Bug 599590
| Summary: | [vdsm] [libvirt intg] libvirtd hangs during concurrent bi-directional migration | ||||||||
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| Product: | Red Hat Enterprise Linux 6 | Reporter: | Haim <hateya> | ||||||
| Component: | libvirt | Assignee: | Chris Lalancette <clalance> | ||||||
| Status: | CLOSED CURRENTRELEASE | QA Contact: | Virtualization Bugs <virt-bugs> | ||||||
| Severity: | high | Docs Contact: | |||||||
| Priority: | low | ||||||||
| Version: | 6.0 | CC: | bazulay, berrange, dallan, danken, hateya, hbrock, iheim, jdenemar, mgoldboi, mjenner, xen-maint, yeylon, ykaul | ||||||
| Target Milestone: | rc | Keywords: | TestBlocker | ||||||
| Target Release: | --- | ||||||||
| Hardware: | All | ||||||||
| OS: | Linux | ||||||||
| Whiteboard: | vdsm & libvirt integration | ||||||||
| Fixed In Version: | libvirt-0_8_1-17_el6 | Doc Type: | Bug Fix | ||||||
| Doc Text: | Story Points: | --- | |||||||
| Clone Of: | |||||||||
| : | 630614 (view as bug list) | Environment: | |||||||
| Last Closed: | 2010-11-11 14:48:53 UTC | Type: | --- | ||||||
| Regression: | --- | Mount Type: | --- | ||||||
| Documentation: | --- | CRM: | |||||||
| Verified Versions: | Category: | --- | |||||||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||||
| Cloudforms Team: | --- | Target Upstream Version: | |||||||
| Embargoed: | |||||||||
| Bug Depends On: | |||||||||
| Bug Blocks: | 581275, 609432, 630614 | ||||||||
| Attachments: |
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> attached information:
>
> 1) libvirtd.log on both servers (white-vdse and pink-nehalem2)
> 2) gdb trace information (attached to hang process
Seems like you wanted to attach libvirtd log but forgot to do so in the end. Could you, please, provide it?
The problem is this.. With PEER2PEER migration, the source libvirtd makes API calls into the destination libvirtd. Unfortunately it is holding the qemu driver lock, and virDomainObj lock while doing this. If the other libvirtd is also trying to call back into this libvirtd, it also holds the qemu driver + domain obj locks. Deadlock is ensured As we do when interacting with the QEMU monitor, we need to add calls to BeginJob/EndJob and also an equivalent to EnterMonitor/LeaveMonitor around every API call to the remote libvirtd. This ensures we release all locks while doing API calls. This impacts the methods doPeer2PeerMigrate, doNonTunnelMigrate, doTunnelMigrate and doTunnelSendAll. Looking at the code, I think we already have the BeginJob/EndJob calls (though it's not exactly trivial to follow it). When we come into qemudDomainMigratePerform(), we lock the driver, then lock the virDomainObj (via virDomainFindByUUID()), then call qemuDomainObjBeginJobWithDriver(). After that we call doPeer2PeerMigrate(), so we already have the job "started". However, qemuDomainObjBeginJobWithDriver just starts the job; it is still holding onto the driver lock and the domain obj lock after it exits. What we need is exactly what Dan mentioned in the second part of his comment; an equivalent to EnterMonitor/LeaveMonitor, called something like "EnterRemoteLibvirt/LeaveRemoteLibvirt", that will take an additional reference (to keep things safe) and drop both the driver lock and the obj lock. Chris Lalancette Patch posted upstream: https://www.redhat.com/archives/libvir-list/2010-July/msg00346.html Chris Lalancette Committed to upstream libvirt as: f0c8e1cb3774d6f09e2681ca1988bf235a343007 I'm working on a RHEL-6 backport now. Chris Lalancette Created attachment 433259 [details]
Backport of libvirt upstream patch to fix concurrent p2p migrations
libvirt-0_8_1-17_el6 has been built in RHEL-6-candidate with the fix. Dave verified running with the following versions: qemu-kvm-0.12.1.2-2.97.el6.x86_64 vdsm-4.9-11.el6.x86_64 2.6.32-52.el6.x86_64 executed several concurrent bi-directional migrations, all vms were successfully migrated to their destination host, virsh didn't hang. fixed. and of course libvirt version: libvirt-0.8.1-19.el6.x86_64 Red Hat Enterprise Linux 6.0 is now available and should resolve the problem described in this bug report. This report is therefore being closed with a resolution of CURRENTRELEASE. You may reopen this bug report if the solution does not work for you. |
Created attachment 419407 [details] gdb logs of both server during the hang Description of problem: trying out concurrent bi-directional migration causes libvirt to hang. this is reproducible and happened 3 times so far. scenario goes as follows: - 2 running hosts - 2 running vms == vm 1 is on host 1 == vm 2 is on host 2 - using rhev-m - perform concurrent migration meaning: == vm 1 which runs on host 1 is destined to run on host 2 == vm 2 which runs on host 2 is destined to run on host 1 attached information: 1) libvirtd.log on both servers (white-vdse and pink-nehalem2) 2) gdb trace information (attached to hang process vdsm-4.9-7.el6.x86_64 libvirt-0.8.1-7.el6.x86_64 qemu-kvm-0.12.1.2-2.68.el6.x86_64 2.6.32-31.el6.x86_64