[PATCH 2/3] drm/amdkfd: refine the gfx BO based dmabuf handling
Lang Yu
Lang.Yu at amd.com
Tue Jul 26 02:18:18 UTC 2022
On 07/25/ , Felix Kuehling wrote:
> Am 2022-07-25 um 20:40 schrieb Lang Yu:
> > On 07/25/ , Felix Kuehling wrote:
> > > Am 2022-07-25 um 20:15 schrieb Lang Yu:
> > > > On 07/25/ , Felix Kuehling wrote:
> > > > > Am 2022-07-25 um 06:32 schrieb Lang Yu:
> > > > > > We have memory leak issue in current implenmention, i.e.,
> > > > > > the allocated struct kgd_mem memory is not handled properly.
> > > > > >
> > > > > > The idea is always creating a buffer object when importing
> > > > > > a gfx BO based dmabuf.
> > > > > >
> > > > > > Signed-off-by: Lang Yu <Lang.Yu at amd.com>
> > > > > > ---
> > > > > > .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 99 +++++++++++++------
> > > > > > 1 file changed, 70 insertions(+), 29 deletions(-)
> > > > > >
> > > > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > > > > > index b3806ebe5ef7..c1855b72a3f0 100644
> > > > > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > > > > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> > > > > > @@ -225,7 +225,8 @@ void amdgpu_amdkfd_release_notify(struct amdgpu_bo *bo)
> > > > > > u32 alloc_flags = bo->kfd_bo->alloc_flags;
> > > > > > u64 size = amdgpu_bo_size(bo);
> > > > > > - unreserve_mem_limit(adev, size, alloc_flags);
> > > > > > + if (!bo->kfd_bo->is_imported)
> > > > > > + unreserve_mem_limit(adev, size, alloc_flags);
> > > > > > kfree(bo->kfd_bo);
> > > > > > }
> > > > > > @@ -784,6 +785,24 @@ kfd_mem_dmaunmap_attachment(struct kgd_mem *mem,
> > > > > > }
> > > > > > }
> > > > > > +static struct drm_gem_object*
> > > > > > +amdgpu_amdkfd_import(struct drm_device *dev, struct dma_buf *dma_buf)
> > > > > > +{
> > > > > > + struct drm_gem_object *gobj;
> > > > > > + struct amdgpu_bo *abo;
> > > > > > +
> > > > > > + if (dma_buf->ops == &amdgpu_dmabuf_ops) {
> > > > > I'd rather remove this limitation. We should be able to use any DMABuf with
> > > > > KFD. This check was added when we basically sidestepped all the dmabuf
> > > > > attachment code and just extracted the amdgpu_bo ourselves. I don't think we
> > > > > want to keep doing that.
> > > > This limitation here is to just reference the gobj if it is an amdgpu bo
> > > > and from same device instead of creating a gobj when importing a dmabuf.
> > > >
> > > > > Please see my patch "[PATCH v2 1/2] drm/amdgpu: Generalize KFD dmabuf
> > > > > import" sent to amd-gfx on March 16. I'm about to send an updated version of
> > > > > this as part of upstream RDMA support soon.
> > > > The "drm/amdgpu: Generalize KFD dmabuf import" doesn't handle the struct kgd_mem
> > > > memory leak issue. Looking forward to the updated version. Thanks!
> > > Maybe we're trying to fix different problems. Can you give a more detailed
> > > explanation of the memory leak you're seeing? It's not obvious to me.
> > The struct kgd_mem is allocted by "*mem = kzalloc(sizeof(struct kgd_mem), GFP_KERNEL);",
> > but it is not assigned to bo->kfd_bo like this "bo->kfd_bo = *mem;". Then *mem will
> > never be freed.
>
> True. With the current upstream driver there is no way this can happen,
> because we don't have an API for KFD to export a dmabuf in a way that could
> later be imported. But with the RDMA and IPC features we're working on, this
> becomes a real possibility.
>
> Your solution is to ensure that the dmabuf import always creates a new
> amdgpu_bo. But that can add a lot of overhead. How about this idea: In
> amdgpu_amdkfd_gpuvm_free_memory_of_gpu we could add this after
> drm_gem_object_put:
>
> if (mem->bo->kfd_bo != mem)
> kfree(mem);
This way will turn a imported BO(e.g., a gfx BO) to a kfd BO , i.e.,
assign *mem to bo->kfd_bo. I'm not sure whether it makes sense
to modify the original BO like this.
The overhead is drm_prime_pages_to_sg + dma_map_sgtable when importing a
gfx dmabuf from same device.
Regards,
Lang
> That way amdgpu_amdkfd_release_notify would only be responsible for freeing
> the original kgd_mem. Any imports will be freed explicitly.
