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Bug 1354090 - Boot guest with vhostuser server mode, QEMU prompt 'Segmentation fault' after executing '(qemu)system_powerdown'
Summary: Boot guest with vhostuser server mode, QEMU prompt 'Segmentation fault' after...
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: qemu-kvm-rhev
Version: 7.3
Hardware: x86_64
OS: Linux
Target Milestone: rc
: ---
Assignee: Marc-Andre Lureau
QA Contact: Pei Zhang
: 1355659 (view as bug list)
Depends On:
Blocks: 1356892
TreeView+ depends on / blocked
Reported: 2016-07-09 12:13 UTC by Pei Zhang
Modified: 2016-11-07 21:22 UTC (History)
11 users (show)

Fixed In Version: qemu-kvm-rhev-2.6.0-15.el7
Doc Type: Bug Fix
Doc Text:
When a guest virtual machine was configured as a vhost-user server and the back end was restarted, the guest was not able to recover. With this update, the back end is able to discard the SET_VRING_BASE value and resume from index. This allows the guest to recover successfully in the described scenario.
Clone Of:
: 1356892 (view as bug list)
Last Closed: 2016-11-07 21:22:24 UTC
Target Upstream Version:

Attachments (Terms of Use)

System ID Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2016:2673 normal SHIPPED_LIVE qemu-kvm-rhev bug fix and enhancement update 2016-11-08 01:06:13 UTC

Description Pei Zhang 2016-07-09 12:13:07 UTC
Description of problem:
Boot guest with vhostuser server mode, QEMU prompt 'Segmentation fault' after executing '(qemu)system_powerdown'. 

Version-Release number of selected component (if applicable):


How reproducible:

Steps to Reproduce:
1. Run a slirp/vlan in a background process
# /usr/libexec/qemu-kvm \
-net none \
-net socket,vlan=0,udp=localhost:4444,localaddr=localhost:5555 \
-net user,vlan=0

2. Start qemu with vhost-user as server mode
# /usr/libexec/qemu-kvm  -m 1024 -smp 2 \
-object memory-backend-file,id=mem,size=1024M,mem-path=/dev/hugepages,share=on \
-numa node,memdev=mem -mem-prealloc \
-chardev socket,id=char0,path=/tmp/vubr.sock,server \
-netdev type=vhost-user,id=mynet1,chardev=char0,vhostforce \
-device virtio-net-pci,netdev=mynet1,mac=54:52:00:1a:2c:01 \
/home/pezhang/rhel7.3.qcow2 \
-monitor stdio \
-vga std -vnc :10 \

QEMU waiting for connection on: disconnected:unix:/tmp/vubr.sock,server

3. Start vubr as vhostuser client
# ./vhost-user-bridge -c

4. After guest boot up, shutdown it. Qemu will prompt error info.
(qemu) system_powerdown 
(qemu) Segmentation fault

Actual results:
Qemu doesn't quit well.

Expected results:
Qemu should quit correctly without any error info.

