On Thu, Nov 08, 2018 at 07:10:58PM +0800, Ming Lei wrote: > I guess the issue may depend on specific QEMU version, just tried the test over > virtio-scsi/sata/usb-storage emulated via qemu-2.10.2-1.fc27, not observed > this problem. I actually didn't use virtio-scsi, but it really doesn't matter. FWIW, this is what I ran: # qemu-system-x86_64 --version QEMU emulator version 2.10.2(qemu-2.10.2-1.fc27) # qemu-system-x86_64 -m 192 -smp 2 -enable-kvm -display none -snapshot \ -hda /mnt/images/fedora-27.img -nographic \ -append "console=tty0 console=ttyS0 root=/dav/sda rw" \ -kernel /boot/vmlinuz-4.18.10-100.fc27.x86_64 \ -initrd /boot/initramfs-4.18.10-100.fc27.x86_64.img The file "fedora-27.img" is just a filesystem image of a minimal mock setup from /var/lib/mock/fedora-27-x86_64/root/. A small memory size makes it easier to observe, otherwise your probability of allocating unclean pages lowers. That's really the only reason I used qemu since all my real machines have too much memory that I never come close to using, making observations more random.