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Bug 1999114

Summary: qemu-kvm: ../util/iov.c:428: qemu_iovec_init_extended: Assertion `mid_qiov->niov <= IOV_MAX' failed.
Product: Red Hat Enterprise Linux Advanced Virtualization Reporter: Jean-Louis Dupond <jean-louis>
Component: qemu-kvmAssignee: Virtualization Maintenance <virt-maint>
qemu-kvm sub component: Storage QA Contact: qing.wang <qinwang>
Status: CLOSED DUPLICATE Docs Contact:
Severity: high    
Priority: unspecified CC: jinzhao, juzhang, qinwang, virt-maint
Version: 8.5Flags: pm-rhel: mirror+
Target Milestone: rc   
Target Release: 8.5   
Hardware: x86_64   
OS: Unspecified   
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Clone Of: Environment:
Last Closed: 2021-08-31 01:29:15 UTC Type: Bug
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Jean-Louis Dupond 2021-08-30 12:50:11 UTC 
Description of problem:
When further debugging issue bz#1999051 , I did some write actions on a test VM to be able to simulate the issue.

But while doing this. The VM crashed like 3 our of 4 times with the following message:
qemu-kvm: ../util/iov.c:428: qemu_iovec_init_extended: Assertion `mid_qiov->niov <= IOV_MAX' failed.

This was when running a 'dd if=/dev/zero of=test' inside the VM.
It happens after a few seconds.


Version-Release number of selected component (if applicable):
qemu-kvm-6.0.0-26.el8s.x86_64

How reproducible:
Disk is only 10GB, and almost always crashes before I could write 10G.

Steps to Reproduce:
1. Create a VM with VirtIO disk
2. Run a  'dd if=/dev/zero of=test'
3. It will crash
Comment 1 John Ferlan 2021-08-30 20:28:39 UTC 
This would seem to be related to qemu commit 4c002cef0 (https://git.qemu.org/?p=qemu.git;a=commit;h=4c002cef0e9abe7135d7916c51abce47f7fc1ee2)

There is also qemu commit 87ab88025 (https://git.qemu.org/?p=qemu.git;a=commit;h=87ab88025247b893aad5071fd38301b67be76d1a) which resolves another bug in the series

If you're willing to try the upstream qemu to see if it fixes things (both issues) that could be an interesting data point.
Comment 2 qing.wang 2021-08-31 01:27:21 UTC 
This issue should be same reason with 
Bug 1994494 - VM remains in paused state when trying to write on a resized disk resides on iscsi


It will hit crash when using qcow2 format.

https://bugzilla.redhat.com/show_bug.cgi?id=1994494#c66
Comment 3 qing.wang 2021-08-31 01:29:15 UTC 

*** This bug has been marked as a duplicate of bug 1994494 ***