>
> Regards,
> Felix
>
>
> >
> > Regards,
> > Lang
> >
> > > The problem I'm trying to solve is, to ensure that each exported BO only has
> > > a single dmabuf because we run into problems with GEM if we have multiple
> > > dmabufs pointing to the same GEM object. That also enables re-exporting
> > > dmabufs of imported BOs. At the same time I'm removing any limitations of
> > > the types of BOs we can import, and trying to eliminate any custom dmabuf
> > > handling in KFD.
> > >
> > > Regards,
> > > Felix
> > >
> > >
> > > > Regards,
> > > > Lang
> > > >
> > > > > Regards,
> > > > > Felix
> > > > >
> > > > >
> > > > > > + gobj = dma_buf->priv;
> > > > > > + abo = gem_to_amdgpu_bo(gobj);
> > > > > > + if (gobj->dev == dev && abo->kfd_bo) {
> > > > > > + drm_gem_object_get(gobj);
> > > > > > + return gobj;
> > > > > > + }
> > > > > > + }
> > > > > > +
> > > > > > + return amdgpu_dma_buf_create_obj_and_attach(dev, dma_buf);
> > > > > > +}
> > > > > > +
> > > > > > static int
> > > > > > kfd_mem_attach_dmabuf(struct amdgpu_device *adev, struct kgd_mem *mem,
> > > > > > struct amdgpu_bo **bo)
> > > > > > @@ -802,7 +821,7 @@ kfd_mem_attach_dmabuf(struct amdgpu_device *adev, struct kgd_mem *mem,
> > > > > > }
> > > > > > }
> > > > > > - gobj = amdgpu_gem_prime_import(adev_to_drm(adev), mem->dmabuf);
> > > > > > + gobj = amdgpu_amdkfd_import(adev_to_drm(adev), mem->dmabuf);
> > > > > > if (IS_ERR(gobj))
> > > > > > return PTR_ERR(gobj);
> > > > > > @@ -1805,12 +1824,13 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
> > > > > > {
> > > > > > struct amdkfd_process_info *process_info = mem->process_info;
> > > > > > unsigned long bo_size = mem->bo->tbo.base.size;
> > > > > > + bool is_imported = false;
> > > > > > + struct drm_gem_object *imported_gobj;
> > > > > > struct kfd_mem_attachment *entry, *tmp;
> > > > > > struct bo_vm_reservation_context ctx;
> > > > > > struct ttm_validate_buffer *bo_list_entry;
> > > > > > unsigned int mapped_to_gpu_memory;
> > > > > > int ret;
> > > > > > - bool is_imported = false;
> > > > > > mutex_lock(&mem->lock);
> > > > > > @@ -1885,7 +1905,13 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
> > > > > > }
> > > > > > /* Free the BO*/
> > > > > > - drm_vma_node_revoke(&mem->bo->tbo.base.vma_node, drm_priv);
> > > > > > + if (!is_imported) {
> > > > > > + drm_vma_node_revoke(&mem->bo->tbo.base.vma_node, drm_priv);
> > > > > > + } else {
> > > > > > + imported_gobj = mem->dmabuf->priv;
> > > > > > + drm_vma_node_revoke(&imported_gobj->vma_node, drm_priv);
> > > > > > + }
> > > > > > +
> > > > > > if (mem->dmabuf)
> > > > > > dma_buf_put(mem->dmabuf);
> > > > > > mutex_destroy(&mem->lock);
> > > > > > @@ -2249,62 +2275,77 @@ int amdgpu_amdkfd_gpuvm_import_dmabuf(struct amdgpu_device *adev,
> > > > > > uint64_t *mmap_offset)
> > > > > > {
> > > > > > struct amdgpu_vm *avm = drm_priv_to_vm(drm_priv);
> > > > > > - struct drm_gem_object *obj;
> > > > > > - struct amdgpu_bo *bo;
> > > > > > + struct drm_gem_object *imported_gobj, *gobj;
> > > > > > + struct amdgpu_bo *imported_bo, *bo;
> > > > > > int ret;
> > > > > > - if (dma_buf->ops != &amdgpu_dmabuf_ops)
> > > > > > - /* Can't handle non-graphics buffers */
> > > > > > + /*
> > > > > > + * Can't handle non-graphics buffers and
> > > > > > + * buffers from other devices
> > > > > > + */
> > > > > > + imported_gobj = dma_buf->priv;
