From: Arnd Bergmann <arnd@kernel.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>,
Grygorii Strashko <grygorii.strashko@ti.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Ilias Apalodimas <ilias.apalodimas@linaro.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
David Laight <David.Laight@aculab.com>,
Matteo Croce <mcroce@linux.microsoft.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Christoph Hellwig <hch@lst.de>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 1/1] mm: Fix struct page layout on 32-bit systems
Date: Sat, 17 Apr 2021 12:31:37 +0200 [thread overview]
Message-ID: <CAK8P3a2dekzohOrHpLq6yyuaoyC4UOxxucu6kX2oddeq5Jdqfg@mail.gmail.com> (raw)
In-Reply-To: <20210416152755.GL2531743@casper.infradead.org>
On Fri, Apr 16, 2021 at 5:27 PM Matthew Wilcox <willy@infradead.org> wrote:
> diff --git a/include/net/page_pool.h b/include/net/page_pool.h
> index b5b195305346..db7c7020746a 100644
> --- a/include/net/page_pool.h
> +++ b/include/net/page_pool.h
> @@ -198,7 +198,17 @@ static inline void page_pool_recycle_direct(struct page_pool *pool,
>
> static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
> {
> - return page->dma_addr;
> + dma_addr_t ret = page->dma_addr[0];
> + if (sizeof(dma_addr_t) > sizeof(unsigned long))
> + ret |= (dma_addr_t)page->dma_addr[1] << 32;
> + return ret;
> +}
Have you considered using a PFN type address here? I suspect you
can prove that shifting the DMA address by PAGE_BITS would
make it fit into an 'unsigned long' on all 32-bit architectures with
64-bit dma_addr_t. This requires that page->dma_addr to be
page aligned, as well as fit into 44 bits. I recently went through the
maximum address space per architecture to define a
MAX_POSSIBLE_PHYSMEM_BITS, and none of them have more than
40 here, presumably the same is true for dma address space.
Arnd
next prev parent reply other threads:[~2021-04-17 10:31 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-10 20:52 [PATCH 0/1] Fix struct page layout on 32-bit systems Matthew Wilcox (Oracle)
2021-04-10 20:52 ` [PATCH 1/1] mm: " Matthew Wilcox (Oracle)
2021-04-11 9:43 ` Jesper Dangaard Brouer
2021-04-11 10:33 ` Matthew Wilcox
2021-04-12 1:15 ` Matthew Wilcox
2021-04-14 8:10 ` Jesper Dangaard Brouer
2021-04-14 11:50 ` Matthew Wilcox
2021-04-14 11:56 ` Ilias Apalodimas
2021-04-14 15:52 ` David Laight
2021-04-14 19:13 ` Jesper Dangaard Brouer
2021-04-14 21:35 ` Matthew Wilcox
2021-04-14 21:56 ` David Laight
2021-04-15 18:08 ` Jesper Dangaard Brouer
2021-04-15 18:21 ` Matthew Wilcox
2021-04-15 21:11 ` David Laight
2021-04-15 22:22 ` Matthew Wilcox
2021-04-16 7:32 ` David Laight
2021-04-16 11:05 ` Matthew Wilcox
2021-04-16 15:27 ` Matthew Wilcox
2021-04-16 17:08 ` Jesper Dangaard Brouer
2021-04-17 3:19 ` Matthew Wilcox
2021-04-17 10:31 ` Arnd Bergmann [this message]
2021-04-17 13:56 ` Matthew Wilcox
2021-04-17 17:30 ` Arnd Bergmann
2021-04-17 10:59 ` David Laight
2021-04-19 6:34 ` Christoph Hellwig
2021-04-19 7:15 ` Ilias Apalodimas
2021-04-12 18:23 ` Matthew Wilcox
2021-04-13 8:21 ` David Laight
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