While running a container with a memory constraint, I found that the amount of memory that we are able to use is really small. In the following example I am assigning a container a memory of 256m and using only 100m and the result is that the container is running out of memory

$ docker run --runtime kata-runtime --rm -m 256m debian perl -e 'my $name = " "x1024x1024x100;'                                 
Out of memory!

If I look inside the container, it says that I have the following amount of memory

$ docker run -ti --runtime kata-runtime -m 256m debian bash
root@384678345bcd:/# cat /proc/meminfo
MemTotal:         242348 kB
MemFree:          207196 kB
MemAvailable:     207228 kB

While doing the same with runc the issue is not present

$ docker run --runtime runc --rm -m 256m debian perl -e 'my $name = " "x1024x1024x250;'

This is the configuration that I am using
kata-runtime : 1.1.0
commit : ff7b4f6
OCI specs: 1.0.1
kata-agent version 1.1.0-17b44df35a174c09966cf9d2ccc8472a597feda1
kata-proxy version 1.1.0-7e2a93d1931d814debfcff2846b1514af1b9601d
kata-shim version 1.1.0-6ddca0334d0e8dee6e1e00f0c120fde4b8c1c176
Docker version 18.03.1-ce, build 9ee9f40