Hi

Am 15.01.21 um 15:11 schrieb Daniel Vetter:

On Fri, Jan 15, 2021 at 09:57:24AM +0000, Kieran Bingham wrote:

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Hi Thomas,

On 15/01/2021 09:30, Thomas Zimmermann wrote:

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The GEM mmap code relies on the GEM object's mmap callback to set the VMA's vm_ops field. This is easily forgotten and already led to a memory leak in the CMA helpers. Instead set the vm_ops field in the DRM core code to the GEM object's value. Drivers with different needs can override this in their mmap callback.

v2:

• support (vm_ops == NULL) if mmap is given; required by VRAM helpers

I guess vram helpers need this because ttm has it's own vm_ops struct? Might be another thing worth unifying (eventually).

I've been working on converting drivers to struct drm_gem_object_funcs.mmap and using DRM helpers for the other mmap callbacks. Part of this would include some unifying of the vm_ops handling. TTM drivers are kind of special here.

Best regards Thomas

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Signed-off-by: Thomas Zimmermann tzimmermann@suse.de Fixes: f5ca8eb6f9bd ("drm/cma-helper: Implement mmap as GEM CMA object functions") Reported-by: Kieran Bingham kieran.bingham+renesas@ideasonboard.com Tested-by: Kieran Bingham kieran.bingham+renesas@ideasonboard.com

Re-tested just fine this side ;-)

• https://paste.ubuntu.com/p/Jgz6xMKNJX/

Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch

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Thanks

Kieran

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Cc: Maxime Ripard mripard@kernel.org Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: David Airlie airlied@linux.ie Cc: Daniel Vetter daniel@ffwll.ch Cc: Eric Anholt eric@anholt.net Cc: dri-devel@lists.freedesktop.org

---

drivers/gpu/drm/drm_gem.c | 19 ++++++++++--------- drivers/gpu/drm/drm_prime.c | 2 ++ 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index 34b2f111c01c..c2ce78c4edc3 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -1068,20 +1068,17 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size, drm_gem_object_get(obj);

vma->vm_private_data = obj;

• vma->vm_ops = obj->funcs->vm_ops;

  if (obj->funcs->mmap) { ret = obj->funcs->mmap(obj, vma);

• if (ret) {
  

• 	drm_gem_object_put(obj);
  

• 	return ret;
  

• }
  

• if (ret)
  

• 	goto err_drm_gem_object_put;
  

  WARN_ON(!(vma->vm_flags & VM_DONTEXPAND)); } else {

• if (obj->funcs->vm_ops)
  

• 	vma->vm_ops = obj->funcs->vm_ops;
  

• else {
  

• 	drm_gem_object_put(obj);
  

• 	return -EINVAL;
  

• if (!vma->vm_ops) {
  

• 	ret = -EINVAL;
  

• 	goto err_drm_gem_object_put;
  

  }

  vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;

@@ -1090,6 +1087,10 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size, }

return 0;

+err_drm_gem_object_put:

• drm_gem_object_put(obj);
• return ret; } EXPORT_SYMBOL(drm_gem_mmap_obj);

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 683aa29ecd3b..2a54f86856af 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -717,6 +717,8 @@ int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);

if (obj->funcs && obj->funcs->mmap) {

• vma->vm_ops = obj->funcs->vm_ops;
  

Do you know how much we still need the non-obj->funcs path here? Maybe time to detele it and wrape the obj->funcs check in a WARN_ON? -Daniel

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ret = obj->funcs->mmap(obj, vma);
if (ret)
	return ret;