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
