maybe a virtio-balloon-device issue ?

[Mario Smarduch <m.smarduch@samsung.com>]

Hi,

I'm looking into qemu/balloon driver VM overcommit. I noticed
virtio-balloon driver will take any setting from virtio-balloon-device
to the point Guest dies.

For a 1G guest
$ sudo echo balloon 100 | socat - tcp4-connect:127.0.0.1:4444

you get (same with libvirt setmem)

root@localhost:~# free
-bash: fork: Cannot allocate memory
root@localhost:~# ps
-bash: fork: Cannot allocate memory

$ sudo info balloon | socat ... - confirms setting

The balloon driver has been there for a while, not sure what I'm missing?

virtio-balloon-device provide free memory, i.e., - externally accessible
to host.  But this appears more like a hint for an inflate request, snmp
mibs
provide more detailed resource info then that.

I'm wondering if the driver should  not have some heuristic
check for an inflate request so it doesn't over inflate?  Similar to
kernel overcommit.

Thanks.