| From | David Howells <> | Subject | Re: [PATCH v7 2/8] iov_iter: Add a function to extract a page list from an iterator | Date | Sat, 21 Jan 2023 13:30:47 +0000 |
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Christoph Hellwig <hch@infradead.org> wrote:
> On Fri, Jan 20, 2023 at 05:55:50PM +0000, David Howells wrote: > > (3) Any other sort of iterator. > > > > No refs or pins are obtained on the page, the assumption is made that > > the caller will manage page retention. ITER_ALLOW_P2PDMA is not > > permitted. > > The ITER_ALLOW_P2PDMA check here is fundamentally wrong and will > break things like io_uring to fixed buffers on NVMe. ITER_ALLOW_P2PDMA > should strictly increase the group of acceptable iters, it does must > not restrict anything.
So just drop the check? Or do I actually need to do something to the pages to make it work? If I understand the code correctly, it's not actually operable right now on any page that doesn't have an appropriately marked PTE.
David
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