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From: Jason Gunthorpe <jgg@nvidia.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Tony Krowiak <akrowiak@linux.ibm.com>,
	cohuck@redhat.com, pasic@linux.vnet.ibm.com,
	jjherne@linux.ibm.com, alex.williamson@redhat.com,
	kwankhede@nvidia.com, frankja@linux.ibm.com, david@redhat.com,
	imbrenda@linux.ibm.com, hca@linux.ibm.com,
	Vasily Gorbik <gor@linux.ibm.com>,
	linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 1/2] s390/vfio-ap: clean up mdev resources when remove callback invoked
Date: Mon, 21 Jun 2021 14:27:14 -0300	[thread overview]
Message-ID: <20210621172714.GS1002214@nvidia.com> (raw)
In-Reply-To: <e809be5b-0b24-34dc-1eae-82b58dc54545@de.ibm.com>

On Mon, Jun 21, 2021 at 06:04:54PM +0200, Christian Borntraeger wrote:
> 
> 
> On 21.06.21 17:57, Tony Krowiak wrote:
> > The mdev remove callback for the vfio_ap device driver bails out with
> > -EBUSY if the mdev is in use by a KVM guest (i.e., the KVM pointer in the
> > struct ap_matrix_mdev is not NULL). The intended purpose was
> > to prevent the mdev from being removed while in use. There are two
> > problems with this scenario:
> > 
> > 1. Returning a non-zero return code from the remove callback does not
> >     prevent the removal of the mdev.
> > 
> > 2. The KVM pointer in the struct ap_matrix_mdev will always be NULL because
> >     the remove callback will not get invoked until the mdev fd is closed.
> >     When the mdev fd is closed, the mdev release callback is invoked and
> >     clears the KVM pointer from the struct ap_matrix_mdev.
> > 
> > Let's go ahead and remove the check for KVM in the remove callback and
> > allow the cleanup of mdev resources to proceed.
> > 
> > Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> > Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> > Cc: stable@vger.kernel.org
> 
> This one is already queued on
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git/log/?h=fixes
> 
> Jason. Do you want this in stable? Then we should write a mail after
> merging.

It is fine as is, we are already at rc7, so long as it goes to some
tree for this merge window

Jason

  reply	other threads:[~2021-06-21 17:27 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-21 15:57 [PATCH v6 0/2] s390/vfio-ap: fix memory leak in mdev remove callback Tony Krowiak
2021-06-21 15:57 ` [PATCH v6 1/2] s390/vfio-ap: clean up mdev resources when remove callback invoked Tony Krowiak
2021-06-21 16:04   ` Christian Borntraeger
2021-06-21 17:27     ` Jason Gunthorpe [this message]
2021-06-21 15:57 ` [PATCH v6 2/2] s390/vfio-ap: r/w lock for PQAP interception handler function pointer Tony Krowiak
2021-06-30 15:18   ` Tony Krowiak
2021-07-01 15:25     ` Christian Borntraeger
2021-07-01 16:28       ` Tony Krowiak
2021-07-07 17:16       ` Tony Krowiak
2021-07-01 15:13   ` Tony Krowiak

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