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Wed, 25 Aug 2021 13:09:26 +0000 Received: from BL0PR12MB5506.namprd12.prod.outlook.com ([fe80::1de1:52a9:cf66:f336]) by BL0PR12MB5506.namprd12.prod.outlook.com ([fe80::1de1:52a9:cf66:f336%8]) with mapi id 15.20.4436.024; Wed, 25 Aug 2021 13:09:26 +0000 Date: Wed, 25 Aug 2021 10:09:23 -0300 From: Jason Gunthorpe To: Maor Gottlieb Cc: dledford@redhat.com, hch@infradead.org, leonro@nvidia.com, aelior@marvell.com, daniel@ffwll.ch, airlied@linux.ie, dennis.dalessandro@cornelisnetworks.com, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com, linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, maarten.lankhorst@linux.intel.com, mripard@kernel.org, mkalderon@marvell.com, mike.marciniszyn@cornelisnetworks.com, mustafa.ismail@intel.com, rodrigo.vivi@intel.com, sroland@vmware.com, shiraz.saleem@intel.com, tzimmermann@suse.de, linux-graphics-maintainer@vmware.com, liweihang@huawei.com, liangwenpeng@huawei.com, yishaih@nvidia.com, zackr@vmware.com, zyjzyj2000@gmail.com Subject: Re: [PATCH rdma-next v4 2/3] lib/scatterlist: Fix wrong update of orig_nents Message-ID: <20210825130923.GF1721383@nvidia.com> References: <20210824142531.3877007-1-maorg@nvidia.com> <20210824142531.3877007-3-maorg@nvidia.com> <20210824191248.GY1721383@nvidia.com> <4f4a712a-71d4-ebac-48f2-766bfda61f1e@nvidia.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?QC2HKcf36c/s+oibZmTNtcA78lnYhG+ixkUirhDXmpwQTtH/KN1r6NH6U+aG?= =?us-ascii?Q?fzC5XRHvUdwsrxnRu9l0I8Oyf+0u+rulS2Kyixg+ca2opPrQvkTe0EEpJy6P?= =?us-ascii?Q?DGMZD0fWZO0eBNUEuVFuRlOoz4bcyO/9frir2EN/1uOyuu9F5V5NYW4rkbk/?= =?us-ascii?Q?2rj0ekGqFUHcd04+TvvYEZLgJV+2RwWa5VDiuk+N+epclIR9mI3B5ySVjG0a?= =?us-ascii?Q?c2LsJPbLqEPVOYUULYjs/AcNQXzaVSxAEj2Xe3U8AaGZm8ZkQNavwx0TliVH?= =?us-ascii?Q?6ujccgdYzYttUZOag/r/h3RdUZiBSMPlI2baQ1cNk1uKc6R21DvlPNpaGm+6?= =?us-ascii?Q?dz/BrBw1Re2aBWdpX6u0zqDI4eU3Klsc3Fs5dez2ou1A3dooqe3ZllEnyCjr?= =?us-ascii?Q?f0y0zL55vRMq2i/fZCB2A/NCQ6PdBtFjnAJQrC1KYt9ywgVOqJLRMjny00y7?= =?us-ascii?Q?hSskqmKpgwVCWLUO5KrsLGkUq+z3GVMkwhcmb5/Nk89Zlqz/N/nb24d7UeDH?= =?us-ascii?Q?GpUqlH/Cb36sPsfnOuilB+k8Ac11/IgP1xcvM7qvd8NdfVzT9sVGg7aFBhTu?= =?us-ascii?Q?OLTzVFiY/nJrPgYu+m5zKgvBd4G47lHzJNT2VMOwZ1ChsSWjXBiV1cJcvZBa?= =?us-ascii?Q?7pW2jtThGQq4tE7sEN4pvv/sdaZNcTm6gohK9bHQ1Qdffx7KwoMKCrgiePtp?= =?us-ascii?Q?SY5206Ui+f7ioobxrI6v/91tRBwOVVkMggDwxJIxv1lYEG171jxmIw4GD1mM?= =?us-ascii?Q?WuEVcsMzkTAREwqHrGeN2z7lPwP6Gdd42t35JCsqv4eodkbKiY5XcFADmJ+J?= =?us-ascii?Q?/j1weMIijyZXYhn8hfmGUPOdDP/wqADfkKCbyljj7Lk7HrDSonsAippQmtWw?= =?us-ascii?Q?UH8qBrd4O7v1evspt6vjy9BEMoj3Gj12WslnrrHHWn8R5bqrK5R0iwjiA0uU?= =?us-ascii?Q?MZg/k7m6di5jcVWjJe2+i2lPIjm/Lz3xjCgp4nCJzBGbbF0J5Bjr9OZOF1dR?= =?us-ascii?Q?m2iFx6NErYuxZaLMLOa8L/Qx219eCnEhnw98BPxw4tmRGzXkW/yb0tWoSmdm?= =?us-ascii?Q?y7qXa385YBEMqsXvTXdG/6xk2C7yB+U9hpboHdQ+E+PNa/lBQYJ9QBP9e9Cl?= =?us-ascii?Q?txsipn2Z9LEPXgcBDmTPRY9Rt7mlRBnBEVVopFKrThmGeBOnix1PagSEkevZ?= =?us-ascii?Q?wxRMTOSVQFnj+4UAc2PvueN1KKMW6SWP6x/onVx4gqlquxlsD8Yhf20wIDFR?= =?us-ascii?Q?H8uf+HiiPMz9qy8g7LqH8qDgsN2I5PGVWHHXtWfOGyzUsmru3Dpo9RS7z/fW?= =?us-ascii?Q?/RubLX9LjBwrpTQebIffZxPa?= X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-Network-Message-Id: 55eb86c5-7a5f-43a7-6dea-08d967c99025 X-MS-Exchange-CrossTenant-AuthSource: BL0PR12MB5506.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Aug 2021 13:09:26.0776 (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: fz3iXxxhA4MEAMAQUOoJSB5rK9bKG/Y6lGyZoDVOD3uwWD6ldZlS3LwmSUCos9yX X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5127 Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Wed, Aug 25, 2021 at 07:59:27AM +0300, Maor Gottlieb wrote: > > On 8/24/2021 10:12 PM, Jason Gunthorpe wrote: > > On Tue, Aug 24, 2021 at 05:25:30PM +0300, Maor Gottlieb wrote: > > > @@ -514,11 +531,13 @@ struct scatterlist *sg_alloc_append_table_from_pages(struct sg_table *sgt, > > > offset = 0; > > > cur_page = j; > > > } > > > - sgt->nents += added_nents; > > > + sgt_append->sgt.nents += added_nents; > > > + sgt_append->sgt.orig_nents = sgt_append->sgt.nents; > > > + sgt_append->prv = s; > > Why is nents being touched here? > > > > Shouldn't it just be > > > > sgt_append->sgt.orig_nents += added_nents; > > sgt_append->prv = s; > > > > ? > > In general yes, but all the sg_alloc_* functions update both > orig_nents and nents (to same value). May be drivers that pass nents > instead of orig_nents to dma_map_sg* (like umem did before this > patch set). So I prefer to set it here as well, also not to break > sg_alloc_table_from_pages_segment which use the same path. This kind > of change could be done very carefully next cycle for all > sg_alloc_*. Ok, interesting Jason