Quoting Andi Shyti (2020-03-27 16:27:27) > Hi Chris, > > On Thu, Mar 26, 2020 at 02:27:27PM +0000, Chris Wilson wrote: > > Userptr causes lockdep to complain when we are using the aliasing-ppgtt > > (and ggtt, but for that it is rightfully so to complain about) in that > > when we revoke the userptr we take a mutex which we also use to revoke > > the mmaps. However, we only revoke mmaps for GGTT bindings and we never > > allow userptr to create a GGTT binding so the warning should be false > > and is simply caused by our conflation of the aliasing-ppgtt with the > > ggtt. So lets try treating the binding into the aliasing-ppgtt as a > > separate lockclass from the ggtt. The downside is that we are > > deliberately suppressing lockdep;s ability to warn us of cycles. > ^^^^ > typo > > > > > Closes: https://gitlab.freedesktop.org/drm/intel/issues/478 > > I'm not a big fan of links in commit messages, I think they would > be forbidden by law, but I'm not being picky on that. I'm lazy, I take clickable links. > I don't know, thogh, why your S-o-b is missing. I felt uncomfortable with this hack, but it passes CI (but it may be suppressing too much -- I think the code is safe at the moment, but we may lose our sensitivity to future bugs). > > > --- > > drivers/gpu/drm/i915/i915_vma.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c > > index 191577a98390..9f4a31cd54ac 100644 > > --- a/drivers/gpu/drm/i915/i915_vma.c > > +++ b/drivers/gpu/drm/i915/i915_vma.c > > @@ -914,7 +914,8 @@ int i915_vma_pin(struct i915_vma *vma, u64 size, u64 alignment, u64 flags) > > wakeref = intel_runtime_pm_get(&vma->vm->i915->runtime_pm); > > > > /* No more allocations allowed once we hold vm->mutex */ > > - err = mutex_lock_interruptible(&vma->vm->mutex); > > + err = mutex_lock_interruptible_nested(&vma->vm->mutex, > > + !(flags & PIN_GLOBAL)); > > if (err) > > goto err_fence; > > > > @@ -1320,7 +1321,7 @@ int i915_vma_unbind(struct i915_vma *vma) > > if (err) > > goto out_rpm; > > > > - err = mutex_lock_interruptible(&vm->mutex); > > + err = mutex_lock_interruptible_nested(&vma->vm->mutex, !wakeref); > > looks reasonable to me. Thanks! > > Are you planning to push it? You have my review for this. I'm planning on adding a comment to attempt to justify itself and then push. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
