From: Haozhong Zhang <haozhong.zhang@intel.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-nvdimm@lists.01.org, Michal Hocko <mhocko@suse.com>,
Jan Kara <jack@suse.cz>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org, linux-mm@kvack.org,
Alex Williamson <alex.williamson@redhat.com>,
Gerd Rausch <gerd.rausch@oracle.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org,
kbuild test robot <fengguang.wu@intel.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v2 0/5] vfio, dax: prevent long term filesystem-dax pins and other fixes
Date: Fri, 23 Feb 2018 16:55:47 +0800 [thread overview]
Message-ID: <20180223085547.3kkbo5lbt3orkqqn@hz-desktop> (raw)
In-Reply-To: <151937026001.18973.12034171121582300402.stgit@dwillia2-desk3.amr.corp.intel.com>
On 02/22/18 23:17 -0800, Dan Williams wrote:
> Changes since v1 [1]:
>
> * Fix the detection of device-dax file instances in vma_is_fsdax().
> (Haozhong, Gerd)
>
> * Fix compile breakage in the FS_DAX=n and DEV_DAX=y case. (0day robot)
>
> [1]: https://lists.01.org/pipermail/linux-nvdimm/2018-February/014046.html
>
> ---
>
> The vfio interface, like RDMA, wants to setup long term (indefinite)
> pins of the pages backing an address range so that a guest or userspace
> driver can perform DMA to the with physical address. Given that this
> pinning may lead to filesystem operations deadlocking in the
> filesystem-dax case, the pinning request needs to be rejected.
>
> The longer term fix for vfio, RDMA, and any other long term pin user, is
> to provide a 'pin with lease' mechanism. Similar to the leases that are
> hold for pNFS RDMA layouts, this userspace lease gives the kernel a way
> to notify userspace that the block layout of the file is changing and
> the kernel is revoking access to pinned pages.
>
> ---
>
> Dan Williams (5):
> dax: fix vma_is_fsdax() helper
> dax: fix dax_mapping() definition in the FS_DAX=n + DEV_DAX=y case
> dax: fix S_DAX definition
> dax: short circuit vma_is_fsdax() in the CONFIG_FS_DAX=n case
> vfio: disable filesystem-dax page pinning
>
>
> drivers/vfio/vfio_iommu_type1.c | 18 +++++++++++++++---
> include/linux/dax.h | 9 ++++++---
> include/linux/fs.h | 6 ++++--
> 3 files changed, 25 insertions(+), 8 deletions(-)
Tested on QEMU with fs-dax and device-dax as vNVDIMM backends
respectively with vfio passthrough. The fs-dax case fails QEMU as
expected, and the device-dax case works normally now.
Tested-by: Haozhong Zhang <haozhong.zhang@intel.com>
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next prev parent reply other threads:[~2018-02-23 8:55 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-23 7:17 Dan Williams
2018-02-23 7:17 ` [PATCH v2 1/5] dax: fix vma_is_fsdax() helper Dan Williams
2018-02-23 7:17 ` [PATCH v2 2/5] dax: fix dax_mapping() definition in the FS_DAX=n + DEV_DAX=y case Dan Williams
2018-02-26 9:44 ` Jan Kara
2018-02-23 7:17 ` [PATCH v2 3/5] dax: fix S_DAX definition Dan Williams
2018-02-26 9:43 ` Jan Kara
2018-02-23 7:18 ` [PATCH v2 4/5] dax: short circuit vma_is_fsdax() in the CONFIG_FS_DAX=n case Dan Williams
2018-02-23 7:18 ` [PATCH v2 5/5] vfio: disable filesystem-dax page pinning Dan Williams
2018-02-23 8:55 ` Haozhong Zhang [this message]
2018-02-23 16:56 ` [PATCH v2 0/5] vfio, dax: prevent long term filesystem-dax pins and other fixes Dan Williams
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