Hi Wei, On 27/06/18 14:26, Wei Xu wrote: > Sorry, I should highlight that I have only updated the default value > of CONFIG_NR_CPUS by menuconfig in the previous mail. > That is why it showed dirty.
(menuconfig changes don't show up like this) More than 64 CPUs ... Is this system running more VMs than it has VMIDs? Too-few VMIDs does work with KVM, its just going to trigger rollover frequently. Just to check, what kernel version is the host running? Does it have commit f0cf47d939d0 ("KVM: arm/arm64: Close VMID generation race") (looks like that went in as a fix for v4.17-rc3) Are you running (lots) of other VMs whenever this happens? Do they have multiple vcpus? (I'm thinking of the scenario in that patch's description) Is the host system otherwise idle when this happens? (If not, can you reproduce the issue without exhausting the VMIDs?) It may be that writing back the page-table entries with the MMU off, and changing the cache maintenance are just changing the timing of something else. Thanks, James