Re: [BUG 5.14] arm64/mm: dma memory mapping fails (in some cases)
From: David Hildenbrand <hidden>
Date: 2021-09-20 11:13:41
Also in:
linux-mm, lkml
On 18.09.21 07:18, Christoph Hellwig wrote:
On Sat, Sep 18, 2021 at 12:22:47AM +0300, Mike Rapoport wrote:quoted
I did some digging and it seems that the most "generic" way to check if a page is in RAM is page_is_ram(). It's not 100% bullet proof as it'll give false negatives for architectures that do not register "System RAM", but those are not using dma_map_resource() anyway and, apparently, never would.The downside of page_is_ram is that it looks really expensiv for something done at dma mapping time.
There would be ways to speed it up, similar to https://lkml.kernel.org/r/20210902160919.25683-2-david@redhat.com but the end result is still walking a list. Question would be, how much that overhead matters in practice. -- Thanks, David / dhildenb _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel