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Bug 1686615 - QEMU IOTEST 153 fails intermittently with "failed to get 'write' lock"
Summary: QEMU IOTEST 153 fails intermittently with "failed to get 'write' lock"
Keywords:
Status: POST
Alias: None
Product: Red Hat Enterprise Linux Advanced Virtualization
Classification: Red Hat
Component: qemu-kvm
Version: 8.1
Hardware: x86_64
OS: Linux
unspecified
unspecified
Target Milestone: rc
: 8.1
Assignee: Sergio Lopez
QA Contact: Tingting Mao
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2019-03-07 20:38 UTC by Karen Mezick
Modified: 2019-04-10 13:43 UTC (History)
15 users (show)

Fixed In Version: qemu-4.0
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed:
Type: Bug
Target Upstream Version:


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Comment 4 Sergio Lopez 2019-03-14 10:45:16 UTC
I think I know what's happening here. Test 153 has a number of actions that must be executed sequentially in an specific order. But some of those actions are driven using "_send_qemu_cmd()" without specifying an expected return value. The absence of this return value, means this function writes to QMP without waiting for an answer. This means that, while unlikely, the next action can be executed while the first one didn't have yet an effect.

I suppose this behavior can be exacerbated on machines with limited resources or highly loaded.

I'll produce a patch to discuss this possibility upstream.

Thanks,
Sergio.

Comment 6 Sergio Lopez 2019-04-10 13:43:48 UTC
Upstream has a patch addressing this issue, included in qemu-4.0:

https://lists.nongnu.org/archive/html/qemu-devel/2019-03/msg05181.html


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