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Date:   Fri, 14 May 2021 15:49:00 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Logan Gunthorpe <logang@deltatee.com>
Cc:     linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
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Subject: Re: [PATCH v2 06/22] PCI/P2PDMA: Attempt to set map_type if it has
 not been set
Message-ID: <20210514134900.GA4715@lst.de>
References: <20210513223203.5542-1-logang@deltatee.com> <20210513223203.5542-7-logang@deltatee.com>
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On Thu, May 13, 2021 at 04:31:47PM -0600, Logan Gunthorpe wrote:
> Attempt to find the mapping type for P2PDMA pages on the first
> DMA map attempt if it has not been done ahead of time.
> 
> Previously, the mapping type was expected to be calculated ahead of
> time, but if pages are to come from userspace then there's no
> way to ensure the path was checked ahead of time.
> 
> With this change it's no longer invalid to call pci_p2pdma_map_sg()
> before the mapping type is calculated so drop the WARN_ON when that
> is the case.

Why?