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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?KzO3S9GUpnBOddxEfFNrIbWoFCieXEWJOxPMEYl3LjOgYjEMJ7yMBRtqunUu?= =?us-ascii?Q?sYtgnkWBOnKc/drXWnV9nwZ2/wXDCJTs3Uevkoqm9Sny8w4ifkX2kiQnXxeL?= =?us-ascii?Q?M7Fittdd78ggH8rQah4/b5D4+hgctM03m8ljSdvfrG4hVBgXQuKPx9skUfUI?= =?us-ascii?Q?DjkGuvo0znACJqJNMnduGXjA3FkpvmVGns6R+8//OIpts3O9y7Z3djfCTHdV?= =?us-ascii?Q?A2R394DIT9F6eBlmGm37KlgiMuDZZVHoO5omapNTf+/NXQQ2gwHHhSXAnDuU?= =?us-ascii?Q?2R4hGFwU29sPaxknm637s7/Svw6C2FRDNIah05c7Pk0T/wbZMC+q8ih3+cWQ?= =?us-ascii?Q?IWaSp4gjuU7JmORqwYwgkot/DHFQnaXH9BkTKSj7hQ1uxUiz4yVvJn23coNP?= =?us-ascii?Q?xT7PXJ0SSfNJ3hgFTt2y1pPpA9x94spCMg73c71DMguknyMBiBJpYJXtJKoa?= =?us-ascii?Q?2byvfY1jnL800OFVlml3V3h1mtrbGp5V33mnH1VyvFf8b/ztgl9fqTcD2uoA?= =?us-ascii?Q?BLILMGRJ/nXAhadaUlo90wZa6bMN9m93wQXaXo7pFLRxx7zKRfR4tBAV+ytN?= =?us-ascii?Q?k1ErNFxfSeFdQtLHrxJQuAouSndQIDvE7vIjiGVir3nViGAvpwUqw8DakVka?= =?us-ascii?Q?HmElfXizbEj2BDpXlGIgGDkpLVnlUFEbXL5oVRK8HnGkOB9XibO8Qc5O0wCF?= =?us-ascii?Q?GC9tib6XtS2VU+fNYL82m9QCmKM/zk0RYjS8W5tfHcBJV7nY3MMMV6NzVuDB?= =?us-ascii?Q?hiiLRzOmYgELVcY0uTpo0GHRVXhZNikjaEBtaCp7HNdaD1wZ15ngo7ocgUSk?= =?us-ascii?Q?bGgAYF5dGgYlrwbGwM28s8FC6UrN4p39GAYt7voJOUKLgIU0+wW0ocEb3AAu?= =?us-ascii?Q?CXx9Z1u9oOA1paNB0G04PmeHfKyGMNVOueDo9hm33dDRlqTdw86o3mHFaNjI?= =?us-ascii?Q?0a6eTxLgjpGlsdz5bSAQ2xYWJQNAefU+hacuPRZMdwXtJucu4hph0xzYGSct?= =?us-ascii?Q?CBrJX8Hlpb44q8WAuU/UywYU5oPka7mdZxZ5qDZhhBRhuWVUSR97tC6GCHKV?= =?us-ascii?Q?jSA884wRbgJNKO7bI80Yq3pEDrd4LKmmlPxKWwNovMTf6qK1kZkbncbBDtt+?= =?us-ascii?Q?hy2XVn4TBrPcGMPGphzoane9z6yqBhp3yPQxEgQ9LJ4rGS4JaFLvZ5xC5wHl?= =?us-ascii?Q?d5MFONoa7TKCW1kP+AJLdU0DoZQV6q6D+b/H9fG7kUEMYSvdxzr/m8RtdC+8?= =?us-ascii?Q?uBNK9AsaSVmSvVDas64bOzjI75PL3EhQQw2m1iWtL5+sRgLhNB2We24Jhl6X?= =?us-ascii?Q?hIZ+Ro5FlmmOWbd0HzyhZDfSTgrwwOMkC6tRFR0kDd9kmb8SpOHPcjt/V7EX?= =?us-ascii?Q?J40Bn0VPVPCZHO+/sDSI/pGNAwUoCx6lRnQEqTnbRlF4jp0XjxZ5+2pwKead?= =?us-ascii?Q?blA9cMy5tN6F99rlmFpMAmClcaifcrOyTO8vk+oo/KniNUyRGIW14IVNiAz/?= =?us-ascii?Q?xSSx0vlv7DXTG/jpx44cl6PihIVoPTe2MM/wFS3sjhDeOuV7k6Fw/J/LqYGg?= =?us-ascii?Q?PZB5WAB28arqU27YIqC7TMfNqWMt/iV5pMS4g0Iy?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 7a108c50-9d16-4e8f-a99c-08da9259eeb5 X-MS-Exchange-CrossTenant-AuthSource: MN2PR12MB4192.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Sep 2022 11:53:38.4281 (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: fWft2s+gHO30tnUY8w6ubCt9lItC3vvp9WqaDF05e+RUFPJa8UxJvDXxab2HR7OW X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB5741 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Sep 08, 2022 at 12:27:06PM -0700, Dan Williams wrote: > flag lets the fsdax core track when it has already dropped a page > reference, but still has use for things like memory-failure to > opportunistically use page->mapping on a 0-reference page. This is not straightforward, as discussed before the page->mapping is allowed to change while the refcount is zero, so there is no generic way to safely obtain a pointer to the address space from a 0 reference page. You'd have to pass the 0 reference page into a new pgmap operation which could obtain an appropriate internal lock to read page->mapping. > > I'm not sure what it has to do with normal_page? > > This thread is mainly about DAX slowly reinventing _mapcount that gets > managed in all the right places for a normal_page. Longer term I think > we either need to get back to the page-less DAX experiment and find a > way to unwind some of this page usage creep, or cut over to finally > making DAX-pages be normal pages and delete most of the special case > handling in fs/dax.c. I am open to discussing the former, but I think > the latter is more likely. I think the latter is inevitable at this point.. Jason