Bug #13726: QEMU hangs after creating snapshot and stopping VM - rbd - Ceph

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Bug #13726

closed

QEMU hangs after creating snapshot and stopping VM

Added by Jason Dillaman over 8 years ago. Updated over 8 years ago.

Status:

Resolved

Priority:

Normal

Assignee:

Jason Dillaman

Target version:

% Done:

Source:

Community (user)

Tags:

Backport:

hammer,infernalis

Regression:

Severity:

3 - minor

Reviewed:

Affected Versions:

ceph-qa-suite:

Pull request ID:

Crash signature (v1):

Crash signature (v2):

Description

When RBD cache is disabled, taking a snapshot and stopping the VM results in a hung QEMU process. Setting "rbd_non_blocking_aio" to false apparently resolves the issue.

http://www.spinics.net/lists/ceph-devel/msg27170.html

Files

ceph.client.log (1010 KB) ceph.client.log

alexandre derumier, 11/09/2015 02:01 PM

Related issues 3 (0 open — 3 closed)

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Updated by alexandre derumier over 8 years ago

File ceph.client.log ceph.client.log added

I have attached the client log,

the snapshot create command was :

rbd -p pooltest --image vm-162-disk-1 snap create --snap snap1

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Updated by Jason Dillaman over 8 years ago

In-flight AIO read request forces an image refresh due to out-of-band snapshot creation. Detecting the newly created snapshot forces librbd to flush all in-flight ops. If there are no in-flight ops to flush, it will enqueue a completion on the thread pool. However, the thread pool will be blocked handling the AIO request waiting for the flush to complete.

The synchronous ImageCtx::flush_async_operations() method cannot use async callbacks.

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