[PATCH 2/2] drm/cma-helper: Implement mmap as GEM CMA object functions
Thomas Zimmermann
tzimmermann at suse.de
Thu Jan 14 15:15:30 UTC 2021
Hi
Am 14.01.21 um 15:34 schrieb Kieran Bingham:
> Hi Thomas,
>
> On 14/01/2021 13:26, Thomas Zimmermann wrote:
>> Hi Kieran
>>
>> Am 14.01.21 um 13:51 schrieb Kieran Bingham:
>>> Hi Thomas,
>>>
>>> On 23/11/2020 11:56, Thomas Zimmermann wrote:
>>>> The new GEM object function drm_gem_cma_mmap() sets the VMA flags
>>>> and offset as in the old implementation and immediately maps in the
>>>> buffer's memory pages.
>>>>
>>>> Changing CMA helpers to use the GEM object function allows for the
>>>> removal of the special implementations for mmap and gem_prime_mmap
>>>> callbacks. The regular functions drm_gem_mmap() and drm_gem_prime_mmap()
>>>> are now used.
>>>
>>> I've encountered a memory leak regression in our Renesas R-Car DU tests,
>>> and git bisection has led me to this patch (as commit f5ca8eb6f9).
>>>
>>> Running the tests sequentially, while grepping /proc/meminfo for Cma, it
>>> is evident that CMA memory is not released, until exhausted and the
>>> allocations fail (seen in [0]) shown by the error report:
>>>
>>>> self.fbs.append(pykms.DumbFramebuffer(self.card, mode.hdisplay,
>>>> mode.vdisplay, "XR24"))
>>>> ValueError: DRM_IOCTL_MODE_CREATE_DUMB failed: Cannot allocate memory
>>>
>>>
>>> Failing tests at f5ca8eb6f9 can be seen at [0], while the tests pass
>>> successfully [1] on the commit previous to that (bc2532ab7c2):
>>>
>>> Reverting f5ca8eb6f9 also produces a successful pass [2]
>>>
>>> [0] https://paste.ubuntu.com/p/VjPGPgswxR/ # Failed at f5ca8eb6f9
>>> [1] https://paste.ubuntu.com/p/78RRp2WpNR/ # Success at bc2532ab7c2
>>> [2] https://paste.ubuntu.com/p/qJKjZZN2pt/ # Success with revert
>>>
>>>
>>> I don't believe we handle mmap specially in the RCar-DU driver, so I
>>> wonder if this issue has hit anyone else as well?
>>>
>>> Any ideas of a repair without a revert ? Or do we just need to submit a
>>> revert?
>>
>> I think we might not be setting the VMA ops and therefore not finalize
>> the BO correctly. Could you please apply the attched (quick-and-dirty)
>> patch and try again?
>
> Thanks for the quick response.
>
> I can confirm the quick-and-dirty patch resolves the issue:
> https://paste.ubuntu.com/p/sKDp3dNvwV/
>
> You can add a
> Tested-by: Kieran Bingham <kieran.bingham+renesas at ideasonboard.com>
Great! If you don't mind, I'd also add you in the Reported-by tag.
>
> if it stays like that, but I suspect there might be a better place to
> initialise the ops rather than in the mmap call itself.
I think that's the fix, basically. We could put such a line as a
fall-back somewhere into the DRM core code. But I don't know if this
really works with all drivers. Maybe there's one that requires vm_ops to
be NULL.
Thanks for reporting this issue and testing quickly.
Best regards
Thomas
>
> Happy to do further testing as required.
>
> --
> Regards
>
> Kieran
>
>
>> Best regards
>> Thomas
>>
>>>
>>> I've yet to fully understand the implications of the patch below.
