linux-kernel - Re: [PATCH] Drivers: hv: vmbus: hibernation: do not hang forever in vmbus_bus

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Message-ID: <20200909113758.7ucufasongrttxdw@liuwe-devbox-debian-v2>
Date:   Wed, 9 Sep 2020 11:37:58 +0000
From:   Wei Liu <wei.liu@...nel.org>
To:     Michael Kelley <mikelley@...rosoft.com>
Cc:     Dexuan Cui <decui@...rosoft.com>,
        "wei.liu@...nel.org" <wei.liu@...nel.org>,
        KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        vkuznets <vkuznets@...hat.com>
Subject: Re: [PATCH] Drivers: hv: vmbus: hibernation: do not hang forever in
 vmbus_bus_resume()

On Tue, Sep 08, 2020 at 09:05:34PM +0000, Michael Kelley wrote:
> From: Dexuan Cui <decui@...rosoft.com> Sent: Friday, September 4, 2020 7:56 PM
> > 
> > After we Stop and later Start a VM that uses Accelerated Networking (NIC
> > SR-IOV), currently the VF vmbus device's Instance GUID can change, so after
> > vmbus_bus_resume() -> vmbus_request_offers(), vmbus_onoffer() can not find
> > the original vmbus channel of the VF, and hence we can't complete()
> > vmbus_connection.ready_for_resume_event in check_ready_for_resume_event(),
> > and the VM hangs in vmbus_bus_resume() forever.
> > 
> > Fix the issue by adding a timeout, so the resuming can still succeed, and
> > the saved state is not lost, and according to my test, the user can disable
> > Accelerated Networking and then will be able to SSH into the VM for
> > further recovery. Also prevent the VM in question from suspending again.
> > 
> > The host will be fixed so in future the Instance GUID will stay the same
> > across hibernation.
> > 
> > Fixes: d8bd2d442bb2 ("Drivers: hv: vmbus: Resume after fixing up old primary channels")
> > Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> > ---
> >  drivers/hv/vmbus_drv.c | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> Reviewed-by: Michael Kelley <mikelley@...rosoft.com>
> 

Applied to hyperv-fixes. Thanks.