Additional info:
1. gdb info
(qemu) system_powerdown 
Program received signal SIGSEGV, Segmentation fault.
0x00005555558f3128 in object_class_dynamic_cast (class=class@entry=0x55555945ee80, 
    typename=typename@entry=0x5555559c33f9 "qio-channel") at qom/object.c:662
662	    if (type->class->interfaces &&
(gdb) bt
#0  0x00005555558f3128 in object_class_dynamic_cast (class=class@entry=0x55555945ee80, 
    typename=typename@entry=0x5555559c33f9 "qio-channel") at qom/object.c:662
#1  0x00005555558f32b5 in object_class_dynamic_cast_assert (class=0x55555945ee80, 
    typename=typename@entry=0x5555559c33f9 "qio-channel", file=file@entry=0x555555a3f366 "io/channel.c", line=line@entry=60, 
    func=func@entry=0x555555a3f500 <__func__.20656> "qio_channel_writev_full") at qom/object.c:712
#2  0x000055555595b817 in qio_channel_writev_full (ioc=0x55555945ef80, iov=0x7fffffff9890, niov=1, fds=0x0, nfds=0, errp=0x0)
    at io/channel.c:60
#3  0x00005555557c6974 in io_channel_send_full (ioc=0x55555945ef80, buf=0x7fffffff99a0, len=20, fds=0x0, nfds=0)
    at qemu-char.c:966
#4  0x00005555557c6a33 in tcp_chr_write (chr=<optimized out>, buf=<optimized out>, len=<optimized out>) at qemu-char.c:2658
#5  0x00005555557c76eb in qemu_chr_fe_write_buffer (s=s@entry=0x555556c03c20, buf=buf@entry=0x7fffffff99a0 "\v", len=20, 
    offset=offset@entry=0x7fffffff9950) at qemu-char.c:250
#6  0x00005555557ca073 in qemu_chr_fe_write_all (s=s@entry=0x555556c03c20, buf=buf@entry=0x7fffffff99a0 "\v", 
    len=len@entry=20) at qemu-char.c:310
#7  0x0000555555749f1f in vhost_user_write (msg=msg@entry=0x7fffffff99a0, fds=fds@entry=0x0, fd_num=fd_num@entry=0, 
    dev=0x555556b3dc00, dev=0x555556b3dc00) at /usr/src/debug/qemu-2.6.0/hw/virtio/vhost-user.c:195
#8  0x000055555574aa2c in vhost_user_get_vring_base (dev=0x555556b3dc00, ring=0x7fffffff9ae0)
    at /usr/src/debug/qemu-2.6.0/hw/virtio/vhost-user.c:364
#9  0x00005555557481b0 in vhost_virtqueue_stop (dev=dev@entry=0x555556b3dc00, vdev=vdev@entry=0x555559c14328, 
    vq=0x555556b3dd38, idx=0) at /usr/src/debug/qemu-2.6.0/hw/virtio/vhost.c:924
#10 0x00005555557497c4 in vhost_dev_stop (hdev=hdev@entry=0x555556b3dc00, vdev=vdev@entry=0x555559c14328)
    at /usr/src/debug/qemu-2.6.0/hw/virtio/vhost.c:1290
#11 0x0000555555735c28 in vhost_net_stop_one (net=0x555556b3dc00, dev=dev@entry=0x555559c14328)
    at /usr/src/debug/qemu-2.6.0/hw/net/vhost_net.c:288
#12 0x000055555573610b in vhost_net_stop (dev=dev@entry=0x555559c14328, ncs=<optimized out>, 
    total_queues=total_queues@entry=1) at /usr/src/debug/qemu-2.6.0/hw/net/vhost_net.c:367
#13 0x0000555555733455 in virtio_net_vhost_status (status=7 '\a', n=0x555559c14328)
    at /usr/src/debug/qemu-2.6.0/hw/net/virtio-net.c:158
#14 virtio_net_set_status (vdev=<optimized out>, status=<optimized out>) at /usr/src/debug/qemu-2.6.0/hw/net/virtio-net.c:224
---Type <return> to continue, or q <return> to quit---
#15 0x00005555558b720f in qmp_set_link (name=name@entry=0x555556b30bd0 "mynet1", up=up@entry=false, 
    errp=errp@entry=0x7fffffffbc68) at net/net.c:1368
#16 0x00005555558bd7ef in net_vhost_user_event (opaque=0x555556b30bd0, event=5) at net/vhost-user.c:226
#17 0x00005555557cc132 in qemu_chr_free (chr=0x555556c03c20) at qemu-char.c:4037
#18 0x00005555557cce7f in qemu_chr_cleanup () at qemu-char.c:4574
#19 0x00005555556c7611 in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at vl.c:4676

2. This bug was caused by patches of Bug 1347077.

Comment 3 Ademar Reis 2016-07-12 16:10:56 UTC
*** Bug 1355659 has been marked as a duplicate of this bug. ***

Comment 4 Marc-Andre Lureau 2016-07-14 20:59:54 UTC
patches are now merged upstream, backport has been sent to rhvirt for review,  brew builds:



Comment 6 Miroslav Rezanina 2016-07-20 08:50:57 UTC
Fix included in qemu-kvm-rhev-2.3.0-31.el7_2.19

Comment 8 Miroslav Rezanina 2016-07-22 09:12:05 UTC
Fix included in qemu-kvm-rhev-2.6.0-15.el7

Comment 10 Pei Zhang 2016-07-22 09:59:48 UTC

1. Run a slirp/vlan in a background process
2. Start qemu with vhost-user as server mode
3. Start vubr as vhostuser client
(Step1~3 have same commands and results as Description)

4. After guest boot up, shutdown it. Qemu quit well.
(qemu) system_powerdown 
in guest:
# shutdown -h now

So this bug has been fixed well. Thank you.

Comment 12 errata-xmlrpc 2016-11-07 21:22:24 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

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