>>>
>>> Thanks
>>> --
>>> Regards
>>>
>>> Kieran
>>>
>>>
>>>
>>>> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
>>>> ---
>>>> drivers/gpu/drm/drm_file.c | 3 +-
>>>> drivers/gpu/drm/drm_gem_cma_helper.c | 121 +++++++++------------------
>>>> drivers/gpu/drm/pl111/pl111_drv.c | 2 +-
>>>> drivers/gpu/drm/vc4/vc4_bo.c | 2 +-
>>>> include/drm/drm_gem_cma_helper.h | 10 +--
>>>> 5 files changed, 44 insertions(+), 94 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
>>>> index b50380fa80ce..80886d50d0f1 100644
>>>> --- a/drivers/gpu/drm/drm_file.c
>>>> +++ b/drivers/gpu/drm/drm_file.c
>>>> @@ -113,8 +113,7 @@ bool drm_dev_needs_global_mutex(struct drm_device
>>>> *dev)
>>>> * The memory mapping implementation will vary depending on how the
>>>> driver
>>>> * manages memory. Legacy drivers will use the deprecated
>>>> drm_legacy_mmap()
>>>> * function, modern drivers should use one of the provided
>>>> memory-manager
>>>> - * specific implementations. For GEM-based drivers this is
>>>> drm_gem_mmap(), and
>>>> - * for drivers which use the CMA GEM helpers it's drm_gem_cma_mmap().
>>>> + * specific implementations. For GEM-based drivers this is
>>>> drm_gem_mmap().
>>>> *
>>>> * No other file operations are supported by the DRM userspace API.
>>>> Overall the
>>>> * following is an example &file_operations structure::
>>>> diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c
>>>> b/drivers/gpu/drm/drm_gem_cma_helper.c
>>>> index 6a4ef335ebc9..7942cf05cd93 100644
>>>> --- a/drivers/gpu/drm/drm_gem_cma_helper.c
>>>> +++ b/drivers/gpu/drm/drm_gem_cma_helper.c
>>>> @@ -38,6 +38,7 @@ static const struct drm_gem_object_funcs
>>>> drm_gem_cma_default_funcs = {
>>>> .print_info = drm_gem_cma_print_info,
>>>> .get_sg_table = drm_gem_cma_get_sg_table,
>>>> .vmap = drm_gem_cma_vmap,
>>>> + .mmap = drm_gem_cma_mmap,
>>>> .vm_ops = &drm_gem_cma_vm_ops,
>>>> };
>>>> @@ -277,62 +278,6 @@ const struct vm_operations_struct
>>>> drm_gem_cma_vm_ops = {
>>>> };
>>>> EXPORT_SYMBOL_GPL(drm_gem_cma_vm_ops);
>>>> -static int drm_gem_cma_mmap_obj(struct drm_gem_cma_object *cma_obj,
>>>> - struct vm_area_struct *vma)
>>>> -{
>>>> - int ret;
>>>> -
>>>> - /*
>>>> - * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and
>>>> set the
>>>> - * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we
>>>> want to map
>>>> - * the whole buffer.
>>>> - */
>>>> - vma->vm_flags &= ~VM_PFNMAP;
>>>> - vma->vm_pgoff = 0;
>>>> -
>>>> - ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
>>>> - cma_obj->paddr, vma->vm_end - vma->vm_start);
>>>> - if (ret)
>>>> - drm_gem_vm_close(vma);
>>>> -
>>>> - return ret;
>>>> -}
>>>> -
>>>> -/**
>>>> - * drm_gem_cma_mmap - memory-map a CMA GEM object
>>>> - * @filp: file object
>>>> - * @vma: VMA for the area to be mapped
>>>> - *
>>>> - * This function implements an augmented version of the GEM DRM file
>>>> mmap
>>>> - * operation for CMA objects: In addition to the usual GEM VMA setup it
>>>> - * immediately faults in the entire object instead of using on-demaind
>>>> - * faulting. Drivers which employ the CMA helpers should use this
>>>> function
>>>> - * as their ->mmap() handler in the DRM device file's file_operations
>>>> - * structure.
>>>> - *
>>>> - * Instead of directly referencing this function, drivers should use
>>>> the
>>>> - * DEFINE_DRM_GEM_CMA_FOPS().macro.
>>>> - *
>>>> - * Returns:
>>>> - * 0 on success or a negative error code on failure.
