) >>>> +            unpin_user_pages(pages, nr_pinned_pages); >>>> + >>>>        } while (rc == -EAGAIN); >>> >>> Wouldn't it be cleaner to simply have here after the loop (possibly >>> even after the memalloc_pin_restore()) >>> >>> if (rc) >>>     unpin_user_pages(pages, nr_pinned_pages); >>> >>> But maybe I am missing something. >> >> I initially thought the same thing but I'm not sure it is >> correct. Consider what happens when __get_user_pages_locked() fails >> earlier in the loop. In this case it will have bailed out of the loop >> with rc <= 0 but we shouldn't call unpin_user_pages(). doh. yes. Thanks for catching that, Alistair! I actually considered it during the first draft, too, but got tunnel vision during the review, sigh. > > Ah, I see what you mean, I primarily only stared at the diff. > > We should likely avoid using nr_pinned_pages as a temporary variable that > can hold an error value. > OK, I still want to defer all the pretty refactoring ideas into some future effort, so for now, let's just leave v1 alone except for fixing the typo in the comment, yes? I'll still send out a 2-patch series with that, plus a suitably modified fix for the memfd case too. thanks, -- John Hubbard