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Description of problem:
Example: host memory size 8G. hotplug 14G size memory to qemu-kvm. 

result:
(qemu) object_add memory-backend-ram,id=mem1,size=15G
Cannot set up guest memory 'mem1': Cannot allocate memory

From QE pov. qemu-kvm should prevent this operation(As overcommit). and print a friendly information.  At least, qemu-kvm process shouldn't quit.  I am not sure upstream tool if have resolved this issue.  If need.  I will test it with virsh.

Version-Release number of selected component (if applicable):
qemu-kvm-rhev-2.1.2-13.el7.x86_64
3.10.0-208.el7.x86_64

How reproducible:
100％

Steps to Reproduce:
1./usr/libexec/qemu-kvm -M pc -enable-kvm -m 4G,slots=4,maxmem=80G -monitor stdio

2.(qemu) object_add memory-backend-ram,id=mem1,size=14G
3.

Actual results:
qemu-kvm-rhev process quit
Cannot set up guest memory 'mem1': Cannot allocate memory

Expected results:


Additional info:

fixed upstream, please retest when 7.2 build is available

Moving to modified state as it is not TestOnly.

reproduce:
host kernel:3.10.0-267.el7.x86_64
host qemu:  qemu-kvm-rhev-2.1.2-21.el7.x86_64

QE retested this bug on the above environment,then got the same result.
So, the bug is reproduced on the above environment.


verify:
host kernel:3.10.0-267.el7.x86_64
host qemu:  qemu-kvm-rhev-2.3.0-4.el7.x86_64

QE retested this bug on the above environment. After hot-plugging memory size overcommit host memory, qemu-kvm process didn't quit and printed a friendly error info.
So, the bug fixed.

Based on Comment 5, set this bug to VERIFIED.

Best regards,
Huiqing

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2015-2546.html