From: Jason Gunthorpe <jgg@ziepe.ca>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: "Leon Romanovsky" <leon@kernel.org>,
"Pranjal Shrivastava" <praan@google.com>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Christian König" <christian.koenig@amd.com>,
"Alex Deucher" <alexander.deucher@amd.com>,
"David Airlie" <airlied@gmail.com>,
"Simona Vetter" <simona@ffwll.ch>,
"Gerd Hoffmann" <kraxel@redhat.com>,
"Dmitry Osipenko" <dmitry.osipenko@collabora.com>,
"Gurchetan Singh" <gurchetansingh@chromium.org>,
"Chia-I Wu" <olvaffe@gmail.com>,
"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
"Maxime Ripard" <mripard@kernel.org>,
"Thomas Zimmermann" <tzimmermann@suse.de>,
"Lucas De Marchi" <lucas.demarchi@intel.com>,
"Thomas Hellström" <thomas.hellstrom@linux.intel.com>,
"Vivi, Rodrigo" <rodrigo.vivi@intel.com>,
"Joerg Roedel" <joro@8bytes.org>, "Will Deacon" <will@kernel.org>,
"Robin Murphy" <robin.murphy@arm.com>,
"Felix Kuehling" <Felix.Kuehling@amd.com>,
"Alex Williamson" <alex@shazbot.org>,
"Ankit Agrawal" <ankita@nvidia.com>,
"Kasireddy, Vivek" <vivek.kasireddy@intel.com>,
"linux-media@vger.kernel.org" <linux-media@vger.kernel.org>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
"linaro-mm-sig@lists.linaro.org" <linaro-mm-sig@lists.linaro.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
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"virtualization@lists.linux.dev" <virtualization@lists.linux.dev>,
"intel-xe@lists.freedesktop.org" <intel-xe@lists.freedesktop.org>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
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Subject: Re: [PATCH v5 4/8] vfio: Wait for dma-buf invalidation to complete
Date: Thu, 29 Jan 2026 10:58:51 -0400 [thread overview]
Message-ID: <20260129145851.GE2307128@ziepe.ca> (raw)
In-Reply-To: <BN9PR11MB5276B99D4E8C6496B0C447888C9EA@BN9PR11MB5276.namprd11.prod.outlook.com>
On Thu, Jan 29, 2026 at 07:06:37AM +0000, Tian, Kevin wrote:
> Bear me if it's an ignorant question.
>
> The commit msg of patch6 says that VFIO doesn't tolerate unbounded
> wait, which is the reason behind the 2nd timeout wait here.
As far as I understand dmabuf design a fence wait should complete
eventually under kernel control, because these sleeps are
sprinkled all around the kernel today.
I suspect that is not actually true for every HW, probably something
like "shader programs can run forever technically".
We can argue if those cases should not report revocable either, but at
least this will work "correctly" even if it takes a huge amount of
time.
I wouldn't mind seeing a shorter timeout and print on the fence too
just in case.
Jason
next prev parent reply other threads:[~2026-01-29 14:58 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-24 19:14 [PATCH v5 0/8] dma-buf: Use revoke mechanism to invalidate shared buffers Leon Romanovsky
2026-01-24 19:14 ` [PATCH v5 1/8] dma-buf: Rename .move_notify() callback to a clearer identifier Leon Romanovsky
2026-01-24 19:14 ` [PATCH v5 2/8] dma-buf: Rename dma_buf_move_notify() to dma_buf_invalidate_mappings() Leon Romanovsky
2026-01-27 9:21 ` Christian König
2026-01-24 19:14 ` [PATCH v5 3/8] dma-buf: Always build with DMABUF_MOVE_NOTIFY Leon Romanovsky
2026-01-27 9:26 ` Christian König
2026-01-27 9:58 ` Leon Romanovsky
2026-01-27 10:02 ` Christian König
2026-01-27 11:42 ` Leon Romanovsky
2026-01-27 20:45 ` Leon Romanovsky
2026-01-30 7:00 ` Leon Romanovsky
2026-01-24 19:14 ` [PATCH v5 4/8] vfio: Wait for dma-buf invalidation to complete Leon Romanovsky
2026-01-26 20:53 ` Pranjal Shrivastava
2026-01-27 8:58 ` Leon Romanovsky
2026-01-27 16:27 ` Jason Gunthorpe
2026-01-29 7:06 ` Tian, Kevin
2026-01-29 7:33 ` Leon Romanovsky
2026-01-29 8:13 ` Tian, Kevin
2026-01-29 8:41 ` Leon Romanovsky
2026-01-29 21:04 ` Alex Williamson
2026-01-30 3:10 ` Tian, Kevin
2026-01-29 14:58 ` Jason Gunthorpe [this message]
2026-01-30 3:12 ` Tian, Kevin
2026-01-30 5:43 ` Mauro Carvalho Chehab
2026-01-30 5:48 ` Tian, Kevin
2026-01-30 8:46 ` Christian König
2026-01-30 8:30 ` Christian König
2026-01-30 13:01 ` Leon Romanovsky
2026-01-30 13:21 ` Christian König
2026-01-30 13:31 ` Leon Romanovsky
2026-01-30 13:56 ` Jason Gunthorpe
2026-01-30 14:11 ` Christian König
2026-01-30 14:44 ` Jason Gunthorpe
2026-02-02 8:42 ` Christian König
2026-02-02 15:12 ` Jason Gunthorpe
2026-02-02 15:21 ` Christian König
2026-02-02 15:55 ` Jason Gunthorpe
2026-01-24 19:14 ` [PATCH v5 5/8] dma-buf: Make .invalidate_mapping() truly optional Leon Romanovsky
2026-01-30 8:30 ` Christian König
2026-01-30 12:55 ` Leon Romanovsky
2026-01-24 19:14 ` [PATCH v5 6/8] dma-buf: Add dma_buf_attach_revocable() Leon Romanovsky
2026-01-26 20:38 ` Pranjal Shrivastava
2026-01-26 21:01 ` Jason Gunthorpe
2026-01-30 8:43 ` Christian König
2026-01-30 14:00 ` Jason Gunthorpe
2026-01-24 19:14 ` [PATCH v5 7/8] vfio: Permit VFIO to work with pinned importers Leon Romanovsky
2026-01-29 21:04 ` Alex Williamson
2026-01-30 3:14 ` Tian, Kevin
2026-01-24 19:14 ` [PATCH v5 8/8] iommufd: Add dma_buf_pin() Leon Romanovsky
2026-01-29 7:08 ` Tian, Kevin
2026-01-30 0:17 ` Jason Gunthorpe
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