tmpfs doesn't update free memory stats?

[Jacek Kopecky]

 Hello. 8-)
 I'm not in the list, please cc your replies to me.
 After upgrading to 2.4.4 I started using tmpfs for /tmp and I
noticed a strange behavior:

 dd if=/dev/zero of=blah bs=1024 count=102400
	# increased my used swap space by approx. 100MiB (correct)
 rm blah
	# did not decrease it back

 Multiple retries showed what looked like a random behavior of
the used swap stats. Is this a correct behavior? Should the swap
stats be dismissed as 'unreliable'? I expected that when creating
a 100MiB file in memory it should increase the swap (or memory)
usage by cca 100MiB and that removing a file from tmpfs means
freeing the memory.
 Best regards

                            Jacek Kopecky
                               Idoox