From: Andrew Morton <akpm@linux-foundation.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Christoph Hellwig <hch@lst.de>,
stable@vger.kernel.org, linux-nvdimm@lists.01.org
Subject: Re: [PATCH v2 1/4] mm: introduce get_user_pages_longterm
Date: Tue, 21 Nov 2017 15:05:01 -0800 [thread overview]
Message-ID: <20171121150501.d4d811a66444cb5c9cb85bf2@linux-foundation.org> (raw)
In-Reply-To: <151068939435.7446.13560129395419350737.stgit@dwillia2-desk3.amr.corp.intel.com>
On Tue, 14 Nov 2017 11:56:34 -0800 Dan Williams <dan.j.williams@intel.com> wrote:
> Until there is a solution to the dma-to-dax vs truncate problem it is
> not safe to allow long standing memory registrations against
> filesytem-dax vmas. Device-dax vmas do not have this problem and are
> explicitly allowed.
>
> This is temporary until a "memory registration with layout-lease"
> mechanism can be implemented for the affected sub-systems (RDMA and
> V4L2).
Sounds like that will be unpleasant. Do we really need it to be that
complex? Can we get away with simply failing the get_user_pages()
request? Or are there significant usecases for RDMA and V4L to play
with DAX memory?
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next prev parent reply other threads:[~2017-11-21 23:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-14 19:56 [PATCH v2 0/4] introduce get_user_pages_longterm() Dan Williams
2017-11-14 19:56 ` [PATCH v2 1/4] mm: introduce get_user_pages_longterm Dan Williams
2017-11-21 23:05 ` Andrew Morton [this message]
2017-11-21 23:26 ` Dan Williams
2017-11-21 23:11 ` Andrew Morton
2017-11-14 19:56 ` [PATCH v2 2/4] mm: fail get_vaddr_frames() for filesystem-dax mappings Dan Williams
2017-11-27 16:15 ` Jan Kara
2017-11-27 16:19 ` Dan Williams
2017-11-14 19:56 ` [PATCH v2 3/4] [media] v4l2: disable filesystem-dax mapping support Dan Williams
2017-11-27 16:17 ` Jan Kara
2017-11-14 19:56 ` [PATCH v2 4/4] IB/core: disable memory registration of fileystem-dax vmas Dan Williams
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