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* kvm_log_clear_one_slot: Assertion `mem->dirty_bmap' failed
@ 2025-08-04 14:57 Pete Bridgman via
  2025-08-06 19:10 ` Peter Xu
  0 siblings, 1 reply; 2+ messages in thread
From: Pete Bridgman via @ 2025-08-04 14:57 UTC (permalink / raw)
  To: qemu-devel; +Cc: dgilbert, peterx, bonzini


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Good afternoon,

We're seeing a rare assertion failure in production on

    qemu-system-x86_64: ../../accel/kvm/kvm-all.c:909:
kvm_log_clear_one_slot: Assertion `mem->dirty_bmap' failed.

We have seen this very occasionally in logs from devices running QEMU 7.2
on Linux 5.19
with a Windows 10 guest, seemingly spontaneously; there are no migrations
involved which
afaict has been implicated when this assertion has been hit previously
(https://bugzilla.redhat.com/show_bug.cgi?id=1772774).

We would love to be able to reproduce this (ideally on a more recent QEMU
version) so that
we can determine whether a later QEMU version has resolved the issue, and
if not file a bug
/ work on a patch, but have thus far been unable to reproduce it on demand,
with only very
occasional logs from customer devices showing this issue.

Would anyone have any ideas about what conditions might make it more likely
to reproduce,
or any pointers on what might be going wrong here - or alternatively any
thoughts about
whether a later version might be expected to resolve this?

In the following bugzilla comment:
https://bugzilla.redhat.com/show_bug.cgi?id=1772774#c11
it was mentioned that perhaps this assertion failure could be downgraded to
an early exit as
it would likely be safe to continue operation in this case. Would anyone
have any thoughts on
this? Would we be unwise to make that change (even if in just our own fork?)

I have attached our QEMU command line for reference; many thanks in advance
for any insight
or guidance. I've CCd people who were involved in a bugfix for this
assertion failure previously
(9b3a31c7) on the advice of folks in IRC, hope you don't mind.

Kind regards

Pete

Peter Bridgman (he/him)

