On 14.05.20 13:10, David Hildenbrand wrote: > On 14.05.20 12:12, David Hildenbrand wrote: >> On 14.05.20 12:02, teawater wrote: >>> >>> >>>> 2020年5月14日 16:48,David Hildenbrand <david@xxxxxxxxxx> 写道: >>>> >>>> On 14.05.20 08:44, teawater wrote: >>>>> Hi David, >>>>> >>>>> I got a kernel warning with v2 and v3. >>>> >>>> Hi Hui, >>>> >>>> thanks for playing with the latest versions. Surprisingly, I can >>>> reproduce even by hotplugging a DIMM instead as well - that's good, so >>>> it's not related to virtio-mem, lol. Seems to be some QEMU setup issue >>>> with older machine types. >>>> >>>> Can you switch to a newer qemu machine version, especially >>>> pc-i440fx-5.0? Both, hotplugging DIMMs and virtio-mem works for me with >>>> that QEMU machine just fine. >>> >>> I still could reproduce this issue with pc-i440fx-5.0 or pc. Did I miss anything? >>> >> >> Below I don't even see virtio_mem. I had to repair the image (filesystem >> fsck) because it was broken, can you try that as well? >> >> Also, it would be great if you could test with v4. >> > > Correction, something seems to be broken either in QEMU or the kernel. Once I > define a DIMM so it's added and online during boot, I get these issues: > > (I have virtio-mem v4 installed in the guest) > > #! /bin/bash > sudo x86_64-softmmu/qemu-system-x86_64 \ > -machine pc-i440fx-5.0,accel=kvm,usb=off \ > -cpu host \ > -no-reboot \ > -nographic \ > -device ide-hd,drive=hd \ > -drive if=none,id=hd,file=/home/dhildenb/git/Fedora-Cloud-Base-31-1.9.x86_64.qcow2,format=qcow2 \ > -m 1g,slots=10,maxmem=2G \ > -smp 1 \ > -object memory-backend-ram,id=mem0,size=256m \ > -device pc-dimm,id=dimm0,memdev=mem0 \ > -s \ > -monitor unix:/var/tmp/monitor,server,nowait > > > Without the DIMM it seems to work just fine. > And another correction. Using QEMU v5.0.0, Linux 5.7-rc5, untouched Fedora-Cloud-Base-32-1.6.x86_64.qcow2, I get even without any memory hotplug: #! /bin/bash sudo x86_64-softmmu/qemu-system-x86_64 \ -machine pc-i440fx-5.0,accel=kvm,usb=off \ -cpu host \ -no-reboot \ -nographic \ -device ide-hd,drive=hd \ -drive if=none,id=hd,file=/home/dhildenb/git/Fedora-Cloud-Base-32-1.6.x86_64.qcow2,format=qcow2 \ -m 5g,slots=10,maxmem=6G \ -smp 1 \ -s \ -kernel /home/dhildenb/git/linux/arch/x86/boot/bzImage \ -append "console=ttyS0 rd.shell nokaslr swiotlb=noforce" \ -monitor unix:/var/tmp/monitor,server,nowait Observe how big the initial RAM even is! So this is no DIMM/hotplug/virtio_mem issue. With memory hotplug, it seems to get more likely to trigger if "swiotlb=noforce" is not specified. "swiotlb=noforce" seems to trigger some pre-existing issue here. Without "swiotlb=noforce", I was only able to observe this via pc-i440fx-2.1, -- Thanks, David / dhildenb