(Re-CC'ing people from the old thread) On Fri, Feb 10, 2023 at 4:57 AM Dexuan Cui <decui@xxxxxxxxxxxxx> wrote: > > > From: Mohammed Gamal <mgamal@xxxxxxxxxx> > > Sent: Thursday, February 9, 2023 1:48 AM > > ... > > > We saw this when triggering a crash with kdump enabled with > > > echo 'c' > /proc/sysrq-trigger > > > > > > When the new kernel boots, we see this stack trace: > > Thanks for the details. Kdump is special in that the 'old' VMBus > channels might still be active (from the host's perspective), > when the new kernel starts to run. > > Upon crash, Linux sends a CHANNELMSG_UNLOAD messge to the host, > and the host is supposed to quiesce/reset the VMBus devices, so > normally we should not see a crash in relid2channel(). Does this not happen in the case of kdump? Shouldn't a CHANNELMSG_UNLOAD message be sent to the host in that case as well? > > > > [ 21.906679] Hardware name: Microsoft Corporation Virtual > > > Machine/Virtual Machine, BIOS 090007 05/18/2018 > > I guess you see the crash because you're running an old Hyper-V, > probably Windows Server 2016 or 2019, which may be unable to > reliably handle the guest's CHANNELMSG_UNLOAD messge. We've actually seen this on Windows Server 2016, 2019, and 2022. > > Can you please mention kdump in the commit message? > Will do. > BTW, regarding "before vmbus_connect() is called ", IMO it > should be "before vmbus_connect() is called or before it finishes".