>>>> - */
>>>> -int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma)
>>>> -{
>>>> - struct drm_gem_cma_object *cma_obj;
>>>> - struct drm_gem_object *gem_obj;
>>>> - int ret;
>>>> -
>>>> - ret = drm_gem_mmap(filp, vma);
>>>> - if (ret)
>>>> - return ret;
>>>> -
>>>> - gem_obj = vma->vm_private_data;
>>>> - cma_obj = to_drm_gem_cma_obj(gem_obj);
>>>> -
>>>> - return drm_gem_cma_mmap_obj(cma_obj, vma);
>>>> -}
>>>> -EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
>>>> -
>>>> #ifndef CONFIG_MMU
>>>> /**
>>>> * drm_gem_cma_get_unmapped_area - propose address for mapping in
>>>> noMMU cases
>>>> @@ -500,33 +445,6 @@ drm_gem_cma_prime_import_sg_table(struct
>>>> drm_device *dev,
>>>> }
>>>> EXPORT_SYMBOL_GPL(drm_gem_cma_prime_import_sg_table);
>>>> -/**
>>>> - * drm_gem_cma_prime_mmap - memory-map an exported CMA GEM object
>>>> - * @obj: GEM object
>>>> - * @vma: VMA for the area to be mapped
>>>> - *
>>>> - * This function maps a buffer imported via DRM PRIME into a userspace
>>>> - * process's address space. Drivers that use the CMA helpers should
>>>> set this
>>>> - * as their &drm_driver.gem_prime_mmap callback.
>>>> - *
>>>> - * Returns:
>>>> - * 0 on success or a negative error code on failure.
>>>> - */
>>>> -int drm_gem_cma_prime_mmap(struct drm_gem_object *obj,
>>>> - struct vm_area_struct *vma)
>>>> -{
>>>> - struct drm_gem_cma_object *cma_obj;
>>>> - int ret;
>>>> -
>>>> - ret = drm_gem_mmap_obj(obj, obj->size, vma);
>>>> - if (ret < 0)
>>>> - return ret;
>>>> -
>>>> - cma_obj = to_drm_gem_cma_obj(obj);
>>>> - return drm_gem_cma_mmap_obj(cma_obj, vma);
>>>> -}
>>>> -EXPORT_SYMBOL_GPL(drm_gem_cma_prime_mmap);
>>>> -
>>>> /**
>>>> * drm_gem_cma_vmap - map a CMA GEM object into the kernel's virtual
>>>> * address space
>>>> @@ -553,6 +471,43 @@ int drm_gem_cma_vmap(struct drm_gem_object *obj,
>>>> struct dma_buf_map *map)
>>>> }
>>>> EXPORT_SYMBOL_GPL(drm_gem_cma_vmap);
>>>> +/**
>>>> + * drm_gem_cma_mmap - memory-map an exported CMA GEM object
>>>> + * @obj: GEM object
>>>> + * @vma: VMA for the area to be mapped
>>>> + *
>>>> + * This function maps a buffer into a userspace process's address
>>>> space.
>>>> + * In addition to the usual GEM VMA setup it immediately faults in
>>>> the entire
>>>> + * object instead of using on-demand faulting. Drivers that use the CMA
>>>> + * helpers should set this as their &drm_gem_object_funcs.mmap
>>>> callback.
>>>> + *
>>>> + * Returns:
>>>> + * 0 on success or a negative error code on failure.
>>>> + */
>>>> +int drm_gem_cma_mmap(struct drm_gem_object *obj, struct
>>>> vm_area_struct *vma)
>>>> +{
>>>> + struct drm_gem_cma_object *cma_obj;
>>>> + int ret;
>>>> +
>>>> + /*
>>>> + * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and
>>>> set the
>>>> + * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we
>>>> want to map
>>>> + * the whole buffer.
