From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Matthew Rosato <mjrosato@linux.ibm.com>,
cohuck@redhat.com, borntraeger@linux.ibm.com,
jjherne@linux.ibm.com, akrowiak@linux.ibm.com,
pasic@linux.ibm.com, zhenyuw@linux.intel.com,
zhi.a.wang@intel.com, hch@infradead.org,
intel-gfx@lists.freedesktop.org,
intel-gvt-dev@lists.freedesktop.org, linux-s390@vger.kernel.org,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Kevin Tian <kevin.tian@intel.com>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v3 1/1] vfio: remove VFIO_GROUP_NOTIFY_SET_KVM
Date: Thu, 5 Jan 2023 19:34:30 -0400 [thread overview]
Message-ID: <Y7dehnZSC6ukNxKU@nvidia.com> (raw)
In-Reply-To: <20230105150930.6ee65182.alex.williamson@redhat.com>
On Thu, Jan 05, 2023 at 03:09:30PM -0700, Alex Williamson wrote:
> On Thu, 19 May 2022 14:33:11 -0400
> Matthew Rosato <mjrosato@linux.ibm.com> wrote:
>
> > Rather than relying on a notifier for associating the KVM with
> > the group, let's assume that the association has already been
> > made prior to device_open. The first time a device is opened
> > associate the group KVM with the device.
> >
> > This fixes a user-triggerable oops in GVT.
>
> It seems this has traded an oops for a deadlock, which still exists
> today in both GVT-g and vfio-ap. These are the only vfio drivers that
> care about kvm, so they make use of kvm_{get,put}_kvm(), where the
> latter is called by their .close_device() callbacks.
Bleck
It is pretty common to run the final part of 'put' from a workqueue
specifically to avoid stuff like this, eg fput does it
Maybe that is the simplest?
Jason
next prev parent reply other threads:[~2023-01-05 23:34 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-19 18:33 [PATCH v3 0/1] vfio: remove VFIO_GROUP_NOTIFY_SET_KVM Matthew Rosato
2022-05-19 18:33 ` [PATCH v3 1/1] " Matthew Rosato
2022-05-20 5:33 ` Christoph Hellwig
2022-05-20 13:36 ` Jason Gunthorpe
2022-05-20 13:56 ` Tony Krowiak
2022-05-20 14:09 ` Matthew Rosato
2022-05-20 20:59 ` Tony Krowiak
2022-05-23 16:41 ` Alex Williamson
2022-05-24 11:39 ` Wang, Zhi A
2023-01-05 22:09 ` Alex Williamson
2023-01-05 23:34 ` Jason Gunthorpe [this message]
2023-01-06 0:16 ` Matthew Rosato
2023-01-06 0:32 ` Jason Gunthorpe
2023-01-06 1:03 ` Matthew Rosato
2023-01-06 14:29 ` Jason Gunthorpe
2022-05-24 16:07 ` [PATCH v3 0/1] " Alex Williamson
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