sigfault in virObjectLockGuard
Claudio Fontana
cfontana at suse.de
Thu Mar 17 12:28:20 UTC 2022
Hello all,
while experimenting with upstream libvirt, I encountered the following segfault when trying to virt-install a centos7 guest:
----
#! /bin/bash
ISO=CentOS-7-x86_64-Minimal-2009.iso
DISK=centos7.qcow2
rm ${DISK}
qemu-img create -f qcow2 ${DISK} 30G
virt-install --virt-type=kvm --name=centos7 --vcpus=2 --memory=30720 --location ${ISO} --disk path=${DISK},format=qcow2 --network default --graphics none --os-variant=centos7.0 --extra-args console=ttyS0
-----
This triggers a segfault in libvirtd as follows:
Thread 5 "rpc-libvirtd" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fca0b7fe640 (LWP 55658)]
___pthread_mutex_lock (mutex=mutex at entry=0x18) at pthread_mutex_lock.c:80
80 unsigned int type = PTHREAD_MUTEX_TYPE_ELISION (mutex);
(gdb) bt
#0 ___pthread_mutex_lock (mutex=mutex at entry=0x18) at pthread_mutex_lock.c:80
#1 0x00007fca132b8275 in virMutexLock (m=m at entry=0x18) at ../src/util/virthread.c:91
#2 0x00007fca132b829a in virLockGuardLock (m=0x18) at ../src/util/virthread.c:102
#3 0x00007fca1329c519 in virObjectLockGuard (anyobj=anyobj at entry=0x7fca13539310 <virNetDevGenNames+16>) at ../src/util/virobject.c:441
#4 0x00007fca1328b5f1 in virNetDevGenerateName (ifname=ifname at entry=0x7fca00018158, type=type at entry=VIR_NET_DEV_GEN_NAME_VNET)
at ../src/util/virnetdev.c:3619
#5 0x00007fca13293b9d in virNetDevTapCreate
(ifname=ifname at entry=0x7fca00018158, tunpath=tunpath at entry=0x7fca0845accd "/dev/net/tun", tapfd=tapfd at entry=0x7fca00043fc0, tapfdSize=tapfdSize at entry=1, flags=flags at entry=3) at ../src/util/virnetdevtap.c:183
#6 0x00007fca13294501 in virNetDevTapCreateInBridgePort
(brname=brname at entry=0x7fca000163c0 "br0", ifname=ifname at entry=0x7fca00018158, macaddr=macaddr at entry=0x7fca00018034, vmuuid=vmuuid at entry=0x7fca000156b8 "\232T\020\250~\024Mn\211\227\062\"\264\001\025\030", tunpath=tunpath at entry=0x7fca0845accd "/dev/net/tun", tapfd=tapfd at entry=0x7fca00043fc0, tapfdSize=1, virtPortProfile=0x0, virtVlan=0x0, isolatedPort=VIR_TRISTATE_BOOL_ABSENT, coalesce=0x0, mtu=0, actualMTU=0x0, flags=3) at ../src/util/virnetdevtap.c:602
#7 0x00007fca083d66f5 in qemuInterfaceBridgeConnect
(def=def at entry=0x7fca000156b0, driver=driver at entry=0x7fc9c0050980, net=net at entry=0x7fca00018030, tapfd=tapfd at entry=0x7fca00043fc0, tapfdSize=tapfdSize at entry=0x7fca0b7fd410) at ../src/qemu/qemu_interface.c:564
#8 0x00007fca08370f35 in qemuBuildInterfaceCommandLine
(vm=<optimized out>, vm=<optimized out>, nicindexes=0x7fca0b7fd570, nnicindexes=0x7fca0b7fd568, standalone=false, vmop=VIR_NETDEV_VPORT_PROFILE_OP_CREATE, qemuCaps=0x7fc9fc0145a0 [virQEMUCaps], net=0x7fca00018030, cmd=0x7fca00041300, driver=0x7fc9c0050980)
at ../src/qemu/qemu_command.c:8669
#9 qemuBuildNetCommandLine
(nicindexes=0x7fca0b7fd570, nnicindexes=0x7fca0b7fd568, standalone=<optimized out>, vmop=VIR_NETDEV_VPORT_PROFILE_OP_CREATE, qemuCaps=0x7fc9fc0145a0 [virQEMUCaps], cmd=0x7fca00041300, vm=<optimized out>, driver=0x7fc9c0050980) at ../src/qemu/qemu_command.c:8958
#10 qemuBuildCommandLine (driver=driver at entry=0x7fc9c0050980, vm=0x7fc9fc31f5e0 [virDomainObj],
vm at entry=0x2200000000, migrateURI=0x0, snapshot=0x0,
snapshot at entry=0x7fc9c0013190, vmop=vmop at entry=VIR_NETDEV_VPORT_PROFILE_OP_CREATE, standalone=standalone at entry=false, enableFips=false, nnicindexes=0x7fca0b7fd568, nicindexes=0x7fca0b7fd570, flags=0) at ../src/qemu/qemu_command.c:10548
#11 0x00007fca0841adc2 in qemuProcessLaunch
