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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8cd81aa2eefsm376234385a.42.2026.03.09.11.04.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Mar 2026 11:04:46 -0700 (PDT) Date: Mon, 9 Mar 2026 14:04:44 -0400 From: Gregory Price To: Shivank Garg Cc: akpm@linux-foundation.org, david@kernel.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@kernel.org, willy@infradead.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, dave@stgolabs.net, Jonathan.Cameron@huawei.com, rkodsara@amd.com, vkoul@kernel.org, bharata@amd.com, sj@kernel.org, weixugc@google.com, dan.j.williams@intel.com, rientjes@google.com, xuezhengchu@huawei.com, yiannis@zptcorp.com, dave.hansen@intel.com, hannes@cmpxchg.org, jhubbard@nvidia.com, peterx@redhat.com, riel@surriel.com, shakeel.butt@linux.dev, stalexan@redhat.com, tj@kernel.org, nifan.cxl@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH v4 5/6] drivers/migrate_offload: add DMA batch copy driver (dcbm) Message-ID: References: <20260309120725.308854-3-shivankg@amd.com> <20260309120725.308854-14-shivankg@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260309120725.308854-14-shivankg@amd.com> X-Rspamd-Queue-Id: 12D544000B X-Stat-Signature: i14smpcy8bh4gdn8rxdr8u747ya9irdr X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1773079487-198936 X-HE-Meta: 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 SIHp6mGa R8aZB4pNZ72Wulk8lrI+WPv3PPRY8ycLehYYZvTdy4x5G8zNkxV10nv2FiSEjEDRrHtOCJaBmBJTc7m/L81Dx49DPg9+tBwIGFufRgysbdoi9NBxzalFEZ4OocVs4R8PWOehE9h1okFa5ybpPjhB/FWxszzZ0IO4v+A42QcKiUMWw0Pia6V4QGTxwPLVMFdits/uqdX9SExMimPlZPRr4ZefbKfDG0WROVYwgt2FzXQ2GIS4rAOqQX3TcOZZz7YVCfTlSr0d33QBLQ8y6X40S01R+0qIeq4O5pTqxsgzPvYFdynSWJtYnklT3IuRMdU2w0YTlrIpMALa4p8I7a0KBRBmJ4sZBQplhku8qTJ+Fr4nhAjP9zxx2IlyYSrl8561E6iuO1AV+0KooUPh0vrv+Ck39zyGxex68OOsJhxl7O3o/VUpRFq6buahpFYOg38weZxQA Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Mar 09, 2026 at 12:07:31PM +0000, Shivank Garg wrote: > diff --git a/drivers/migrate_offload/Kconfig b/drivers/migrate_offload/Kconfig > new file mode 100644 > index 000000000000..0bbaedbae4ad > --- /dev/null > +++ b/drivers/migrate_offload/Kconfig > @@ -0,0 +1,8 @@ > +config DCBM_DMA > + bool "DMA Core Batch Migrator" Should this be tri-state or is built-in the only valid state? > +static int setup_sg_tables(struct dma_work *work, struct list_head **src_pos, > + struct list_head **dst_pos, int nr) > +{ ... snip .. > + dev = dmaengine_get_dma_device(work->chan); > + if (!dev) { > + ret = -ENODEV; > + goto err_free_dst_table; > + } > + ret = dma_map_sgtable(dev, work->src_sgt, DMA_TO_DEVICE, > + DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_NO_KERNEL_MAPPING); > + if (ret) > + goto err_free_dst_table; > + ret = dma_map_sgtable(dev, work->dst_sgt, DMA_FROM_DEVICE, > + DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_NO_KERNEL_MAPPING); > + if (ret) > + goto err_unmap_src; > + > + if (work->src_sgt->nents != work->dst_sgt->nents) { > + ret = -EINVAL; > + goto err_unmap_dst; > + } Fairly new to dma space, but I thought the dma stuff could merge pages on iommu systems. Wouldn't this check hit fairly often? ~Gregory