5 files changed, 17 insertions, 9 deletions

diff --git a/drivers/gpu/drm/ttm/ttm_agp_backend.c b/drivers/gpu/drm/ttm/ttm_agp_backend.c
index 3302f99e7497..764be36397fd 100644
--- a/drivers/gpu/drm/ttm/ttm_agp_backend.c
+++ b/drivers/gpu/drm/ttm/ttm_agp_backend.c
@@ -126,6 +126,7 @@ struct ttm_tt *ttm_agp_tt_create(struct ttm_bo_device *bdev,
         agp_be->ttm.func = &ttm_agp_func;
 
         if (ttm_tt_init(&agp_be->ttm, bdev, size, page_flags, dummy_read_page)) {
+                kfree(agp_be);
                 return NULL;
         }
 
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index a06651309388..214b7992a3aa 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -351,9 +351,11 @@ static int ttm_bo_handle_move_mem(struct ttm_buffer_object *bo,
 
 moved:
         if (bo->evicted) {
-                ret = bdev->driver->invalidate_caches(bdev, bo->mem.placement);
-                if (ret)
-                        pr_err("Can not flush read caches\n");
+                if (bdev->driver->invalidate_caches) {
+                        ret = bdev->driver->invalidate_caches(bdev, bo->mem.placement);
+                        if (ret)
+                                pr_err("Can not flush read caches\n");
+                }
                 bo->evicted = false;
         }
 
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index 801231c9ae48..0ce48e5a9cb4 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -339,11 +339,13 @@ int ttm_bo_mmap(struct file *filp, struct vm_area_struct *vma,
         vma->vm_private_data = bo;
 
         /*
-         * PFNMAP is faster than MIXEDMAP due to reduced page
-         * administration. So use MIXEDMAP only if private VMA, where
-         * we need to support COW.
+         * We'd like to use VM_PFNMAP on shared mappings, where
+         * (vma->vm_flags & VM_SHARED) != 0, for performance reasons,
+         * but for some reason VM_PFNMAP + x86 PAT + write-combine is very
+         * bad for performance. Until that has been sorted out, use
+         * VM_MIXEDMAP on all mappings. See freedesktop.org bug #75719
          */
-        vma->vm_flags |= (vma->vm_flags & VM_SHARED) ? VM_PFNMAP : VM_MIXEDMAP;
+        vma->vm_flags |= VM_MIXEDMAP;
         vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
         return 0;
 out_unref:
@@ -359,7 +361,7 @@ int ttm_fbdev_mmap(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
 
         vma->vm_ops = &ttm_bo_vm_ops;
         vma->vm_private_data = ttm_bo_reference(bo);
-        vma->vm_flags |= (vma->vm_flags & VM_SHARED) ? VM_PFNMAP : VM_MIXEDMAP;
+        vma->vm_flags |= VM_MIXEDMAP;
         vma->vm_flags |= VM_IO | VM_DONTEXPAND;
         return 0;
 }
diff --git a/drivers/gpu/drm/ttm/ttm_object.c b/drivers/gpu/drm/ttm/ttm_object.c
index 37079859afc8..53b51c4e671a 100644
--- a/drivers/gpu/drm/ttm/ttm_object.c
+++ b/drivers/gpu/drm/ttm/ttm_object.c
@@ -292,7 +292,7 @@ int ttm_ref_object_add(struct ttm_object_file *tfile,
 
                 if (ret == 0) {
                         ref = drm_hash_entry(hash, struct ttm_ref_object, hash);
-                        if (!kref_get_unless_zero(&ref->kref)) {
+                        if (kref_get_unless_zero(&ref->kref)) {
                                 rcu_read_unlock();
                                 break;
                         }
diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
index 9af99084b344..75f319090043 100644
--- a/drivers/gpu/drm/ttm/ttm_tt.c
+++ b/drivers/gpu/drm/ttm/ttm_tt.c
@@ -380,6 +380,9 @@ static void ttm_tt_clear_mapping(struct ttm_tt *ttm)
         pgoff_t i;
         struct page **page = ttm->pages;
 
+        if (ttm->page_flags & TTM_PAGE_FLAG_SG)
+                return;
+
         for (i = 0; i < ttm->num_pages; ++i) {
                 (*page)->mapping = NULL;
                 (*page++)->index = 0;