We have been having some stability issues on the machine that serves private virtual servers vps1-vps8 since kernel 5.8 where there were some major changes that significantly improved load and responsiveness and hence the unwillingness to revert to 5.4.  I have filed a bug report on various issues that have shown up in crash dumps with the kernel Bugzilla but so far they have not directly addressed them.

     This morning, this server spontaneously rebooted, it did not print a crash dump, only a watchdog timer timeout.  But since last Friday the kernel team has kicked out a new release that addresses an issue with memory allocation that under certain circumstances could cause already allocated memory to be re-allocated and they’ve made many fixes to KVM code which is the hypervisor we are using to serve private virtual servers so could be relevant.

     I am going to do a kernel upgrade on just this server at 11PM tonight.  This will cause a brief interruption of all virtual private servers lasting 5-10 minutes.  Since no NFS/NIS mounts are involved, I do not expect it to take as long as normal updates do.