Hey Andrew, On Tue, Jul 02, 2024 at 12:42:54AM -0700, Andrew Morton wrote: > The patch is impressively comment-free. It is a little harsh to make > readers go poking around in the git history to figure out what > VM_DROPPABLE is, and why it exists. Sure, I'll add some comments to the conditionals added to make it more clear. > Seems hard to test that this mode is working correctly. Can you think > of a way for userspace to check this? And if so, add it to selftests? I've got a pretty straight forward test I've been using during my own testing that I can add to the vgetrandom_alloc() selftest (which exposes these code paths). It works fairly reliably. Basically, one process keeps checking to see if the memory has been dropped, while the other consumes memory a page at a time. Pretty soon (depending on how much ram you have), the memory gets dropped, and this is detected, and the test completes with a pass. I'll have this in v+1 of this series. Jason
