Re: [Qemu-devel] qemu 2.0, deadlock in block-commit

["Marcin Gibuła" <m.gibula@beyond.pl>]

W dniu 2014-05-22 22:49, Marcin Gibuła pisze:
>
> Thread 1 (Thread 0x7f699bfcd900 (LWP 13647)):
> #0  0x00007f6998020286 in ppoll () from /lib64/libc.so.6
> #1  0x00007f699c1f3d9b in ppoll (__ss=0x0, __timeout=0x0,
> __nfds=<optimized out>, __fds=<optimized out>) at
> /usr/include/bits/poll2.h:77
> #2  qemu_poll_ns (fds=<optimized out>, nfds=<optimized out>,
> timeout=<optimized out>) at
> /var/tmp/portage/app-emulation/qemu-2.0.0_rc2/work/qemu-2.0.0-rc2/qemu-timer.c:311
> #3  0x00007f699c0877e0 in aio_poll (ctx=0x7f699e4c9c00,
> blocking=blocking@entry=true) at
> /var/tmp/portage/app-emulation/qemu-2.0.0_rc2/work/qemu-2.0.0-rc2/aio-posix.c:221
> #4  0x00007f699c095c0a in bdrv_drain_all () at
> /var/tmp/portage/app-emulation/qemu-2.0.0_rc2/work/qemu-2.0.0-rc2/block.c:1805

Some more info.
VM was doing lot of write IO during this test.

ppoll() is listening for these descriptors (from strace):

ppoll([{fd=25, events=POLLIN|POLLERR|POLLHUP}, {fd=23, 
events=POLLIN|POLLERR|POLLHUP}, {fd=17, events=POLLIN|POLLERR|POLLHUP}, 
{fd=4, events=POLLIN|POLLERR|POLLHUP}], 4, NULL, NULL, 8, ...)

fd # ls -l 25 23 17 4
lrwx------ 1 usr_5062 qemu 64 May 22 23:00 17 -> anon_inode:[eventfd]
lrwx------ 1 usr_5062 qemu 64 May 22 23:00 23 -> anon_inode:[eventfd]
lrwx------ 1 usr_5062 qemu 64 May 22 23:00 25 -> anon_inode:[eventfd]
lrwx------ 1 usr_5062 qemu 64 May 22 23:00 4 -> anon_inode:[eventfd]

VM is started via libvirt. No errors are reported in logs.
Command line is:

/usr/bin/qemu-system-x86_64 -machine accel=kvm -name 
68189c3c-02f6-4aae-88a2-5f13c5e6f53a -S -machine 
pc-i440fx-2.0,accel=kvm,usb=off -cpu SandyBridge,-kvmclock -m 1536 
-realtime mlock=on -smp 2,sockets=2,cores=10,threads=1 -uuid 
68189c3c-02f6-4aae-88a2-5f13c5e6f53a -smbios type=0,vendor=HAL 9000 
-smbios type=1,manufacturer=cloud -no-user-config -nodefaults -chardev 
socket,id=charmonitor,path=/var/lib/libvirt/qemu/68189c3c-02f6-4aae-88a2-5f13c5e6f53a.monitor,server,nowait 
-mon chardev=charmonitor,id=monitor,mode=control -rtc 
base=utc,clock=vm,driftfix=slew -global kvm-pit.lost_tick_policy=discard 
-no-shutdown -boot menu=off,strict=on -device 
piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device 
virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5 -drive 
file=/dev/cube2/5f751718-ff36-420f-b034-5f31230b5f23,if=none,id=drive-virtio-disk0,format=raw,cache=none,aio=native,bps_rd=57671680,bps_wr=57671680,iops_rd=275,iops_wr=275 
-device 
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x6,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=2 
-drive 
file=/dev/cube1/c5b7a6e3-11f8-4b08-ac3e-5ea054028221,if=none,id=drive-virtio-disk1,format=raw,cache=none,aio=native,bps_rd=57671680,bps_wr=57671680,iops_rd=275,iops_wr=275 
-device 
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x7,drive=drive-virtio-disk1,id=virtio-disk1 
-drive 
file=/mnt/nfs/volumes/66346c1b-add5-4412-89d9-b00a3bb13e75/72be1b50-982e-458a-9a84-c0fbd48b4b3c.qcow2,if=none,id=drive-virtio-disk2,format=qcow2,cache=none,aio=threads,bps_rd=57671680,bps_wr=57671680,iops_rd=275,iops_wr=275 
-device 
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x8,drive=drive-virtio-disk2,id=virtio-disk2 
-drive 
file=/mnt/nfs/volumes/a20c3b29-6f21-4b3d-a3fb-8b80599e50df/b84716ea-2564-47cc-bbbf-dea6029132b4.qcow2,if=none,id=drive-virtio-disk3,format=qcow2,cache=none,aio=threads,bps_rd=57671680,bps_wr=57671680,iops_rd=275,iops_wr=275 
-device 
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x9,drive=drive-virtio-disk3,id=virtio-disk3 
-drive 
file=/mnt/nfs/volumes/0c2996b5-abec-47ea-9e88-ebd7ebf0c79d/453cb20a-1705-45e2-9f9e-bc1ea096d52a.qcow2,if=none,id=drive-virtio-disk4,format=qcow2,cache=none,aio=threads,bps_rd=57671680,bps_wr=57671680,iops_rd=275,iops_wr=275 
-device 
virtio-blk-pci,scsi=off,bus=pci.0,addr=0xa,drive=drive-virtio-disk4,id=virtio-disk4 
-drive 
file=/mnt/nfs/volumes/7dcbd9ba-f0bc-4d3c-9b5c-b2ac824584d5/a8bb7e11-a9b5-4613-9b63-b9722fba2166.qcow2,if=none,id=drive-virtio-disk5,format=qcow2,cache=none,aio=threads,bps_rd=57671680,bps_wr=57671680,iops_rd=275,iops_wr=275 
-device 
virtio-blk-pci,scsi=off,bus=pci.0,addr=0xb,drive=drive-virtio-disk5,id=virtio-disk5 
-drive 
file=rbd:iso-images/rescue.iso:auth_supported=none,if=none,id=drive-ide0-0-0,readonly=on,format=raw 
-device 
ide-cd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1 
-netdev tap,fd=19,id=hostnet0,vhost=on,vhostfd=20 -device 
virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:82:41:c9,bus=pci.0,addr=0x3 
-netdev tap,fd=21,id=hostnet1,vhost=on,vhostfd=22 -device 
virtio-net-pci,netdev=hostnet1,id=net1,mac=52:54:00:70:10:35,bus=pci.0,addr=0x4 
-chardev pty,id=charserial0 -device 
isa-serial,chardev=charserial0,id=serial0 -chardev 
socket,id=charchannel0,path=/var/lib/libvirt/qemu/68189c3c-02f6-4aae-88a2-5f13c5e6f53a.agent,server,nowait 
-device 
virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0 
-chardev 
socket,id=charchannel1,path=/var/lib/libvirt/qemu/68189c3c-02f6-4aae-88a2-5f13c5e6f53a.cloud.agent,server,nowait 
-device 
virtserialport,bus=virtio-serial0.0,nr=2,chardev=charchannel1,id=channel1,name=com.cloud.guest_agent.1 
-device usb-tablet,id=input0 -vnc 0.0.0.0:0,password -device 
cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device 
virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0xc -sandbox on -device 
pvpanic

-- 
mg