[PATCH 2/2] drm/i915/shrinker: Hook up vmap allocation failure notifier

[Chris Wilson <chris@chris-wilson.co.uk>]

If the core runs out of vmap address space, it will call a notifier in
case any driver can reap some of its vmaps. As i915.ko is possibily
holding onto vmap address space that could be recovered, hook into the
notifier chain and try and reap objects holding onto vmaps.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Roman Pen <r.peniaev@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/gpu/drm/i915/i915_drv.h          |  1 +
 drivers/gpu/drm/i915/i915_gem_shrinker.c | 39 ++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index b9989d05f82a..4646b8504b84 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1257,6 +1257,7 @@ struct i915_gem_mm {
 	struct i915_hw_ppgtt *aliasing_ppgtt;
 
 	struct notifier_block oom_notifier;
+	struct notifier_block vmap_notifier;
 	struct shrinker shrinker;
 	bool shrinker_no_lock_stealing;
 
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index d3c473ffb90a..54943f983dc4 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -28,6 +28,7 @@
 #include <linux/swap.h>
 #include <linux/pci.h>
 #include <linux/dma-buf.h>
+#include <linux/vmalloc.h>
 #include <drm/drmP.h>
 #include <drm/i915_drm.h>
 
@@ -356,6 +357,40 @@ i915_gem_shrinker_oom(struct notifier_block *nb, unsigned long event, void *ptr)
 	return NOTIFY_DONE;
 }
 
+static int
+i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr)
+{
+	struct drm_i915_private *dev_priv =
+		container_of(nb, struct drm_i915_private, mm.vmap_notifier);
+	struct drm_device *dev = dev_priv->dev;
+	unsigned long timeout = msecs_to_jiffies(5000) + 1;
+	unsigned long freed_pages;
+	bool was_interruptible;
+	bool unlock;
+
+	while (!i915_gem_shrinker_lock(dev, &unlock) && --timeout) {
+		schedule_timeout_killable(1);
+		if (fatal_signal_pending(current))
+			return NOTIFY_DONE;
+	}
+	if (timeout == 0) {
+		pr_err("Unable to purge GPU vmaps due to lock contention.\n");
+		return NOTIFY_DONE;
+	}
+
+	was_interruptible = dev_priv->mm.interruptible;
+	dev_priv->mm.interruptible = false;
+
+	freed_pages = i915_gem_shrink_all(dev_priv);
+
+	dev_priv->mm.interruptible = was_interruptible;
+	if (unlock)
+		mutex_unlock(&dev->struct_mutex);
+
+	*(unsigned long *)ptr += freed_pages;
+	return NOTIFY_DONE;
+}
+
 /**
  * i915_gem_shrinker_init - Initialize i915 shrinker
  * @dev_priv: i915 device
@@ -371,6 +406,9 @@ void i915_gem_shrinker_init(struct drm_i915_private *dev_priv)
 
 	dev_priv->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
 	WARN_ON(register_oom_notifier(&dev_priv->mm.oom_notifier));
+
+	dev_priv->mm.vmap_notifier.notifier_call = i915_gem_shrinker_vmap;
+	WARN_ON(register_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
 }
 
 /**
@@ -381,6 +419,7 @@ void i915_gem_shrinker_init(struct drm_i915_private *dev_priv)
  */
 void i915_gem_shrinker_cleanup(struct drm_i915_private *dev_priv)
 {
+	WARN_ON(unregister_vmap_purge_notifier(&dev_priv->mm.vmap_notifier));
 	WARN_ON(unregister_oom_notifier(&dev_priv->mm.oom_notifier));
 	unregister_shrinker(&dev_priv->mm.shrinker);
 }
-- 
2.8.0.rc3