Where did all my memory go?

[Ivan Gyurdiev]

So I decided to hunt for bugs (which there's a lot of...) by running rpm 
-Va to see which packages conflict, and what other damage is there in 
the database.

Then the computer got slower, and slower, and slower....
And several hours later it got done (I have a lot of packages, I don't 
know how fast it should be)

Now I see:

             total       used       free     shared    buffers     cached
Mem:       1025512    1016696       8816          0       1668      39980
-/+ buffers/cache:     975048      50464
Swap:       524152     261924     262228

There were prelink/rpmv zombies which I killed.
Firefox and thunderbir were eating a lot of memory as usual, but I 
killed those too.
The result above is afterwards, with not much running other than a 
standard gnome desktop.
The top process by resident memory is eating 40MB or so.

Kernel (1959 + madwifi + Nvidia + Steve' Grubb's lspp things):
2.6.15-1.1959.2.1_FC5.lspp.9

slabtop:
12535365 12535330  99%    0.05K 187095       67    748380K size-32
869924 869896  99%    0.09K  19771       44     79084K size-64
 93632  93622  99%    0.05K   1216       77      4864K avtab_node
 14500   4918  33%    0.15K    580       25      2320K size-128
 11210  10221  91%    0.20K    590       19      2360K vm_area_struct

What's using up all the memory?