On Tue, Aug 20, 2019 at 10:18:59AM +0200, Daniel Vetter wrote: > This is a similar idea to the fs_reclaim fake lockdep lock. It's > fairly easy to provoke a specific notifier to be run on a specific > range: Just prep it, and then munmap() it. > > A bit harder, but still doable, is to provoke the mmu notifiers for > all the various callchains that might lead to them. But both at the > same time is really hard to reliable hit, especially when you want to > exercise paths like direct reclaim or compaction, where it's not > easy to control what exactly will be unmapped. > > By introducing a lockdep map to tie them all together we allow lockdep > to see a lot more dependencies, without having to actually hit them > in a single challchain while testing. > > On Jason's suggestion this is is rolled out for both > invalidate_range_start and invalidate_range_end. They both have the > same calling context, hence we can share the same lockdep map. Note > that the annotation for invalidate_ranage_start is outside of the > mm_has_notifiers(), to make sure lockdep is informed about all paths > leading to this context irrespective of whether mmu notifiers are > present for a given context. We don't do that on the > invalidate_range_end side to avoid paying the overhead twice, there > the lockdep annotation is pushed down behind the mm_has_notifiers() > check. > > v2: Use lock_map_acquire/release() like fs_reclaim, to avoid confusion > with this being a real mutex (Chris Wilson). > > v3: Rebase on top of Glisse's arg rework. > > v4: Also annotate invalidate_range_end (Jason Gunthorpe) > Also annotate invalidate_range_start_nonblock, I somehow missed that > one in the first version. > > Cc: Jason Gunthorpe <jgg@xxxxxxxx> > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: David Rientjes <rientjes@xxxxxxxxxx> > Cc: "Jérôme Glisse" <jglisse@xxxxxxxxxx> > Cc: Michal Hocko <mhocko@xxxxxxxx> > Cc: "Christian König" <christian.koenig@xxxxxxx> > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> > Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> > Cc: linux-mm@xxxxxxxxx > Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> > --- > include/linux/mmu_notifier.h | 8 ++++++++ > mm/mmu_notifier.c | 9 +++++++++ > 2 files changed, 17 insertions(+) Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Jason _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
