installer creates swap partition fractionally smaller than specified

[James Ferguson]

Binary package hint: partman-auto

Release: Lucid
Expected: swap size to be at least the size requested.
Actual: With a preseed file specifying swap partition to be 100% of memory, the result is consistently 97.5% of memory, for various memory sizes.

Here is the relevant part of the preseed file:

 d-i partman-auto/expert_recipe string \
                                       \
   dell :: \
                                       \
       500 10000 1000000 ext4 \
       $primary{ } \
       method{ format } \
       format{ } \
       use_filesystem{ } \
       filesystem{ ext4 } \
       mountpoint{ / } . \
                                       \
       64 512 100% linux-swap \
       method{ swap } \
       format{ } \
       .

And here is a representative result. I have performed many installations with varying memory sizes and these settings and the result is consistently less than free memory.

$ free
             total used free shared buffers cached
Mem: 1801528 773564 1027964 0 30684 324192
-/+ buffers/cache: 418688 1382840
Swap: 1758200 0 1758200