From: Jakub Kicinski <kuba@kernel.org>
To: Yunsheng Lin <linyunsheng@huawei.com>
Cc: <davem@davemloft.net>, <pabeni@redhat.com>,
<netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
Lorenzo Bianconi <lorenzo@kernel.org>,
Alexander Duyck <alexander.duyck@gmail.com>,
Saeed Mahameed <saeedm@nvidia.com>,
Leon Romanovsky <leon@kernel.org>,
Eric Dumazet <edumazet@google.com>,
Jesper Dangaard Brouer <hawk@kernel.org>,
Ilias Apalodimas <ilias.apalodimas@linaro.org>,
<linux-rdma@vger.kernel.org>
Subject: Re: [PATCH net-next v4 1/5] page_pool: frag API support for 32-bit arch with 64-bit DMA
Date: Tue, 13 Jun 2023 21:09:06 -0700 [thread overview]
Message-ID: <20230613210906.42ea393e@kernel.org> (raw)
In-Reply-To: <20230612130256.4572-2-linyunsheng@huawei.com>
On Mon, 12 Jun 2023 21:02:52 +0800 Yunsheng Lin wrote:
> Currently page_pool_alloc_frag() is not supported in 32-bit
> arch with 64-bit DMA, which seems to be quite common, see
> [1], which means driver may need to handle it when using
> page_pool_alloc_frag() API.
>
> In order to simplify the driver's work for supporting page
> frag, this patch allows page_pool_alloc_frag() to call
> page_pool_alloc_pages() to return a big page frag without
it returns an entire (potentially compound) page, not a frag.
AFAICT
> page splitting because of overlap issue between pp_frag_count
> and dma_addr_upper in 'struct page' for those arches.
These two lines seem to belong in the first paragraph,
> As page_pool_create() with PP_FLAG_PAGE_FRAG is supported in
"is" -> "will now be"
> 32-bit arch with 64-bit DMA now, mlx5 calls page_pool_create()
> with PP_FLAG_PAGE_FRAG and manipulate the page->pp_frag_count
> directly using the page_pool_defrag_page(), so add a checking
> for it to aoivd writing to page->pp_frag_count that may not
> exist in some arch.
This paragraph needs some proof reading :(
> Note that it may aggravate truesize underestimate problem for
> skb as there is no page splitting for those pages, if driver
> need a accuate truesize, it may calculate that according to
accurate
> frag size, page order and PAGE_POOL_DMA_USE_PP_FRAG_COUNT
> being true or not. And we may provide a helper for that if it
> turns out to be helpful.
>
> 1. https://lore.kernel.org/all/20211117075652.58299-1-linyunsheng@huawei.com/
> + /* Return error here to avoid writing to page->pp_frag_count in
> + * mlx5e_page_release_fragmented() for page->pp_frag_count is
I don't see any direct access to pp_frag_count anywhere outside of
page_pool.h in net-next. PAGE_POOL_DMA_USE_PP_FRAG_COUNT sounds like
an internal flag, drivers shouldn't be looking at it, IMO.
next prev parent reply other threads:[~2023-06-14 4:09 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-12 13:02 [PATCH net-next v4 0/5] introduce page_pool_alloc() API Yunsheng Lin
2023-06-12 13:02 ` [PATCH net-next v4 1/5] page_pool: frag API support for 32-bit arch with 64-bit DMA Yunsheng Lin
2023-06-13 13:30 ` Alexander Lobakin
2023-06-14 3:36 ` Yunsheng Lin
2023-06-14 3:55 ` Jakub Kicinski
2023-06-14 10:52 ` Alexander Lobakin
2023-06-14 12:15 ` Yunsheng Lin
2023-06-14 12:42 ` Alexander Lobakin
2023-06-14 4:09 ` Jakub Kicinski [this message]
2023-06-14 11:42 ` Yunsheng Lin
2023-06-14 17:07 ` Jakub Kicinski