(conn=0x7fc9c0022070, driver=0x7fc9c0050980, vm=0x2200000000, asyncJob=QEMU_ASYNC_JOB_NONE, incoming=0x0, snapshot=0x7fc9c0013190, vmop=VIR_NETDEV_VPORT_PROFILE_OP_CREATE, flags=17) at ../src/qemu/qemu_process.c:7435
#12 0x00007fca08420669 in qemuProcessStart
(conn=conn at entry=0x7fc9c0013190, driver=driver at entry=0x7fc9c0050980, vm=0x7fc9fc31f5e0 [virDomainObj], updatedCPU=updatedCPU at entry=0x0, asyncJob=asyncJob at entry=QEMU_ASYNC_JOB_START, migrateFrom=migrateFrom at entry=0x0, migrateFd=-1, migratePath=0x0, snapshot=0x0, vmop=VIR_NETDE--Type <RET> for more, q to quit, c to continue without paging--
V_VPORT_PROFILE_OP_CREATE, flags=<optimized out>) at ../src/qemu/qemu_process.c:7855
#13 0x00007fca083b3e10 in qemuDomainCreateXML (conn=0x7fc9c0013190, xml=<optimized out>, flags=0) at ../src/qemu/qemu_driver.c:1628
#14 0x00007fca133e46f0 in virDomainCreateXML
(conn=0x7fc9c0013190, xmlDesc=0x7fca00008760 "<domain type=\"kvm\">\n <name>centos7</name>\n <uuid>9a5410a8-7e14-4d6e-8997-3222b4011518</uuid>\n <metadata>\n <libosinfo:libosinfo xmlns:libosinfo=\"http://libosinfo.org/xmlns/libvirt/domain/1.0\">\n "..., flags=0)
at ../src/libvirt-domain.c:180
#15 0x0000564bb33d631f in remoteDispatchDomainCreateXML
(server=0x564bb3dd1880 [virNetServer], msg=0x564bb3e81620, ret=0x7fca0000bfa0, args=0x7fca00002510, rerr=0x7fca0b7fd9a0, client=0x564bb3e80030 [virNetServerClient]) at src/remote/remote_daemon_dispatch_stubs.h:5083
#16 remoteDispatchDomainCreateXMLHelper
(server=0x564bb3dd1880 [virNetServer], client=0x564bb3e80030 [virNetServerClient], msg=0x564bb3e81620, rerr=0x7fca0b7fd9a0, args=0x7fca00002510, ret=0x7fca0000bfa0) at src/remote/remote_daemon_dispatch_stubs.h:5064
#17 0x00007fca13374426 in virNetServerProgramDispatchCall
(msg=0x564bb3e81620, client=0x564bb3e80030 [virNetServerClient], server=0x564bb3dd1880 [virNetServer], prog=0x564bb3e3c010 [virNetServerProgram]) at ../src/rpc/virnetserverprogram.c:428
#18 virNetServerProgramDispatch
(prog=0x564bb3e3c010 [virNetServerProgram], server=server at entry=0x564bb3dd1880 [virNetServer], client=0x564bb3e80030 [virNetServerClient], msg=0x564bb3e81620) at ../src/rpc/virnetserverprogram.c:302
#19 0x00007fca133796d4 in virNetServerProcessMsg
(msg=<optimized out>, prog=<optimized out>, client=<optimized out>, srv=0x564bb3dd1880 [virNetServer]) at ../src/rpc/virnetserver.c:140
#20 virNetServerHandleJob (jobOpaque=0x564bb3e7fd50, opaque=0x564bb3dd1880) at ../src/rpc/virnetserver.c:160
#21 0x00007fca132b8eaf in virThreadPoolWorker (opaque=<optimized out>) at ../src/util/virthreadpool.c:164
#22 0x00007fca132b84f5 in virThreadHelper (data=<optimized out>) at ../src/util/virthread.c:256
#23 0x00007fca12c362ba in start_thread (arg=<optimized out>) at pthread_create.c:442
#24 0x00007fca12cc0460 in clone3 () at ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
----
In order to work around the problem this is the hack I used (to get things to work), but clearly it is no solution:
diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c
index 5df48af60c..e22d3cb5c5 100644
--- a/src/util/virnetdev.c
+++ b/src/util/virnetdev.c
@@ -3616,7 +3616,7 @@ virNetDevGenerateName(char **ifname, virNetDevGenNameType type)
g_autofree char *try = NULL;
int id = 0;
- VIR_WITH_OBJECT_LOCK_GUARD(&virNetDevGenNames[type].mutex) {
+ /* VIR_WITH_OBJECT_LOCK_GUARD(&virNetDevGenNames[type].mutex) */ {
id = ++virNetDevGenNames[type].lastID;
/* reset before overflow */
----
With this applied things run fine for me, install is successful and domain is functional.
Ciao,
Claudio
--
Claudio Fontana
Engineering Manager Virtualization, SUSE Labs Core
SUSE Software Solutions Italy Srl
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