ci/kernel: enable ZRAM on all archs

Let's enable ZRAM with 2G. Should help prevent peak OOM scenarios.

For more info see: https://www.kernel.org/doc/html/latest/admin-guide/blockdev/zram.html

Reviewed-by: Eric Engestrom <eric@igalia.com>
Signed-off-by: David Heidelberg <david.heidelberg@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19535>

.gitlab-ci/common/init-stage2.sh

@@ -45,6 +45,16 @@ set -ex
     echo -n $HWCI_KERNEL_MODULES | xargs -d, -n1 /usr/sbin/modprobe
 }
 
+# Set up ZRAM
+HWCI_ZRAM_SIZE=2G
+if zramctl --find --size $HWCI_ZRAM_SIZE -a zstd; then
+    mkswap /dev/zram0
+    swapon /dev/zram0
+    echo "zram: $HWCI_ZRAM_SIZE activated"
+else
+    echo "zram: skipping, not supported"
+fi
+
 #
 # Load the KVM module specific to the detected CPU virtualization extensions:
 # - vmx for Intel VT