Patch "drm/i915: Store a permanent error in obj->mm.pages" has been added to the 4.10-stable tree

This is a note to let you know that I've just added the patch titled

    drm/i915: Store a permanent error in obj->mm.pages

to the 4.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
drm-i915-store-a-permanent-error-in-obj-mm.pages.patch
and it can be found in the queue-4.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Chris Wilson <[email protected]>
Date: Tue, 7 Mar 2017 13:20:31 +0000
Subject: drm/i915: Store a permanent error in obj->mm.pages

From: Chris Wilson <[email protected]>

commit 0d9dc306e15b59bf50db87ebcb1e2248586d4733 upstream.

Once the object has been truncated, it is unrecoverable. To facilitate detection of this state store the error in obj->mm.pages.

This is required for the next patch which should be applied to v4.10 (via stable), so we also need to mark this patch for backporting. In that regard, let's consider this to be a fix/improvement too.

v2: Avoid dereferencing the ERR_PTR when freeing the object.

---
 drivers/gpu/drm/i915/i915_gem.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

@@ -2184,6 +2184,7 @@ i915_gem_object_truncate(struct drm_i915
 	 */
 	shmem_truncate_range(file_inode(obj->base.filp), 0, (loff_t)-1);
 	obj->mm.madv = __I915_MADV_PURGED;
+	obj->mm.pages = ERR_PTR(-EFAULT);
 }
 
 /* Try to discard unwanted pages */

@@ -2283,7 +2284,9 @@ void __i915_gem_object_put_pages(struct
 
 	__i915_gem_object_reset_page_iter(obj);
 
-	obj->ops->put_pages(obj, pages);
+	if (!IS_ERR(pages))
+		obj->ops->put_pages(obj, pages);
+
 unlock:
 	mutex_unlock(&obj->mm.lock);
 }

@@ -2501,7 +2504,7 @@ int __i915_gem_object_get_pages(struct d
 	if (err)
 		return err;
 
-	if (unlikely(!obj->mm.pages)) {
+	if (unlikely(IS_ERR_OR_NULL(obj->mm.pages))) {
 		err = ____i915_gem_object_get_pages(obj);
 		if (err)
 			goto unlock;

@@ -2579,7 +2582,7 @@ void *i915_gem_object_pin_map(struct drm
 
 	pinned = true;
 	if (!atomic_inc_not_zero(&obj->mm.pages_pin_count)) {
-		if (unlikely(!obj->mm.pages)) {
+		if (unlikely(IS_ERR_OR_NULL(obj->mm.pages))) {
 			ret = ____i915_gem_object_get_pages(obj);
 			if (ret)
 				goto err_unlock;

Patches currently in stable-queue which might be from [email protected] are

queue-4.10/drm-i915-squelch-any-ktime-jiffie-rounding-errors-for-wait-ioctl.patch queue-4.10/drm-i915-fbdev-stop-repeating-tile-configuration-on-stagnation.patch queue-4.10/drm-i915-store-a-permanent-error-in-obj-mm.pages.patch queue-4.10/drm-i915-gen9-increase-pcode-request-timeout-to-50ms.patch queue-4.10/drm-i915-avoid-tweaking-evaluation-thresholds-on-baytrail-v3.patch queue-4.10/drm-i915-fix-forcewake-active-domain-tracking.patch