From: Jason Gunthorpe <jgg@nvidia.com>
To: Anthony Krowiak <akrowiak@linux.ibm.com>
Cc: mjrosato@linux.ibm.com, david@redhat.com, farman@linux.ibm.com,
imbrenda@linux.ibm.com, linux-s390@vger.kernel.org,
Yi Liu <yi.l.liu@intel.com>,
kvm@vger.kernel.org, pasic@linux.ibm.com,
borntraeger@linux.ibm.com, intel-gfx@lists.freedesktop.org,
intel-gvt-dev@lists.freedesktop.org, frankja@linux.ibm.com,
jjherne@linux.ibm.com, pmorel@linux.ibm.com, seanjc@google.com,
cohuck@redhat.com, linux-kernel@vger.kernel.org,
pbonzini@redhat.com
Subject: Re: [Intel-gfx] [PATCH] kvm/vfio: Fix potential deadlock on vfio group_lock
Date: Tue, 31 Jan 2023 10:34:35 -0400 [thread overview]
Message-ID: <Y9km+xezgD4ovjDX@nvidia.com> (raw)
In-Reply-To: <67ec09bf-cb24-34e3-6ec4-1ae87b0738bd@linux.ibm.com>
On Tue, Jan 31, 2023 at 09:27:54AM -0500, Anthony Krowiak wrote:
> I encountered a lockdep splat while running some regression tests today (see
> below). I suspected it might be this patch so I reverted it, rebuilt the
> kernel and ran the regression tests again; this time, the test ran cleanly.
> It looks like this patch may not have fixed the problem for which it was
> intended. Here is the relevant dmesg output:
Well, it fixes the deadlock it intended to fix and created another one
:)
It means device drivers cannot obtain the kvm lock from their open
functions in this new model.
Why does ap need to touch kvm->lock? (via get_update_locks_for_kvm)
Maybe you should split that lock and have a dedicated apcb lock?
Jason
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@nvidia.com>
To: Anthony Krowiak <akrowiak@linux.ibm.com>
Cc: Yi Liu <yi.l.liu@intel.com>,
alex.williamson@redhat.com, pbonzini@redhat.com,
mjrosato@linux.ibm.com, kevin.tian@intel.com, cohuck@redhat.com,
farman@linux.ibm.com, pmorel@linux.ibm.com,
borntraeger@linux.ibm.com, frankja@linux.ibm.com,
imbrenda@linux.ibm.com, david@redhat.com, jjherne@linux.ibm.com,
pasic@linux.ibm.com, zhenyuw@linux.intel.com,
zhi.a.wang@intel.com, seanjc@google.com,
linux-s390@vger.kernel.org, kvm@vger.kernel.org,
intel-gvt-dev@lists.freedesktop.org,
intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kvm/vfio: Fix potential deadlock on vfio group_lock
Date: Tue, 31 Jan 2023 10:34:35 -0400 [thread overview]
Message-ID: <Y9km+xezgD4ovjDX@nvidia.com> (raw)
In-Reply-To: <67ec09bf-cb24-34e3-6ec4-1ae87b0738bd@linux.ibm.com>
On Tue, Jan 31, 2023 at 09:27:54AM -0500, Anthony Krowiak wrote:
> I encountered a lockdep splat while running some regression tests today (see
> below). I suspected it might be this patch so I reverted it, rebuilt the
> kernel and ran the regression tests again; this time, the test ran cleanly.
> It looks like this patch may not have fixed the problem for which it was
> intended. Here is the relevant dmesg output:
Well, it fixes the deadlock it intended to fix and created another one
:)
It means device drivers cannot obtain the kvm lock from their open
functions in this new model.
Why does ap need to touch kvm->lock? (via get_update_locks_for_kvm)
Maybe you should split that lock and have a dedicated apcb lock?
Jason
next prev parent reply other threads:[~2023-01-31 14:34 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-20 15:05 [Intel-gfx] [PATCH] kvm/vfio: Fix potential deadlock on vfio group_lock Yi Liu
2023-01-20 15:05 ` Yi Liu
2023-01-20 15:08 ` [Intel-gfx] " Liu, Yi L
2023-01-20 15:08 ` Liu, Yi L
2023-01-20 15:45 ` [Intel-gfx] " Matthew Rosato
2023-01-20 15:45 ` Matthew Rosato
2023-01-20 15:49 ` [Intel-gfx] " Alex Williamson
2023-01-20 15:49 ` Alex Williamson
2023-01-20 17:58 ` [Intel-gfx] " Alex Williamson
2023-01-20 17:58 ` Alex Williamson
2023-01-20 19:25 ` [Intel-gfx] ✓ Fi.CI.BAT: success for " Patchwork
2023-01-21 20:16 ` [Intel-gfx] ✓ Fi.CI.IGT: " Patchwork
2023-01-31 14:27 ` [Intel-gfx] [PATCH] " Anthony Krowiak
2023-01-31 14:27 ` Anthony Krowiak
2023-01-31 14:34 ` Jason Gunthorpe [this message]
2023-01-31 14:34 ` Jason Gunthorpe
2023-01-31 14:46 ` [Intel-gfx] " Anthony Krowiak
2023-01-31 14:46 ` Anthony Krowiak
2023-01-31 14:48 ` [Intel-gfx] " Jason Gunthorpe
2023-01-31 14:48 ` Jason Gunthorpe
2023-01-31 15:00 ` [Intel-gfx] " Matthew Rosato
2023-01-31 15:00 ` Matthew Rosato
2023-01-31 15:12 ` [Intel-gfx] " Jason Gunthorpe
2023-01-31 15:12 ` Jason Gunthorpe
2023-01-31 14:35 ` [Intel-gfx] " Matthew Rosato
2023-01-31 14:35 ` Matthew Rosato
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