Co-Founder & CEO

+44 (0) 7917 448150
pb@fourieraudio.com
www.fourieraudio.com

Fourier Audio Ltd is registered in England and Wales (No. 13122782)
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/usr/bin/qemu-system-x86_64 \
-name guest=doppler-win-base,debug-threads=on \
-S \
-object '{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/var/lib/libvirt/qemu/domain-4-doppler-win-base/master-key.aes"}' \
-machine pc-q35-5.2,usb=off,vmport=off,dump-guest-core=off,memory-backend=pc.ram \
-accel kvm \
-cpu host,migratable=off,hv-time=on,kvmclock=off,kvm-pv-eoi=on,kvm-pv-unhalt=on,hv-relaxed=on,hv-vapic=on,hv-spinlocks=0x1fff,hv-vpindex=on,hv-runtime=on,hv-synic=on,hv-stimer=on,hv-stimer-direct=on,hv-frequencies=on,hv-tlbflush=on,hv-ipi=on,hv-avic=on,hv-crash,kvm-hint-dedicated=on,kvm-poll-control=on,host-cache-info=on,l3-cache=off \
-m 24576 \
-object '{"qom-type":"memory-backend-memfd","id":"pc.ram","hugetlb":true,"hugetlbsize":1073741824,"x-use-canonical-path-for-ramblock-id":false,"prealloc":true,"size":25769803776}' \
-overcommit mem-lock=on \
-smp 10,sockets=1,dies=1,cores=10,threads=1 \
-object '{"qom-type":"iothread","id":"iothread1"}' \
-object '{"qom-type":"iothread","id":"iothread2"}' \
-object '{"qom-type":"iothread","id":"iothread3"}' \
-object '{"qom-type":"iothread","id":"iothread4"}' \
-uuid b5cc201d-58cb-4e3b-b2e7-d540e2541e85 \
-smbios 'type=1,manufacturer=Fourier Audio,product=Doppler,version=0,serial=TF-RD-0,sku=FTE-0' \
-smbios 'type=2,manufacturer=Fourier Audio' \
-smbios 'type=3,manufacturer=Fourier Audio' \
-no-user-config \
-nodefaults \
-chardev socket,id=charmonitor,fd=33,server=on,wait=off \
-mon chardev=charmonitor,id=monitor,mode=control \
-rtc base=utc \
-no-hpet \
-global kvm-pit.lost_tick_policy=delay \
-no-shutdown \
-global ICH9-LPC.disable_s3=1 \
-global ICH9-LPC.disable_s4=1 \
-boot menu=off,strict=on \
-device '{"driver":"pcie-root-port","port":16,"chassis":1,"id":"pci.1","bus":"pcie.0","multifunction":true,"addr":"0x2"}' \
-device '{"driver":"pcie-root-port","port":17,"chassis":2,"id":"pci.2","bus":"pcie.0","addr":"0x2.0x1"}' \
-device '{"driver":"pcie-root-port","port":18,"chassis":3,"id":"pci.3","bus":"pcie.0","addr":"0x2.0x2"}' \
-device '{"driver":"pcie-root-port","port":19,"chassis":4,"id":"pci.4","bus":"pcie.0","addr":"0x2.0x3"}' \
-device '{"driver":"pcie-root-port","port":20,"chassis":5,"id":"pci.5","bus":"pcie.0","addr":"0x2.0x4"}' \
-device '{"driver":"pcie-root-port","port":21,"chassis":6,"id":"pci.6","bus":"pcie.0","addr":"0x2.0x5"}' \
-device '{"driver":"pcie-pci-bridge","id":"pci.7","bus":"pci.6","addr":"0x0"}' \
-device '{"driver":"qemu-xhci","p2":15,"p3":15,"id":"usb","bus":"pci.2","addr":"0x0"}' \
-device '{"driver":"virtio-serial-pci","id":"virtio-serial0","bus":"pci.3","addr":"0x0"}' \
-blockdev '{"driver":"file","filename":"/opt/fa/win/image/base.qcow2","node-name":"libvirt-4-storage","auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-4-format","read-only":true,"driver":"qcow2","file":"libvirt-4-storage","backing":null}' \
-blockdev '{"driver":"file","filename":"/var/opt/fa/image/current.qcow2","node-name":"libvirt-3-storage","auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-3-format","read-only":true,"driver":"qcow2","file":"libvirt-3-storage","backing":"libvirt-4-format"}' \
-blockdev '{"driver":"file","filename":"/var/opt/fa/image/user.qcow2","node-name":"libvirt-2-storage","auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-2-format","read-only":false,"driver":"qcow2","file":"libvirt-2-storage","backing":"libvirt-3-format"}' \
-device '{"driver":"ide-hd","bus":"ide.0","drive":"libvirt-2-format","id":"sata0-0-0","bootindex":1}' \
-blockdev '{"driver":"file","filename":"/opt/fa/winbin/winbin-current.qcow2","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-1-format","read-only":false,"driver":"qcow2","file":"libvirt-1-storage","backing":null}' \
-device '{"driver":"ide-hd","bus":"ide.1","drive":"libvirt-1-format","id":"sata0-0-1"}' \
-netdev '{"type":"tap","fd":"34","vhost":true,"vhostfd":"38","id":"hostnet0"}' \
-device '{"driver":"virtio-net-pci","netdev":"hostnet0","id":"net0","mac":"52:54:00:7a:e8:17","bus":"pci.1","addr":"0x0"}' \
-chardev pty,id=charserial0 \
-device '{"driver":"isa-serial","chardev":"charserial0","id":"serial0","index":0}' \
-device '{"driver":"usb-tablet","id":"input0","bus":"usb.0","port":"1"}' \
-audiodev '{"id":"audio1","driver":"none"}' \
-vnc 0.0.0.0:1,websocket=5902,password=on,audiodev=audio1 \
-device '{"driver":"qxl-vga","id":"video0","max_outputs":1,"ram_size":67108864,"vram_size":67108864,"vram64_size_mb":0,"vgamem_mb":16,"bus":"pcie.0","addr":"0x1"}' \
-device '{"driver":"virtio-balloon-pci","id":"balloon0","bus":"pci.4","addr":"0x0"}' \
-object '{"qom-type":"rng-random","id":"objrng0","filename":"/dev/random"}' \
-device '{"driver":"virtio-rng-pci","rng":"objrng0","id":"rng0","max-bytes":1024,"period":10,"bus":"pci.5","addr":"0x0"}' \
-device qemu-xhci,id=xhci-external,addr=0xF,p2=15,p3=15 \
-device usb-host,bus=xhci-external.0,hostbus=1,hostport=12,vendorid=0x088e,productid=0x5036 \
-device usb-host,bus=xhci-external.0,hostbus=1,hostport=10.1 \
-device usb-host,bus=xhci-external.0,hostbus=1,hostport=10.2 \
-device usb-host,bus=xhci-external.0,hostbus=1,hostport=10.3 \
-device usb-host,bus=xhci-external.0,hostbus=1,hostport=10.4 \
-device usb-host,bus=xhci-external.0,hostbus=1,hostport=3 \
-device usb-host,bus=xhci-external.0,hostbus=1,hostport=4 \
-device usb-host,bus=xhci-external.0,hostbus=2,hostport=3 \
-device usb-host,bus=xhci-external.0,hostbus=2,hostport=4 \
-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
-device '{"driver":"ivshmem-doorbell","id":"shmem0","chardev":"charshmem0","vectors":1,"ioeventfd":true,"bus":"pci.7","addr":"0x1"}' \
-chardev socket,id=charshmem0,path=/tmp/ivshmem_socket \
-msg timestamp=on

^ permalink raw reply	[flat|nested] 2+ messages in thread
end of thread, other threads:[~2025-08-06 19:11 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
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2025-08-04 14:57 kvm_log_clear_one_slot: Assertion `mem->dirty_bmap' failed Pete Bridgman via
2025-08-06 19:10 ` Peter Xu

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