Quoting Chris Wilson (2017-12-15 10:09:02) > We want to exclude any GGTT objects from being present on our internal > lists to avoid the deadlock we may run into with our requirement for > struct_mutex during invalidate. However, if the gup_fast fails, we put > the userptr onto the workqueue and mark it as active, so that we > remember to serialise the worker upon mmu_invalidate. > > v2: Hold mmap_sem to prevent modifications to the mm while we probe and > add ourselves to the interval-tree for notificiation. > v3: Rely on mmap_sem for a simpler patch. > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104209 > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > Cc: Michał Winiarski <michal.winiarski@xxxxxxxxx> > --- > drivers/gpu/drm/i915/i915_gem_userptr.c | 42 +++++++++++++++++++++++++++++++-- > 1 file changed, 40 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c > index 382a77a1097e..f879c76e46ee 100644 > --- a/drivers/gpu/drm/i915/i915_gem_userptr.c > +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c > @@ -598,6 +598,37 @@ __i915_gem_userptr_get_pages_schedule(struct drm_i915_gem_object *obj) > return ERR_PTR(-EAGAIN); > } > > +static int > +probe_range(struct mm_struct *mm, unsigned long addr, unsigned long len) > +{ > + const unsigned long end = addr + len; > + struct vm_area_struct *vma; > + int ret = -EFAULT; > + > + for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) { > + if (vma->vm_start > addr) > + break; > + > + /* > + * Exclude any VMA that is backed only by struct_page, i.e. > + * IO regions that include our own GGTT mmaps. We cannot handle > + * such ranges, as we may encounter deadlocks around our > + * struct_mutex on mmu_invalidate_range. > + */ > + if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) > + break; > + > + if (vma->vm_end >= end) { > + ret = 0; > + break; > + } > + > + addr = vma->vm_end; > + } > + > + return ret; > +} > + > static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj) > { > const int num_pages = obj->base.size >> PAGE_SHIFT; > @@ -632,9 +663,15 @@ static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj) > return -EAGAIN; > } > > - pvec = NULL; > - pinned = 0; > + /* Quickly exclude any invalid VMA */ > + down_read(&mm->mmap_sem); Regardless, mmap_sem is not allowed here, as we may be underneath struct_mutex and a mmap_sem from a pagefault. Please look the other way as I investigate nesting... -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
