From: Jason Gunthorpe <jgg@nvidia.com>
To: "Kasireddy, Vivek" <vivek.kasireddy@intel.com>
Cc: David Hildenbrand <david@redhat.com>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Christoph Hellwig <hch@infradead.org>,
Daniel Vetter <daniel.vetter@ffwll.ch>,
Mike Kravetz <mike.kravetz@oracle.com>,
Hugh Dickins <hughd@google.com>, Peter Xu <peterx@redhat.com>,
Gerd Hoffmann <kraxel@redhat.com>,
"Kim, Dongwon" <dongwon.kim@intel.com>,
"Chang, Junxiao" <junxiao.chang@intel.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v7 3/6] mm/gup: Introduce memfd_pin_folios() for pinning memfd folios (v7)
Date: Wed, 13 Dec 2023 08:31:55 -0400 [thread overview]
Message-ID: <20231213123155.GQ3014157@nvidia.com> (raw)
In-Reply-To: <IA0PR11MB718554F149A09AD0E64B4F0AF88DA@IA0PR11MB7185.namprd11.prod.outlook.com>
On Wed, Dec 13, 2023 at 08:44:51AM +0000, Kasireddy, Vivek wrote:
> That is, populate a scatterlist with ubuf->pagecount number of entries,
> where each segment if of size PAGE_SIZE, in order to be consistent and
> support a wide variety of DMA importers that may not probably handle
> segments that are larger than PAGE_SIZE.
No! This is totally wrong, sg lists must aggregate up to the limits
specified in the struct device. We have importer helpers that do this
aggregation.
If some driver is working with a sglist and can't handle this it is
simply broken. Do not mess up core code to accomodate such things.
Jason
next prev parent reply other threads:[~2023-12-13 12:32 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-12 7:37 [PATCH v7 0/6] " Vivek Kasireddy
2023-12-12 7:37 ` [PATCH v7 1/6] udmabuf: Use vmf_insert_pfn and VM_PFNMAP for handling mmap Vivek Kasireddy
2023-12-12 7:37 ` [PATCH v7 2/6] udmabuf: Add back support for mapping hugetlb pages (v6) Vivek Kasireddy
2023-12-12 7:38 ` [PATCH v7 3/6] mm/gup: Introduce memfd_pin_folios() for pinning memfd folios (v7) Vivek Kasireddy
2023-12-12 12:13 ` David Hildenbrand
2023-12-13 8:44 ` Kasireddy, Vivek
2023-12-13 12:31 ` Jason Gunthorpe [this message]
2023-12-13 15:36 ` Christoph Hellwig
2023-12-13 17:06 ` Jason Gunthorpe
2023-12-13 15:15 ` David Hildenbrand
2023-12-12 13:21 ` kernel test robot
2023-12-12 15:27 ` kernel test robot
2023-12-12 7:38 ` [PATCH v7 4/6] udmabuf: Convert udmabuf driver to use folios Vivek Kasireddy
2023-12-13 18:00 ` Matthew Wilcox
2023-12-12 7:38 ` [PATCH v7 5/6] udmabuf: Pin the pages using memfd_pin_folios() API (v5) Vivek Kasireddy
2023-12-13 18:03 ` Matthew Wilcox
2023-12-12 7:38 ` [PATCH v7 6/6] selftests/dma-buf/udmabuf: Add tests to verify data after page migration Vivek Kasireddy
2023-12-12 12:15 ` [PATCH v7 0/6] mm/gup: Introduce memfd_pin_folios() for pinning memfd folios (v7) David Hildenbrand
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