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Date:   Wed, 29 Jun 2022 08:48:54 +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 v7 20/21] PCI/P2PDMA: Introduce pci_mmap_p2pmem()
Message-ID: <20220629064854.GD17576@lst.de>
References: <20220615161233.17527-1-logang@deltatee.com> <20220615161233.17527-21-logang@deltatee.com>
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On Wed, Jun 15, 2022 at 10:12:32AM -0600, Logan Gunthorpe wrote:
> A pseudo mount is used to allocate an inode for each PCI device. The
> inode's address_space is used in the file doing the mmap so that all
> VMAs are collected and can be unmapped if the PCI device is unbound.
> After unmapping, the VMAs are iterated through and their pages are
> put so the device can continue to be unbound. An active flag is used
> to signal to VMAs not to allocate any further P2P memory once the
> removal process starts. The flag is synchronized with concurrent
> access with an RCU lock.

Can't we come up with a way of doing this without all the pseudo-fs
garbagage?  I really hate all the overhead for that in the next
nvme patch as well.