On Wed, Jul 10, 2024 at 05:05:06AM +0200, David Hildenbrand wrote: > On 09.07.24 04:17, Jason A. Donenfeld wrote: > > Hi David, > > > > On Mon, Jul 08, 2024 at 10:21:09PM +0200, David Hildenbrand wrote: > >> BTW, I was just trying to understand how MADV_FREE + MAP_DROPPABLE would > >> behave without any swap space around. > >> > >> Did you experiment with that? > > > > You mean on a system without any swap configured? That's actually my > > primary test environment for this. It behaves as expected: when ram > > fills up and the scanner is trying to reclaim what it can, > > folio_test_swapbacked(folio) is false, and the memory gets freed. After, > > reads fault in a zero page. So it's working as expected. > > Okay, just to be clear: no swap/zram/zswap. The reclaim code regarding > not scanning anonymous memory without swap was a bit confusing. Right, no swap, as boring a system as can be. I've experimented with that behavior on my swap-less 64GB thinkpad, as well as on little special purpose VMs, where I hacked the VM_DROPPABLE test code into the wireguard test suite. Jason