>>>> + */
>>>> + vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
>>>> + vma->vm_flags &= ~VM_PFNMAP;
>>>> +
>>>> + cma_obj = to_drm_gem_cma_obj(obj);
>>>> +
>>>> + ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr,
>>>> + cma_obj->paddr, vma->vm_end - vma->vm_start);
>>>> + if (ret)
>>>> + drm_gem_vm_close(vma);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(drm_gem_cma_mmap);
>>>> +
>>>> /**
>>>> * drm_gem_cma_prime_import_sg_table_vmap - PRIME import another
>>>> driver's
>>>> * scatter/gather table and get the virtual address of the buffer
>>>> diff --git a/drivers/gpu/drm/pl111/pl111_drv.c
>>>> b/drivers/gpu/drm/pl111/pl111_drv.c
>>>> index 40e6708fbbe2..e4dcaef6c143 100644
>>>> --- a/drivers/gpu/drm/pl111/pl111_drv.c
>>>> +++ b/drivers/gpu/drm/pl111/pl111_drv.c
>>>> @@ -228,7 +228,7 @@ static const struct drm_driver pl111_drm_driver = {
>>>> .prime_handle_to_fd = drm_gem_prime_handle_to_fd,
>>>> .prime_fd_to_handle = drm_gem_prime_fd_to_handle,
>>>> .gem_prime_import_sg_table = pl111_gem_import_sg_table,
>>>> - .gem_prime_mmap = drm_gem_cma_prime_mmap,
>>>> + .gem_prime_mmap = drm_gem_prime_mmap,
>>>> #if defined(CONFIG_DEBUG_FS)
>>>> .debugfs_init = pl111_debugfs_init,
>>>> diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
>>>> index 813e6cb3f9af..dc316cb79e00 100644
>>>> --- a/drivers/gpu/drm/vc4/vc4_bo.c
>>>> +++ b/drivers/gpu/drm/vc4/vc4_bo.c
>>>> @@ -782,7 +782,7 @@ int vc4_prime_mmap(struct drm_gem_object *obj,
>>>> struct vm_area_struct *vma)
>>>> return -EINVAL;
>>>> }
>>>> - return drm_gem_cma_prime_mmap(obj, vma);
>>>> + return drm_gem_prime_mmap(obj, vma);
>>>> }
>>>> int vc4_prime_vmap(struct drm_gem_object *obj, struct dma_buf_map
>>>> *map)
>>>> diff --git a/include/drm/drm_gem_cma_helper.h
>>>> b/include/drm/drm_gem_cma_helper.h
>>>> index 4680275ab339..0a9711caa3e8 100644
>>>> --- a/include/drm/drm_gem_cma_helper.h
>>>> +++ b/include/drm/drm_gem_cma_helper.h
>>>> @@ -59,7 +59,7 @@ struct drm_gem_cma_object {
>>>> .poll = drm_poll,\
>>>> .read = drm_read,\
>>>> .llseek = noop_llseek,\
>>>> - .mmap = drm_gem_cma_mmap,\
>>>> + .mmap = drm_gem_mmap,\
>>>> DRM_GEM_CMA_UNMAPPED_AREA_FOPS \
>>>> }
>>>> @@ -76,9 +76,6 @@ int drm_gem_cma_dumb_create(struct drm_file
>>>> *file_priv,
>>>> struct drm_device *drm,
>>>> struct drm_mode_create_dumb *args);
>>>> -/* set vm_flags and we can change the VM attribute to other one at
>>>> here */
>>>> -int drm_gem_cma_mmap(struct file *filp, struct vm_area_struct *vma);
>>>> -
>>>> /* allocate physical memory */
>>>> struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm,
>>>> size_t size);
>>>> @@ -101,9 +98,8 @@ struct drm_gem_object *
>>>> drm_gem_cma_prime_import_sg_table(struct drm_device *dev,
>>>> struct dma_buf_attachment *attach,
>>>> struct sg_table *sgt);
>>>> -int drm_gem_cma_prime_mmap(struct drm_gem_object *obj,
>>>> - struct vm_area_struct *vma);
>>>> int drm_gem_cma_vmap(struct drm_gem_object *obj, struct dma_buf_map
>>>> *map);
>>>> +int drm_gem_cma_mmap(struct drm_gem_object *obj, struct
>>>> vm_area_struct *vma);
>>>> /**
>>>> * DRM_GEM_CMA_DRIVER_OPS_WITH_DUMB_CREATE - CMA GEM driver operations
>>>> @@ -123,7 +119,7 @@ int drm_gem_cma_vmap(struct drm_gem_object *obj,
>>>> struct dma_buf_map *map);
>>>> .prime_handle_to_fd = drm_gem_prime_handle_to_fd, \
>>>> .prime_fd_to_handle = drm_gem_prime_fd_to_handle, \
>>>> .gem_prime_import_sg_table = drm_gem_cma_prime_import_sg_table, \
>>>> - .gem_prime_mmap = drm_gem_cma_prime_mmap
>>>> + .gem_prime_mmap = drm_gem_prime_mmap
>>>> /**
>>>> * DRM_GEM_CMA_DRIVER_OPS - CMA GEM driver operations
>>>>
>>>
>>> _______________________________________________
>>> dri-devel mailing list
>>> dri-devel at lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>>
>>
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer
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