2023-06-15 7:29 ` Yunsheng Lin
2023-06-12 13:02 ` [PATCH net-next v4 2/5] page_pool: unify frag_count handling in page_pool_is_last_frag() Yunsheng Lin
2023-06-14 4:33 ` Jakub Kicinski
2023-06-14 11:55 ` Yunsheng Lin
2023-06-12 13:02 ` [PATCH net-next v4 3/5] page_pool: introduce page_pool_alloc() API Yunsheng Lin
2023-06-13 13:08 ` Alexander Lobakin
2023-06-13 13:11 ` Alexander Lobakin
2023-06-14 3:17 ` Yunsheng Lin
2023-06-12 13:02 ` [PATCH net-next v4 4/5] page_pool: remove PP_FLAG_PAGE_FRAG flag Yunsheng Lin
2023-06-14 17:19 ` Jakub Kicinski
2023-06-15 7:17 ` Yunsheng Lin
2023-06-15 16:51 ` Jakub Kicinski
2023-06-15 18:26 ` Alexander Duyck
2023-06-16 12:20 ` Yunsheng Lin
2023-06-16 15:01 ` Alexander Duyck
2023-06-16 18:59 ` Jesper Dangaard Brouer
2023-06-16 19:21 ` Jakub Kicinski
2023-06-16 20:42 ` Memory providers multiplexing (Was: [PATCH net-next v4 4/5] page_pool: remove PP_FLAG_PAGE_FRAG flag) Jesper Dangaard Brouer
2023-06-19 18:07 ` Jakub Kicinski
2023-06-20 15:12 ` Jesper Dangaard Brouer
2023-06-20 15:39 ` Jakub Kicinski
2023-06-30 2:27 ` Mina Almasry
2023-07-03 4:20 ` David Ahern
2023-07-03 6:22 ` Mina Almasry
2023-07-03 14:45 ` David Ahern
2023-07-03 17:13 ` Eric Dumazet
2023-07-03 17:23 ` David Ahern
2023-07-06 1:19 ` Mina Almasry
2023-07-03 17:15 ` Eric Dumazet
2023-07-03 17:25 ` David Ahern
2023-07-03 21:43 ` Jason Gunthorpe
2023-07-06 1:17 ` Mina Almasry
2023-07-10 17:44 ` Jason Gunthorpe
2023-07-10 23:02 ` Mina Almasry
2023-07-10 23:49 ` Jason Gunthorpe
2023-07-11 0:45 ` Mina Almasry
2023-07-11 13:11 ` Jason Gunthorpe
2023-07-11 17:24 ` Mina Almasry
2023-07-11 4:27 ` Christoph Hellwig
2023-07-11 4:59 ` Jakub Kicinski
2023-07-11 5:04 ` Christoph Hellwig
2023-07-11 12:05 ` Jason Gunthorpe
2023-07-11 16:00 ` Jakub Kicinski
2023-07-11 16:20 ` David Ahern
2023-07-11 16:32 ` Jakub Kicinski
2023-07-11 17:06 ` Mina Almasry
2023-07-11 20:39 ` Jakub Kicinski
2023-07-11 21:39 ` David Ahern
2023-07-12 3:42 ` Mina Almasry
2023-07-12 7:55 ` Christian König
2023-07-12 13:03 ` Jason Gunthorpe
2023-07-12 13:35 ` Christian König
2023-07-12 22:41 ` Mina Almasry
2023-07-12 13:01 ` Jason Gunthorpe
2023-07-12 20:16 ` Mina Almasry
2023-07-12 23:57 ` Jason Gunthorpe
2023-07-13 7:56 ` Christian König
2023-07-14 14:55 ` Mina Almasry
2023-07-14 15:18 ` David Ahern
2023-07-17 2:05 ` Mina Almasry
2023-07-17 3:08 ` David Ahern
2023-07-14 15:55 ` Jason Gunthorpe
2023-07-17 1:53 ` Mina Almasry
2023-07-24 14:56 ` Jesper Dangaard Brouer
2023-07-24 16:28 ` Jason Gunthorpe
2023-07-25 4:04 ` Mina Almasry
2023-07-26 17:36 ` Jesper Dangaard Brouer
2023-07-11 16:42 ` Jason Gunthorpe
2023-07-11 17:06 ` Jakub Kicinski
2023-07-11 18:52 ` Jason Gunthorpe
2023-07-11 20:34 ` Jakub Kicinski
2023-07-11 23:56 ` Jason Gunthorpe
2023-07-11 6:52 ` Dan Williams
2023-07-06 16:50 ` Jakub Kicinski
2023-06-17 12:19 ` [PATCH net-next v4 4/5] page_pool: remove PP_FLAG_PAGE_FRAG flag Yunsheng Lin
2023-06-15 13:59 ` Alexander Lobakin
2023-06-12 13:02 ` [PATCH net-next v4 5/5] page_pool: update document about frag API Yunsheng Lin
2023-06-14 4:40 ` Jakub Kicinski
2023-06-14 12:04 ` Yunsheng Lin
2023-06-14 16:56 ` Jakub Kicinski
2023-06-15 6:49 ` Yunsheng Lin
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