Description of problem: Stopping a kvm-enabled virtual machine does not free the memory allocated to that machine, the memory is essentially lost until the kernel is rebooted. Looks like this: [sun@lain ~/xen/xos :) 38]$ free total used free shared buffers cached Mem: 3084812 2362980 721832 0 54752 1417440 -/+ buffers/cache: 890788 2194024 Swap: 1015800 0 1015800 [sun@lain ~/xen/xos :) 40]$ sudo ./start (this essentially starts qemu-kvm with the necessary parameters, this machine has 256MB RAM allocated) config qemu network with bridge for tap1 ^C [sun@lain ~/xen/xos :( (1) 41]$ free total used free shared buffers cached Mem: 3084812 2615736 469076 0 55368 1416820 -/+ buffers/cache: 1143548 1941264 Swap: 1015800 0 1015800 As can be seen, the "used" memory has increased by roughly 256MB. Version-Release number of selected component (if applicable): kvm-63-2.fc9.i386 kernel-PAE-2.6.25-0.136.rc6.git5.fc9.i686 How reproducible: Always Steps to Reproduce: 1. see above 2. 3. Actual results: Memory for the virtual machine is never freed Expected results: Memory for the virtual machine is freed after machine shutdown Additional info:
Bug in 2.6.25-fc5 kernel, patch on kvm-devel http://article.gmane.org/gmane.comp.emulators.kvm.devel/14867
As Dan says, this is being discussed on kvm-devel. Although apparently that patch isn't quite enough to fix it. Once there's a fix in the thread, I'll make sure it gets into our kernels.
Should be fixed with current kernels (we added the patch, then took in the upstream version)