From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 15 Nov 2021 10:53:12 -0800 From: Christoph Hellwig Subject: Re: [PATCH net-next v6] page_pool: disable dma mapping support for 32-bit arch with 64-bit DMA Message-ID: References: <20211013091920.1106-1-linyunsheng@huawei.com> <1090744a-3de6-1dc2-5efe-b7caae45223a@huawei.com> <644e10ca-87b8-b553-db96-984c0b2c6da1@collabora.com> <93173400-1d37-09ed-57ef-931550b5a582@huawei.com> MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=us-ascii Content-Disposition: inline List-ID: To: Ilias Apalodimas Cc: Christoph Hellwig , Yunsheng Lin , Guillaume Tucker , davem@davemloft.net, kuba@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linuxarm@openeuler.org, hawk@kernel.org, akpm@linux-foundation.org, peterz@infradead.org, will@kernel.org, jhubbard@nvidia.com, yuzhao@google.com, mcroce@microsoft.com, fenghua.yu@intel.com, feng.tang@intel.com, jgg@ziepe.ca, aarcange@redhat.com, guro@fb.com, "kernelci@groups.io" On Mon, Nov 15, 2021 at 08:48:30PM +0200, Ilias Apalodimas wrote: > page_pool (the API in question), apart from allocating memory can manage > the mappings for you. However while doing so it stores some parts (incl > the dma addr) in struct page. The code in there could be simplified if > we skipped support of the 'mapping' feature for 32-bit architectures with > 64-bit DMA. We thought no driver was using the mapping feature (on 32bits) > and cleaned up that part, but apparently we missed > '32-bit -- LPAE -- page pool manages DMA mappings' It is a very common configuration on various architectures, so I fear you'll have to support it and undo the cleanup.