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Date: Tue, 3 Nov 2026 09:09:33 +0100
From: Christoph Hellwig <hch@lst.de>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Luigi Rizzo <lrizzo@google.com>,
	"David Hildenbrand (Arm)" <david@kernel.org>,
	Luigi Rizzo <rizzo.unipi@gmail.com>, Joerg Roedel <joro@8bytes.org>,
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	Vlastimil Babka <vbabka@kernel.org>,
	"David S . Miller" <davem@davemloft.net>,
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	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J . Wysocki" <rafael@kernel.org>,
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	Harshitha Ramamurthy <hramamurthy@google.com>,
	Saeed Mahameed <saeedm@nvidia.com>,
	Tariq Toukan <tariqt@nvidia.com>,
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	Przemek Kitszel <przemyslaw.kitszel@intel.com>,
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	Pavan Chebbi <pavan.chebbi@broadcom.com>, iommu@lists.linux.dev,
	netdev@vger.kernel.org, linux-mm@kvack.org,
	driver-core@lists.linux.dev, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC: DMA_PMD 00/22] DMA_PMD: PMD_SIZE-backed IO buffer pools
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On Fri, Oct 23, 2026 at 11:50:23AM -0300, Jason Gunthorpe wrote:
> > Disk I/O is still potentially affected by the same problems
> > (cost if io mapping/unmapping, iotlb thrashing, bounce buffers
> > in confidential computing...)
> 
> The disk folks already have a proposal to address all of this using
> io_uring and preallocated buffers. I really doubt yet another version
> is going to be interesting there.

Huh?  If you mean the dma-buf I/O it doesn't really have anything
to do with disks, except that this is the first user.  The dma-buf
iovec can work for every ->read_iter/->write_iter consumer, and
should be adopted more broadly.  Including by networking instead of
their own totally weird different world.