Lately I've noticing entries like this one in the kern.log of one of my servers: Feb 16 00:24:05 aramis kernel: swapper: page allocation failure. order:0, mode:0x20 This is what I'd like to know: What exactly does that message mean? Is my server running out of memory? The swap usage is quite low (less than 10%), and so far I haven't noticed any processes being killed because of lack of memory. Additional information: The server is a Xen instance (DomU) running Debian 6.0 It has 512 MB of RAM and a 512 MB swap partition CPU load inside the virtual machine shows an average of 0.25