On 2025-03-07 at 12:31:25 +0100, Chris Wilson wrote: > Quoting Mikolaj Wasiak (2025-03-07 08:44:29) > > Hi Krzysztof, > > > > On 2025-03-05 at 17:31:49 +0100, Krzysztof Niemiec wrote: > > > Don't we run into the same issue as in V1, meaning we use an unknown > > > current->active_mm (since we run in a kthread, and cannot control it) to > > > use as the current->mm? Maybe a better approach would be to create a new > > > mm for the duration of the test, similarly to how the patch Janusz > > > mentioned does it? (51104c19d857) > > > > As per discussion with Chris, using active_mm is the correct way of > > enabling current->mm in kthread. On the other hand it may also expose > > issues with underlying tests because they didn't previously run on such > > hardware. I think potential fixes to those tests should be addressed in > > separate patch. > > We've looked at the tests, and they should all be finding unused space > in the mm and cleaning up after themselves... > > If we put on our paranoia hats, the biggest problem with borrowing > userspace's mm is that it gives them temporary insight into whatever > we place into that mm. We don't expose any data, unless by error... > Not sure how much effort we want to put on making the selftests paranoia > proof, but that (and the surety of cleaning up afterwards) would be a > good argument for creating a temporary mm for our use. > -Chris I still don't know if it would be feasible to use methods that are exposed only to kunit to run our selftest. Do you think we should go that way? Mikołaj
