Re: [PATCH 1/2] drm/shmem: Add madvise state and purge helpers

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@collabora.com Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Maxime Ripard maxime.ripard@bootlin.com Cc: Sean Paul sean@poorly.run Cc: David Airlie airlied@linux.ie Cc: Daniel Vetter daniel@ffwll.ch Cc: Eric Anholt eric@anholt.net Signed-off-by: Rob Herring robh@kernel.org

---

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);

• 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;

Hey Rob, Not sure why I didn't notice this earlier, but:

../include/drm/drm_gem_shmem_helper.h:87: warning: Function parameter or member 'madv' not described in 'drm_gem_shmem_object' ../include/drm/drm_gem_shmem_helper.h:87: warning: Function parameter or member 'madv_list' not described in 'drm_gem_shmem_object'

Could you please add some kerneldoc for these?

Sean

• /**
  • @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