From: David Miller <davem@davemloft.net>
To: brouer@redhat.com
Cc: netdev@vger.kernel.org, linux-mm@kvack.org, toke@toke.dk,
ilias.apalodimas@linaro.org, willy@infradead.org,
saeedm@mellanox.com, alexander.duyck@gmail.com,
akpm@linux-foundation.org, mgorman@techsingularity.net,
tariqt@mellanox.com
Subject: Re: [net-next PATCH V3 0/3] Fix page_pool API and dma address storage
Date: Wed, 13 Feb 2019 22:02:38 -0800 (PST) [thread overview]
Message-ID: <20190213.220238.72067832020194055.davem@davemloft.net> (raw)
In-Reply-To: <155002290134.5597.6544755780651689517.stgit@firesoul>
From: Jesper Dangaard Brouer <brouer@redhat.com>
Date: Wed, 13 Feb 2019 02:55:34 +0100
> As pointed out by David Miller in [1] the current page_pool implementation
> stores dma_addr_t in page->private. This won't work on 32-bit platforms with
> 64-bit DMA addresses since the page->private is an unsigned long and the
> dma_addr_t a u64.
>
> Since no driver is yet using the DMA mapping capabilities of the API let's
> fix this by storing the information in 'struct page' and use that to store
> and retrieve DMA addresses from network drivers.
>
> As long as the addresses returned from dma_map_page() are aligned the first
> bit, used by the compound pages code should not be set.
>
> Ilias tested the first two patches on Espressobin driver mvneta, for which
> we have patches for using the DMA API of page_pool.
>
> [1]: https://lore.kernel.org/netdev/20181207.230655.1261252486319967024.davem@davemloft.net/
>
> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
> Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Series applied, thanks Jesper.
prev parent reply other threads:[~2019-02-14 6:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-13 1:55 [net-next PATCH V3 0/3] Fix page_pool API and dma address storage Jesper Dangaard Brouer
2019-02-13 1:55 ` [net-next PATCH V3 1/3] mm: add dma_addr_t to struct page Jesper Dangaard Brouer
2020-04-29 0:38 ` Kirill A. Shutemov
2020-04-29 1:54 ` Matthew Wilcox
2019-02-13 1:55 ` [net-next PATCH V3 2/3] net: page_pool: don't use page->private to store dma_addr_t Jesper Dangaard Brouer
2019-02-13 1:55 ` [net-next PATCH V3 3/3] page_pool: use DMA_ATTR_SKIP_CPU_SYNC for DMA mappings Jesper Dangaard Brouer
2019-02-14 6:02 ` David Miller [this message]
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