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Subject: Re: [PATCH v1 1/1] KVM: add missing kvm_put_kvm in case of failure
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, borntraeger@de.ibm.com,
        frankja@linux.vnet.ibm.com
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 <66c8737e-20f7-627f-a1dd-8139d3304959@redhat.com>
 <20170627135007.GG10672@ZenIV.linux.org.uk>
From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <a3c75dcd-f31d-e8cc-3402-e43dbefe382d@redhat.com>
Date: Tue, 27 Jun 2017 15:57:23 +0200
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On 27/06/2017 15:50, Al Viro wrote:
>> Queued, thanks.
> It's broken.  Look: once we are past the anon_inode_getfile(), the
> reference we held on kvm is transferred into new struct file.  After
> that point we don't drop kvm - we drop file.  And as long as that
> file is held, it will keep holding what used to be our reference to
> kvm.  Once all references to file are gone, its ->release() will be
> called and that's where kvm reference in it will be dropped.
> 
> IOW, this patch introduces a double-put.

Yup, I've noticed your other reply (hopefully would have noticed during
regression testing).  Thanks Al.

Paolo