[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: Recent upgrade of 4.13 -> 4.14 issue
Hi list, This is a reply to the thread of the same title (linked here: https://www.mail-archive.com/xen-devel@xxxxxxxxxxxxxxxxxxxx/msg84916.html ) which I could not reply to because I receive this list by digest. I'm unclear if this is exactly the reason, but I experienced the same symptoms when upgrading to 4.14. The issue does not occur if I downgrade to 4.11 (the previous version that was provided by Debian). Kernel is 5.9.11 and unchanged between xen versions. One thing I noticed is that if I disable the monitor/mwait instructions on my CPU (Intel Xeon E5-2699 v4 ES), the stalls seem to occur later into the boot. With the instructions enabled, the system usually stalls less than a few minutes after boot; disabled, it can last for tens of minutes. Further disabling the HPET or forcing the kernel to use PIT causes it to be somewhat usable. The stalls still occur tens of minutes in but somehow everything seems to continue chugging along fine? I've also verified that the stalls do not occur in all the above cases if I just boot into the kernel without xen. When the stalls happen, I get the "rcu: INFO: rcu_sched detected stalls on CPUs/tasks" backtraces printed on the console periodically, but keystrokes don't do anything on the console, and I can't spawn new SSH sessions even though pinging the system produces a reply. The last item in the call trace is usually "xen_safe_halt", but I've seen it occur for other functions related to btrfs and the network adapter as well. Do let me know if there's anything I can provide to help troubleshoot this. At the moment I've reverted to 4.11, but I can temporarily switch over to 4.14 to collect any necessary information. Liwei
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