Re: [BUG 5.14] arm64/mm: dma memory mapping fails (in some cases)
From: Mike Rapoport <rppt@kernel.org>
Date: 2021-09-22 07:22:40
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linux-mm, lkml
On Tue, Sep 21, 2021 at 05:38:05PM +0200, Christoph Hellwig wrote:
On Tue, Sep 21, 2021 at 12:34:10PM +0300, Mike Rapoport wrote:quoted
quoted
It doesn't create any new mappings. The only real issue is that it does the wrong thing for RAM in a way that might not be noticed on simple (x86/PC) platforms.But if the mapping request was rejected by devm_ioremap_resource() because of an attempt to map RAM, why we would get to dma_map_resource() at all?dma_map_resource takes a phys_addr_t that could come from anywhere.
Right, but it's not different from, say, dma_map_page_attrs() that can get a struct page from anywhere and there is no actual memory for that struct page at all. Do you suggest add a check that that struct page is backed by memory in dma_map_page_attrs() as well? -- Sincerely yours, Mike. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel