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drm/i915: Remove livelock from "do_idle_maps" vtd w/a

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A call to wait for the GT to idle from inside the put_pages fallback is
prone to cause an uninterruptible livelock. As it does not provide
adequate serialisation with new requests, simply fallback to a trivial
sleep.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201209164008.5487-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2020-12-09 16:40:06 +00:00
parent 338d58cf47
commit 63de1da147
1 changed files with 9 additions and 14 deletions
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23
drivers/gpu/drm/i915/i915_gem_gtt.c
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@ -55,22 +55,17 @@ int i915_gem_gtt_prepare_pages(struct drm_i915_gem_object *obj,
void i915_gem_gtt_finish_pages(struct drm_i915_gem_object *obj,
struct sg_table *pages)
{
struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
struct device *kdev = &dev_priv->drm.pdev->dev;
struct i915_ggtt *ggtt = &dev_priv->ggtt;
struct drm_i915_private *i915 = to_i915(obj->base.dev);
struct i915_ggtt *ggtt = &i915->ggtt;
if (unlikely(ggtt->do_idle_maps)) {
/* XXX This does not prevent more requests being submitted! */
if (intel_gt_retire_requests_timeout(ggtt->vm.gt,
-MAX_SCHEDULE_TIMEOUT)) {
drm_err(&dev_priv->drm,
"Failed to wait for idle; VT'd may hang.\n");
/* Wait a bit, in hopes it avoids the hang */
udelay(10);
}
}
/* XXX This does not prevent more requests being submitted! */
if (unlikely(ggtt->do_idle_maps))
/* Wait a bit, in the hope it avoids the hang */
usleep_range(100, 250);
dma_unmap_sg(kdev, pages->sgl, pages->nents, PCI_DMA_BIDIRECTIONAL);
dma_unmap_sg(&i915->drm.pdev->dev,
pages->sgl, pages->nents,
PCI_DMA_BIDIRECTIONAL);
}
/**