From: Christian Borntraeger <borntraeger@linux.ibm.com>
To: Jason Gunthorpe <jgg@nvidia.com>,
Matthew Rosato <mjrosato@linux.ibm.com>
Cc: Alex Williamson <alex.williamson@redhat.com>,
Tony Krowiak <akrowiak@linux.ibm.com>,
"Jason J . Herne" <jjherne@linux.ibm.com>,
Marc Hartmayer <mhartmay@linux.ibm.com>,
Eric Farman <farman@linux.ibm.com>,
Cornelia Huck <cohuck@redhat.com>,
kvm@vger.kernel.org, Qian Cai <cai@lca.pw>,
Joerg Roedel <jroedel@suse.de>,
Marek Szyprowski <m.szyprowski@samsung.com>,
linux-s390 <linux-s390@vger.kernel.org>
Subject: Re: [PATCH v2] vfio: Follow a strict lifetime for struct iommu_group
Date: Wed, 5 Oct 2022 16:00:41 +0200 [thread overview]
Message-ID: <bca44128-e550-e8e5-5d89-cd69307284f6@linux.ibm.com> (raw)
In-Reply-To: <Yz2NSDa3E6LpW1c5@nvidia.com>
Am 05.10.22 um 15:57 schrieb Jason Gunthorpe:
> On Wed, Oct 05, 2022 at 09:46:45AM -0400, Matthew Rosato wrote:
>
>
>> (again, with the follow-up applied) Besides the panic above I just
>> noticed there is also this warning that immediately precedes and is
>> perhaps more useful. Re: what triggers the WARN, both group->owner
>> and group->owner_cnt are already 0
>
> And this is after the 2nd try that fixes the locking?
>
> This shows that vfio_group_detach_container() is called twice (which
> was my guess), hoever this looks to be impossible as both calls are
> protected by 'if (group->container)' and the function NULL's
> group->container and it is all under the proper lock.
>
> My guess was that missing locking caused the two cases to race and
> trigger WARN, but the locking should fix that.
>
> So I'm at a loss, can you investigate a bit?
So where is your 2nd version (and what was the first). I only saw one fix.
next prev parent reply other threads:[~2022-10-05 14:00 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-23 0:06 [PATCH v2] vfio: Follow a strict lifetime for struct iommu_group Jason Gunthorpe
2022-09-26 17:03 ` Matthew Rosato
2022-09-27 20:05 ` Alex Williamson
2022-10-04 15:19 ` Christian Borntraeger
2022-10-04 15:40 ` Jason Gunthorpe
2022-10-04 15:44 ` Christian Borntraeger
2022-10-04 16:28 ` Jason Gunthorpe
2022-10-04 17:15 ` Christian Borntraeger
2022-10-04 17:22 ` Jason Gunthorpe
2022-10-04 17:36 ` Christian Borntraeger
2022-10-04 17:48 ` Christian Borntraeger
2022-10-04 18:22 ` Matthew Rosato
2022-10-04 18:56 ` Eric Farman
2022-10-05 13:46 ` Matthew Rosato
2022-10-05 13:57 ` Jason Gunthorpe
2022-10-05 14:00 ` Christian Borntraeger [this message]
2022-10-05 14:01 ` Jason Gunthorpe
2022-10-05 14:19 ` Christian Borntraeger
2022-10-06 11:55 ` Christian Borntraeger
2022-10-05 14:21 ` Matthew Rosato
2022-10-05 15:40 ` Matthew Rosato
2022-10-05 14:01 ` Matthew Rosato
2022-10-04 19:59 ` Matthew Rosato
2022-10-04 20:19 ` Alex Williamson
2022-10-04 22:30 ` Jason Gunthorpe
2022-09-27 6:34 ` Yi Liu
2022-09-27 13:12 ` Jason Gunthorpe
2022-09-28 3:51 ` Tian, Kevin
2022-09-28 15:26 ` Jason Gunthorpe
2022-09-28 23:54 ` Tian, Kevin
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