pfSense

I have not seen that happen here when I was testing this initially, but I don't currently have any systems with RAM disks active to confirm right this moment.

I was able to replicate this on an ARM system (SG-3100).

Kernel Memory before activating RAM disks:

vm.kmem_map_free: 131039232
vm.kmem_map_size: 197795840
vm.kmem_size_scale: 3
vm.kmem_size_max: 328833434
vm.kmem_size_min: 12582912
vm.kmem_zmax: 65536
vm.kmem_size: 328835072

Kernel Memory after activating RAM disks (40M /tmp, 60M /var):

vm.kmem_map_free: 41320448
vm.kmem_map_size: 287514624
vm.kmem_size_scale: 3
vm.kmem_size_max: 328833434
vm.kmem_size_min: 12582912
vm.kmem_zmax: 65536
vm.kmem_size: 328835072

Disk sizes/usage:

: df -h /tmp /var
Filesystem    Size    Used   Avail Capacity  Mounted on
/dev/md0       38M    336K     35M     1%    /tmp
/dev/md1       58M     19M     34M    36%    /var

Free Before - Free After = 89718784

So the free amount went down by about 90M but the RAM disks total 100M. I'm not exactly sure why there is a discrepancy in the numbers. It's close but not quite the same.

If we add the configured RAM disk size to the vm.kmem_map_free value before calculating if things fit it should help, but there is still some danger of the calculation being incorrect.

Applied in changeset 355aa65e684431fe435dcf51c92f17659b5b000d.

Calculation is correct on 2.4.5-p1 internal testing snapshot. RAM disk space is accounted for properly and used space is not counted against total when saving as it was before.