On Tue, Aug 20, 2019 at 05:18:10PM +0200, Daniel Vetter wrote: > On Tue, Aug 20, 2019 at 10:34:18AM -0300, Jason Gunthorpe wrote: > > On Tue, Aug 20, 2019 at 10:19:02AM +0200, Daniel Vetter wrote: > > > We need to make sure implementations don't cheat and don't have a > > > possible schedule/blocking point deeply burried where review can't > > > catch it. > > > > > > I'm not sure whether this is the best way to make sure all the > > > might_sleep() callsites trigger, and it's a bit ugly in the code flow. > > > But it gets the job done. > > > > > > Inspired by an i915 patch series which did exactly that, because the > > > rules haven't been entirely clear to us. > > > > > > v2: Use the shiny new non_block_start/end annotations instead of > > > abusing preempt_disable/enable. > > > > > > v3: Rebase on top of Glisse's arg rework. > > > > > > v4: Rebase on top of more Glisse rework. > > > > > > Cc: Jason Gunthorpe <j...@ziepe.ca> > > > Cc: Andrew Morton <a...@linux-foundation.org> > > > Cc: Michal Hocko <mho...@suse.com> > > > Cc: David Rientjes <rient...@google.com> > > > Cc: "Christian König" <christian.koe...@amd.com> > > > Cc: Daniel Vetter <daniel.vet...@ffwll.ch> > > > Cc: "Jérôme Glisse" <jgli...@redhat.com> > > > Cc: linux...@kvack.org > > > Reviewed-by: Christian König <christian.koe...@amd.com> > > > Reviewed-by: Jérôme Glisse <jgli...@redhat.com> > > > Signed-off-by: Daniel Vetter <daniel.vet...@intel.com> > > > mm/mmu_notifier.c | 8 +++++++- > > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > > > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > > > index 538d3bb87f9b..856636d06ee0 100644 > > > +++ b/mm/mmu_notifier.c > > > @@ -181,7 +181,13 @@ int __mmu_notifier_invalidate_range_start(struct > > > mmu_notifier_range *range) > > > id = srcu_read_lock(&srcu); > > > hlist_for_each_entry_rcu(mn, &range->mm->mmu_notifier_mm->list, hlist) { > > > if (mn->ops->invalidate_range_start) { > > > - int _ret = mn->ops->invalidate_range_start(mn, range); > > > + int _ret; > > > + > > > + if (!mmu_notifier_range_blockable(range)) > > > + non_block_start(); > > > + _ret = mn->ops->invalidate_range_start(mn, range); > > > + if (!mmu_notifier_range_blockable(range)) > > > + non_block_end(); > > > > If someone Acks all the sched changes then I can pick this for > > hmm.git, but I still think the existing pre-emption debugging is fine > > for this use case. > > Ok, I'll ping Peter Z. for an ack, iirc he was involved. > > > Also, same comment as for the lockdep map, this needs to apply to the > > non-blocking range_end also. > > Hm, I thought the page table locks we're holding there already prevent any > sleeping, so would be redundant? But reading through code I think that's > not guaranteed, so yeah makes sense to add it for invalidate_range_end > too. I'll respin once I have the ack/nack from scheduler people.
So I started to look into this, and I'm a bit confused. There's no _nonblock version of this, so does this means blocking is never allowed, or always allowed? From a quick look through implementations I've only seen spinlocks, and one up_read. So I guess I should wrape this callback in some unconditional non_block_start/end, but I'm not sure. Thanks, Daniel > > Anyhow, since this series has conflicts with hmm.git it would be best > > to flow through the whole thing through that tree. If there are no > > remarks on the first two patches I'll grab them in a few days. > > Thanks, Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx