On Mon, Aug 05, 2019 at 08:33:57AM -0600, Rob Herring wrote:
> Add support to the shmem GEM helpers for tracking madvise state and
> purging pages. This is based on the msm implementation.
>
> The BO provides a list_head, but the list management is handled outside
> of the shmem helpers as there are different locking requirements.
>
> Cc: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Maxime Ripard <maxime.ripard@xxxxxxxxxxx>
> Cc: Sean Paul <sean@xxxxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Cc: Eric Anholt <eric@xxxxxxxxxx>
> Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_gem_shmem_helper.c | 57 ++++++++++++++++++++++++++
> include/drm/drm_gem_shmem_helper.h | 15 +++++++
> 2 files changed, 72 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
> index 2f64667ac805..4b442576de1c 100644
> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
> @@ -75,6 +75,7 @@ struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t
> shmem = to_drm_gem_shmem_obj(obj);
> mutex_init(&shmem->pages_lock);
> mutex_init(&shmem->vmap_lock);
Maybe a bit late, but for reasons (interop with ttm, which will be more
important once we have dynamic dma-buf) it would be real nice to use the
reservation_obj lock for all this stuff. msm, being struct_mutex based,
isn't a great example here. The downside is that it will be a lot harder
to get msm to use these then, but much better to not spread struct_mutex
inspired locking too far.
Other bit: Wire this all up in a shrinker while at it?
-Daniel
> + INIT_LIST_HEAD(&shmem->madv_list);
>
> /*
> * Our buffers are kept pinned, so allocating them
> @@ -362,6 +363,62 @@ drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
> }
> EXPORT_SYMBOL(drm_gem_shmem_create_with_handle);
>
> +/* Update madvise status, returns true if not purged, else
> + * false or -errno.
> + */
> +int drm_gem_shmem_madvise(struct drm_gem_object *obj, int madv)
> +{
> + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +
> + mutex_lock(&shmem->pages_lock);
> +
> + if (shmem->madv >= 0)
> + shmem->madv = madv;
> +
> + madv = shmem->madv;
> +
> + mutex_unlock(&shmem->pages_lock);
> +
> + return (madv >= 0);
> +}
> +EXPORT_SYMBOL(drm_gem_shmem_madvise);
> +
> +void drm_gem_shmem_purge_locked(struct drm_gem_object *obj)
> +{
> + struct drm_device *dev = obj->dev;
> + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +
> + WARN_ON(!drm_gem_shmem_is_purgeable(shmem));
> +
> + drm_gem_shmem_put_pages_locked(shmem);
> +
> + shmem->madv = -1;
> +
> + drm_vma_node_unmap(&obj->vma_node, dev->anon_inode->i_mapping);
> + drm_gem_free_mmap_offset(obj);
> +
> + /* Our goal here is to return as much of the memory as
> + * is possible back to the system as we are called from OOM.
> + * To do this we must instruct the shmfs to drop all of its
> + * backing pages, *now*.
> + */
> + shmem_truncate_range(file_inode(obj->filp), 0, (loff_t)-1);
> +
> + invalidate_mapping_pages(file_inode(obj->filp)->i_mapping,
> + 0, (loff_t)-1);
> +}
> +EXPORT_SYMBOL(drm_gem_shmem_purge_locked);
> +
> +void drm_gem_shmem_purge(struct drm_gem_object *obj)
> +{
> + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
> +
> + mutex_lock(&shmem->pages_lock);
> + drm_gem_shmem_purge_locked(obj);
> + mutex_unlock(&shmem->pages_lock);
> +}
> +EXPORT_SYMBOL(drm_gem_shmem_purge);
> +
> /**
> * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
> * @file: DRM file structure to create the dumb buffer for
> diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
> index 038b6d313447..ce1600fdfc3e 100644
> --- a/include/drm/drm_gem_shmem_helper.h
> +++ b/include/drm/drm_gem_shmem_helper.h
> @@ -44,6 +44,9 @@ struct drm_gem_shmem_object {
> */
> unsigned int pages_use_count;
>
> + int madv;
> + struct list_head madv_list;
> +
> /**
> * @pages_mark_dirty_on_put:
> *
> @@ -121,6 +124,18 @@ void drm_gem_shmem_unpin(struct drm_gem_object *obj);
> void *drm_gem_shmem_vmap(struct drm_gem_object *obj);
> void drm_gem_shmem_vunmap(struct drm_gem_object *obj, void *vaddr);
>
> +int drm_gem_shmem_madvise(struct drm_gem_object *obj, int madv);
> +
> +static inline bool drm_gem_shmem_is_purgeable(struct drm_gem_shmem_object *shmem)
> +{
> + return (shmem->madv > 0) &&
> + !shmem->vmap_use_count && shmem->sgt &&
> + !shmem->base.dma_buf && !shmem->base.import_attach;
> +}
> +
> +void drm_gem_shmem_purge_locked(struct drm_gem_object *obj);
> +void drm_gem_shmem_purge(struct drm_gem_object *obj);
> +
> struct drm_gem_shmem_object *
> drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
> struct drm_device *dev, size_t size,
> --
> 2.20.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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