> > > > > > + if (dma_buf->ops != &amdgpu_dmabuf_ops ||
> > > > > > + drm_to_adev(imported_gobj->dev) != adev)
> > > > > > return -EINVAL;
> > > > > > - obj = dma_buf->priv;
> > > > > > - if (drm_to_adev(obj->dev) != adev)
> > > > > > - /* Can't handle buffers from other devices */
> > > > > > + /* Only VRAM and GTT BOs are supported */
> > > > > > + imported_bo = gem_to_amdgpu_bo(imported_gobj);
> > > > > > + if (!(imported_bo->preferred_domains &
> > > > > > + (AMDGPU_GEM_DOMAIN_VRAM | AMDGPU_GEM_DOMAIN_GTT)))
> > > > > > return -EINVAL;
> > > > > > - bo = gem_to_amdgpu_bo(obj);
> > > > > > - if (!(bo->preferred_domains & (AMDGPU_GEM_DOMAIN_VRAM |
> > > > > > - AMDGPU_GEM_DOMAIN_GTT)))
> > > > > > - /* Only VRAM and GTT BOs are supported */
> > > > > > - return -EINVAL;
> > > > > > + ret = drm_vma_node_allow(&imported_gobj->vma_node, drm_priv);
> > > > > > + if (ret)
> > > > > > + return ret;
> > > > > > - *mem = kzalloc(sizeof(struct kgd_mem), GFP_KERNEL);
> > > > > > - if (!*mem)
> > > > > > - return -ENOMEM;
> > > > > > + gobj = amdgpu_amdkfd_import(adev_to_drm(adev), dma_buf);
> > > > > > + if (IS_ERR(gobj)) {
> > > > > > + ret = PTR_ERR(gobj);
> > > > > > + goto err_import;
> > > > > > + }
> > > > > > - ret = drm_vma_node_allow(&obj->vma_node, drm_priv);
> > > > > > - if (ret) {
> > > > > > - kfree(mem);
> > > > > > - return ret;
> > > > > > + bo = gem_to_amdgpu_bo(gobj);
> > > > > > + bo->flags |= AMDGPU_GEM_CREATE_PREEMPTIBLE;
> > > > > > +
> > > > > > + *mem = kzalloc(sizeof(struct kgd_mem), GFP_KERNEL);
> > > > > > + if (!*mem) {
> > > > > > + ret = -ENOMEM;
> > > > > > + goto err_alloc_mem;
> > > > > > }
> > > > > > if (size)
> > > > > > - *size = amdgpu_bo_size(bo);
> > > > > > + *size = amdgpu_bo_size(imported_bo);
> > > > > > if (mmap_offset)
> > > > > > - *mmap_offset = amdgpu_bo_mmap_offset(bo);
> > > > > > + *mmap_offset = amdgpu_bo_mmap_offset(imported_bo);
> > > > > > INIT_LIST_HEAD(&(*mem)->attachments);
> > > > > > mutex_init(&(*mem)->lock);
> > > > > > (*mem)->alloc_flags =
> > > > > > - ((bo->preferred_domains & AMDGPU_GEM_DOMAIN_VRAM) ?
> > > > > > + ((imported_bo->preferred_domains & AMDGPU_GEM_DOMAIN_VRAM) ?
> > > > > > KFD_IOC_ALLOC_MEM_FLAGS_VRAM : KFD_IOC_ALLOC_MEM_FLAGS_GTT)
> > > > > > | KFD_IOC_ALLOC_MEM_FLAGS_WRITABLE
> > > > > > | KFD_IOC_ALLOC_MEM_FLAGS_EXECUTABLE;
> > > > > > - drm_gem_object_get(&bo->tbo.base);
> > > > > > + get_dma_buf(dma_buf);
> > > > > > + (*mem)->dmabuf = dma_buf;
> > > > > > (*mem)->bo = bo;
> > > > > > (*mem)->va = va;
> > > > > > - (*mem)->domain = (bo->preferred_domains & AMDGPU_GEM_DOMAIN_VRAM) ?
> > > > > > - AMDGPU_GEM_DOMAIN_VRAM : AMDGPU_GEM_DOMAIN_GTT;
> > > > > > + (*mem)->domain = AMDGPU_GEM_DOMAIN_GTT;
> > > > > > (*mem)->mapped_to_gpu_memory = 0;
> > > > > > (*mem)->process_info = avm->process_info;
> > > > > > add_kgd_mem_to_kfd_bo_list(*mem, avm->process_info, false);
> > > > > > amdgpu_sync_create(&(*mem)->sync);
> > > > > > (*mem)->is_imported = true;
> > > > > > + bo->kfd_bo = *mem;
> > > > > > return 0;
> > > > > > +err_import:
> > > > > > + drm_vma_node_revoke(&imported_gobj->vma_node, drm_priv);
> > > > > > +err_alloc_mem:
> > > > > > + drm_gem_object_put(gobj);
> > > > > > + return ret;
> > > > > > }
> > > > > > /* Evict a userptr BO by stopping the queues if necessary
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