[Intel-gfx] [PATCH] drm/i915: Unregister the i915_gem_inactive_shrink on module load failure

[Keith Packard]

On Sun, 10 Jul 2011 17:32:42 +0100, Chris Wilson <chris at chris-wilson.co.uk> wrote:

> Otherwise, the core vm will call into an non-existent code page. Oops.

There are more problems than this in the load failure path; I posted a
longer patch a while ago:

From 138df88a83f36e3ba8709d7a8a88d3b536dbc70b Mon Sep 17 00:00:00 2001
From: Keith Packard <keithp at keithp.com>
Date: Sun, 10 Jul 2011 13:12:17 -0700
Subject: [PATCH] drm/i915: Clean up i915_driver_load failure path

i915_driver_load adds a write-combining MTRR region for the GTT
aperture to improve memory speeds through the aperture. If
i915_driver_load fails after this, it would not have cleaned up the
MTRR. This shouldn't cause any problems, except for consuming an MTRR
register. Still, it's best to clean up completely in the failure path,
which is easily done by calling mtrr_del if the mtrr was successfully
allocated.

i915_driver_load calls i915_gem_load which register
i915_gem_inactive_shrink. If i915_driver_load fails after calling
i915_gem_load, the shrinker will be left registered. When called, it
will access freed memory and crash. The fix is to unregister the shrinker in the
failure path using code duplicated from i915_driver_unload.

After failing to initialize the GTT (which cannot happen, btw,
intel_gtt_get returns a fixed (non-NULL) value), it tries to free the
uninitialized WC IO mapping. Fixed this by changing the target from
out_iomapfree to out_rmmap

Signed-off-by: Keith Packard <keithp at keithp.com>
---
 drivers/gpu/drm/i915/i915_dma.c |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index e178702..296fbd6 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1943,7 +1943,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 	if (!dev_priv->mm.gtt) {
 		DRM_ERROR("Failed to initialize GTT\n");
 		ret = -ENODEV;
-		goto out_iomapfree;
+		goto out_rmmap;
 	}
 
 	agp_size = dev_priv->mm.gtt->gtt_mappable_entries << PAGE_SHIFT;
@@ -1987,7 +1987,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 	if (dev_priv->wq == NULL) {
 		DRM_ERROR("Failed to create our workqueue.\n");
 		ret = -ENOMEM;
-		goto out_iomapfree;
+		goto out_mtrrfree;
 	}
 
 	/* enable GEM by default */
@@ -2074,13 +2074,21 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
 	return 0;
 
 out_gem_unload:
+	if (dev_priv->mm.inactive_shrinker.shrink)
+		unregister_shrinker(&dev_priv->mm.inactive_shrinker);
+
 	if (dev->pdev->msi_enabled)
 		pci_disable_msi(dev->pdev);
 
 	intel_teardown_gmbus(dev);
 	intel_teardown_mchbar(dev);
 	destroy_workqueue(dev_priv->wq);
-out_iomapfree:
+out_mtrrfree:
+	if (dev_priv->mm.gtt_mtrr >= 0) {
+		mtrr_del(dev_priv->mm.gtt_mtrr, dev->agp->base,
+			 dev->agp->agp_info.aper_size * 1024 * 1024);
+		dev_priv->mm.gtt_mtrr = -1;
+	}
 	io_mapping_free(dev_priv->mm.gtt_mapping);
 out_rmmap:
 	pci_iounmap(dev->pdev, dev_priv->regs);
-- 
1.7.5.4


-- 
keith.packard at intel.com
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