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Date: Sat, 6 Jul 2024 08:26:04 +0200
From: Christoph Hellwig <hch@lst.de>
To: Chaitanya Kulkarni <chaitanyak@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>, Leon Romanovsky <leon@kernel.org>,
	Jens Axboe <axboe@kernel.dk>, Jason Gunthorpe <jgg@ziepe.ca>,
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	=?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>,
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Subject: Re: [RFC PATCH v1 00/18] Provide a new two step DMA API mapping API
Message-ID: <20240706062604.GA13874@lst.de>
References: <cover.1719909395.git.leon@kernel.org> <20240703054238.GA25366@lst.de> <20240703105253.GA95824@unreal> <20240703143530.GA30857@lst.de> <a7f1c69a-bbaf-4263-b2c2-3c92d65522c2@nvidia.com>
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On Fri, Jul 05, 2024 at 10:53:06PM +0000, Chaitanya Kulkarni wrote:
> I tried to reproduce this issue somehow it is not reproducible.
> 
> I'll try again on Leon's setup on my Saturday night, to fix that
> case.

It is passthrough I/O from userspace.  The address is not page aligned
as seen in the printk.  Forcing bounce buffering of all passthrough
I/O makes it go away.

The problem is the first mapped segment does not have to be aligned
and we're missing the code to places it at the aligned offset into
the IOVA space.