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received-spf: None (protection.outlook.com: mellanox.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: Vlg8j145DMCic0yKX8M55cA/znV95y7LwbgWTEb5V0oTNzuOES/RUEw7fJF0WGnLUVEIqwDfvihM07pkp5D8C8wv+fDuMbOIAY5Tr/WC4oLLgCPTRMhM6FwBFpEQKcXiFmFNvvLW0lujg0LxH0NahHY7lCRucgP/xZbi5asYTku5DxdDcC7xhRDbIm5E70dLwMHslGv2uFCatqbtiOfixIelAfH2M8TjHbqZecb6oFFuvwxXUJKsrpsHOserO/k3uXQ+2g9n48qS4EVHfiPA1k96zIv2RFAMyNUTpAphFVSQCuLoSR5M0JZpmJINt84y2MORaMNhJwUHtk288UHDafyP7KXTazzqSMKsk+on6hfTIcH2398HOD23XV89QnKtKFbrHmWnhtge7ijlxSP26PUFTkOLssKRTbmG9BG3GWg= x-ms-exchange-transport-forked: True Content-Type: text/plain; charset="iso-8859-1" Content-ID: <1695A1151C0F3641B6BBDBD97CAD2365@eurprd05.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: Mellanox.com X-MS-Exchange-CrossTenant-Network-Message-Id: a6dd676e-d353-45d8-2e8e-08d723116df6 X-MS-Exchange-CrossTenant-originalarrivaltime: 17 Aug 2019 12:50:06.3920 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: a652971c-7d2e-4d9b-a6a4-d149256f461b X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: EKbtjcdg48Acrsg7vuLj3RsaBb93XGMzGcoKoIlnd/brgbVOLdhA7UfwMUk7gN0gLJX7vy6ZDXTc7Kal2bGWHg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR05MB5311 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Aug 17, 2019 at 01:31:28PM +0200, Christoph Hellwig wrote: > On Fri, Aug 16, 2019 at 05:11:07PM +0000, Jason Gunthorpe wrote: > > - if (args->cpages) > > - migrate_vma_prepare(args); > > - if (args->cpages) > > - migrate_vma_unmap(args); > > + if (!args->cpages) > > + return 0; > > + > > + migrate_vma_prepare(args); > > + migrate_vma_unmap(args); >=20 > I don't think this is ok. Both migrate_vma_prepare and migrate_vma_unmap > can reduce args->cpages, including possibly to 0. Oh, yes, that was far too hasty on my part, I had assumed collect set the cpages. Thank you for checking Jason