Re: [Intel-gfx] [PATCH 04/21] drm/i915: Refresh the errno to vmf_fault translations

[Abdiel Janulgue]

On 02/09/2019 7.02, Chris Wilson wrote:
> It's been a long time since we accidentally reported -EIO upon wedging,
> it can now only be generated by failure to swap in a page.
> 

Reviewed-by: Abdiel Janulgue 

> Signed-off-by: Chris Wilson 
> Cc: Abdiel Janulgue 
> ---
>  drivers/gpu/drm/i915/gem/i915_gem_mman.c | 39 +---
>  1 file changed, 15 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c 
> b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> index 261c9bd83f51..82db2b783123 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> @@ -287,6 +287,9 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf)
>   view.type = I915_GGTT_VIEW_PARTIAL;
>   vma = i915_gem_object_ggtt_pin(obj, , 0, 0, flags);
>   }
> +
> + /* The entire mappable GGTT is pinned? Unexpected! */
> + GEM_BUG_ON(vma == ERR_PTR(-ENOSPC));
>   }
>   if (IS_ERR(vma)) {
>   ret = PTR_ERR(vma);
> @@ -333,23 +336,19 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf)
>   i915_gem_object_unpin_pages(obj);
>  err:
>   switch (ret) {
> - case -EIO:
> - /*
> -  * We eat errors when the gpu is terminally wedged to avoid
> -  * userspace unduly crashing (gl has no provisions for mmaps to
> -  * fail). But any other -EIO isn't ours (e.g. swap in failure)
> -  * and so needs to be reported.
> -  */
> - if (!intel_gt_is_wedged(ggtt->vm.gt))
> - return VM_FAULT_SIGBUS;
> - /* else, fall through */
> - case -EAGAIN:
> - /*
> -  * EAGAIN means the gpu is hung and we'll wait for the error
> -  * handler to reset everything when re-faulting in
> -  * i915_mutex_lock_interruptible.
> -  */
> + default:
> + WARN_ONCE(ret, "unhandled error in %s: %i\n", __func__, ret);
> + /* fallthrough */
> + case -EIO: /* shmemfs failure from swap device */
> + case -EFAULT: /* purged object */
> + return VM_FAULT_SIGBUS;
> +
> + case -ENOSPC: /* shmemfs allocation failure */
> + case -ENOMEM: /* our allocation failure */
> + return VM_FAULT_OOM;
> +
>   case 0:
> + case -EAGAIN:
>   case -ERESTARTSYS:
>   case -EINTR:
>   case -EBUSY:
> @@ -358,14 +357,6 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf)
>* already did the job.
>*/
>   return VM_FAULT_NOPAGE;
> - case -ENOMEM:
> - return VM_FAULT_OOM;
> - case -ENOSPC:
> - case -EFAULT:
> - return VM_FAULT_SIGBUS;
> - default:
> - WARN_ONCE(ret, "unhandled error in %s: %i\n", __func__, ret);
> - return VM_FAULT_SIGBUS;
>   }
>  }
>  
> 
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[Intel-gfx] [PATCH 04/21] drm/i915: Refresh the errno to vmf_fault translations

[Chris Wilson]

It's been a long time since we accidentally reported -EIO upon wedging,
it can now only be generated by failure to swap in a page.

Signed-off-by: Chris Wilson 
Cc: Abdiel Janulgue 
---
 drivers/gpu/drm/i915/gem/i915_gem_mman.c | 39 +---
 1 file changed, 15 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c 
b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index 261c9bd83f51..82db2b783123 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -287,6 +287,9 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf)
view.type = I915_GGTT_VIEW_PARTIAL;
vma = i915_gem_object_ggtt_pin(obj, , 0, 0, flags);
}
+
+   /* The entire mappable GGTT is pinned? Unexpected! */
+   GEM_BUG_ON(vma == ERR_PTR(-ENOSPC));
}
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
@@ -333,23 +336,19 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf)
i915_gem_object_unpin_pages(obj);
 err:
switch (ret) {
-   case -EIO:
-   /*
-* We eat errors when the gpu is terminally wedged to avoid
-* userspace unduly crashing (gl has no provisions for mmaps to
-* fail). But any other -EIO isn't ours (e.g. swap in failure)
-* and so needs to be reported.
-*/
-   if (!intel_gt_is_wedged(ggtt->vm.gt))
-   return VM_FAULT_SIGBUS;
-   /* else, fall through */
-   case -EAGAIN:
-   /*
-* EAGAIN means the gpu is hung and we'll wait for the error
-* handler to reset everything when re-faulting in
-* i915_mutex_lock_interruptible.
-*/
+   default:
+   WARN_ONCE(ret, "unhandled error in %s: %i\n", __func__, ret);
+   /* fallthrough */
+   case -EIO: /* shmemfs failure from swap device */
+   case -EFAULT: /* purged object */
+   return VM_FAULT_SIGBUS;
+
+   case -ENOSPC: /* shmemfs allocation failure */
+   case -ENOMEM: /* our allocation failure */
+   return VM_FAULT_OOM;
+
case 0:
+   case -EAGAIN:
case -ERESTARTSYS:
case -EINTR:
case -EBUSY:
@@ -358,14 +357,6 @@ vm_fault_t i915_gem_fault(struct vm_fault *vmf)
 * already did the job.
 */
return VM_FAULT_NOPAGE;
-   case -ENOMEM:
-   return VM_FAULT_OOM;
-   case -ENOSPC:
-   case -EFAULT:
-   return VM_FAULT_SIGBUS;
-   default:
-   WARN_ONCE(ret, "unhandled error in %s: %i\n", __func__, ret);
-   return VM_FAULT_SIGBUS;
}
 }
 
-- 
2.23.0

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