Re: [PATCH v2 0/4] qemu: Add support for free-page-reporting

On 10/14/20 2:06 PM, David Hildenbrand wrote: > On 14.10.20 13:53, Michal Privoznik wrote: >> On 10/14/20 10:26 AM, David Hildenbrand wrote: >>> On 14.10.20 08:30, Michal Privoznik wrote: >> > <snip/> > > No, not at all. Thanks for reporting! > > And the "bad" thing is, that QEMU doesn't do anything too fancy. All it > does is "fallocate(FALLOC_FL_PUNCH_HOLE)" on hugetlbfs when trying to > zap reported pages. The same mechanism is also used for postcopy live > migration and virtio-mem with hugetlbfs. > > Which kernel are you running? > > 1. Is it an upstream kernel, lkml + -mm lists are the right place > (please cc me, or I can try to reproduce and report it). > > 2. Is it a distro kernel? Then create a BUG there. > > I was just recently testing virtio-mem with hugetlbfs and it worked on > decent upstream Fedora. But maybe I was not able to trigger it. Okay, I've upgraded to 5.9.0-gentoo, but the problem persists. Gentoo puts only a very few patches on top of vanilla kernel neither of which touches that area of the code: https://dev.gentoo.org/~mpagano/genpatches/trunk/5.9/ So I think this is reproducible on vanilla too. BTW: Have you tried placing the qemu inside v1 cgroups? Libvirt does that so maybe that's the problem. Anyway, here's the cmd line: /home/zippy/work/qemu/qemu.git/build/qemu-system-x86_64 \ -name guest=fedora,debug-threads=on \ -S \ -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-2-fedora/master-key.aes \ -machine pc-i440fx-4.0,accel=kvm,usb=off,dump-guest-core=off,memory-backend=pc.ram \ -cpu host,migratable=on \ -m 4096 \ -object memory-backend-memfd,id=pc.ram,hugetlb=yes,hugetlbsize=2097152,prealloc=yes,size=4294967296,host-nodes=0,policy=bind \ -overcommit mem-lock=off \ -smp 4,sockets=1,dies=1,cores=2,threads=2 \ -object iothread,id=iothread1 \ -object iothread,id=iothread2 \ -object iothread,id=iothread3 \ -object iothread,id=iothread4 \ -uuid 63840878-0deb-4095-97e6-fc444d9bc9fa \ -no-user-config \ -nodefaults \ -device sga \ -chardev socket,id=charmonitor,fd=33,server,nowait \ -mon chardev=charmonitor,id=monitor,mode=control \ -rtc base=utc \ -no-shutdown \ -global PIIX4_PM.disable_s3=0 \ -global PIIX4_PM.disable_s4=0 \ -boot menu=on,strict=on \ -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 \ -device virtio-scsi-pci,id=scsi0,bus=pci.0,addr=0x4 \ -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5 \ -blockdev '{"driver":"file","filename":"/var/lib/libvirt/images/fedora.qcow2","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \ -blockdev '{"node-name":"libvirt-1-format","read-only":false,"discard":"unmap","driver":"qcow2","file":"libvirt-1-storage","backing":null}' \ -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,device_id=drive-scsi0-0-0-0,drive=libvirt-1-format,id=scsi0-0-0-0,bootindex=1 \ -netdev tap,fd=35,id=hostnet0 \ -device virtio-net-pci,host_mtu=9000,netdev=hostnet0,id=net0,mac=52:54:00:a4:6f:91,bus=pci.0,addr=0x3 \ -chardev pty,id=charserial0 \ -device isa-serial,chardev=charserial0,id=serial0 \ -chardev socket,id=charchannel0,fd=36,server,nowait \ -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0 \ -spice port=5900,addr=127.0.0.1,disable-ticketing,seamless-migration=on \ -device virtio-vga,id=video0,virgl=on,max_outputs=1,bus=pci.0,addr=0x2 \ -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x7,free-page-reporting=on \ -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \ -msg timestamp=on

Michal