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. v4: Mark up the mmap_sem nesting v5: Don't deactivate on -EAGAIN as that means the worker is queued Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104209 Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursu...@intel.com> Cc: Michał Winiarski <michal.winiar...@intel.com> --- drivers/gpu/drm/i915/i915_gem_userptr.c | 55 +++++++++++++++++++++++++++------ 1 file changed, 45 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c index 382a77a1097e..b16b8e226e40 100644 --- a/drivers/gpu/drm/i915/i915_gem_userptr.c +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c @@ -598,13 +598,43 @@ __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; struct mm_struct *mm = obj->userptr.mm->mm; struct page **pvec; struct sg_table *pages; - bool active; int pinned; /* If userspace should engineer that these pages are replaced in @@ -634,7 +664,6 @@ static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj) pvec = NULL; pinned = 0; - if (mm == current->mm) { pvec = kvmalloc_array(num_pages, sizeof(struct page *), GFP_KERNEL | @@ -647,19 +676,25 @@ static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj) pvec); } - active = false; + down_read_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING); if (pinned < 0) { pages = ERR_PTR(pinned); pinned = 0; - } else if (pinned < num_pages) { - pages = __i915_gem_userptr_get_pages_schedule(obj); - active = pages == ERR_PTR(-EAGAIN); + } else if (pinned < num_pages && + probe_range(mm, obj->userptr.ptr, obj->base.size)) { + pages = ERR_PTR(-EFAULT); + } else if (__i915_gem_userptr_set_active(obj, true)) { + pages = ERR_PTR(-EAGAIN); } else { - pages = __i915_gem_userptr_alloc_pages(obj, pvec, num_pages); - active = !IS_ERR(pages); + if (pinned < num_pages) + pages = __i915_gem_userptr_get_pages_schedule(obj); + else + pages = __i915_gem_userptr_alloc_pages(obj, + pvec, num_pages); + if (IS_ERR(pages) && pages != ERR_PTR(-EAGAIN)) + __i915_gem_userptr_set_active(obj, false); } - if (active) - __i915_gem_userptr_set_active(obj, true); + up_read(&mm->mmap_sem); if (IS_ERR(pages)) release_pages(pvec, pinned); -- 2.15.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx
