[PATCH v3 13/23] drm/msm: Add priv->mm_lock to protect active/inactive lists

From: Rob Clark robdclark@chromium.org

Rather than relying on the big dev->struct_mutex hammer, introduce a more specific lock for protecting the bo lists.

Signed-off-by: Rob Clark robdclark@chromium.org Reviewed-by: Jordan Crouse jcrouse@codeaurora.org --- drivers/gpu/drm/msm/msm_debugfs.c | 7 +++++++ drivers/gpu/drm/msm/msm_drv.c | 7 +++++++ drivers/gpu/drm/msm/msm_drv.h | 13 +++++++++++- drivers/gpu/drm/msm/msm_gem.c | 28 +++++++++++++++----------- drivers/gpu/drm/msm/msm_gem_shrinker.c | 12 +++++++++++ drivers/gpu/drm/msm/msm_gpu.h | 5 ++++- 6 files changed, 58 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_debugfs.c b/drivers/gpu/drm/msm/msm_debugfs.c index ee2e270f464c..64afbed89821 100644 --- a/drivers/gpu/drm/msm/msm_debugfs.c +++ b/drivers/gpu/drm/msm/msm_debugfs.c @@ -112,6 +112,11 @@ static int msm_gem_show(struct drm_device *dev, struct seq_file *m) { struct msm_drm_private *priv = dev->dev_private; struct msm_gpu *gpu = priv->gpu; + int ret; + + ret = mutex_lock_interruptible(&priv->mm_lock); + if (ret) + return ret;

if (gpu) { seq_printf(m, "Active Objects (%s):\n", gpu->name); @@ -121,6 +126,8 @@ static int msm_gem_show(struct drm_device *dev, struct seq_file *m) seq_printf(m, "Inactive Objects:\n"); msm_gem_describe_objects(&priv->inactive_list, m);

+ mutex_unlock(&priv->mm_lock); + return 0; }

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c index 70bc4bb69edc..15c41786d018 100644 --- a/drivers/gpu/drm/msm/msm_drv.c +++ b/drivers/gpu/drm/msm/msm_drv.c @@ -7,6 +7,7 @@

#include <linux/dma-mapping.h> #include <linux/kthread.h> +#include <linux/sched/mm.h> #include <linux/uaccess.h> #include <uapi/linux/sched/types.h>

@@ -468,6 +469,12 @@ static int msm_drm_init(struct device *dev, struct drm_driver *drv) init_llist_head(&priv->free_list);

INIT_LIST_HEAD(&priv->inactive_list); + mutex_init(&priv->mm_lock); + + /* Teach lockdep about lock ordering wrt. shrinker: */ + fs_reclaim_acquire(GFP_KERNEL); + might_lock(&priv->mm_lock); + fs_reclaim_release(GFP_KERNEL);

drm_mode_config_init(ddev);

diff --git a/drivers/gpu/drm/msm/msm_drv.h b/drivers/gpu/drm/msm/msm_drv.h index 713a0ae28125..7431d68ea102 100644 --- a/drivers/gpu/drm/msm/msm_drv.h +++ b/drivers/gpu/drm/msm/msm_drv.h @@ -174,8 +174,19 @@ struct msm_drm_private { struct msm_rd_state *hangrd; /* debugfs to dump hanging submits */ struct msm_perf_state *perf;

- /* list of GEM objects: */ + /* + * List of inactive GEM objects. Every bo is either in the inactive_list + * or gpu->active_list (for the gpu it is active on[1]) + * + * These lists are protected by mm_lock. If struct_mutex is involved, it + * should be aquired prior to mm_lock. One should *not* hold mm_lock in + * get_pages()/vmap()/etc paths, as they can trigger the shrinker. + * + * [1] if someone ever added support for the old 2d cores, there could be + * more than one gpu object + */ struct list_head inactive_list; + struct mutex mm_lock;

/* worker for delayed free of objects: */ struct work_struct free_work; diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c index 3dcb2ef4740f..092ed152999e 100644 --- a/drivers/gpu/drm/msm/msm_gem.c +++ b/drivers/gpu/drm/msm/msm_gem.c @@ -768,13 +768,17 @@ int msm_gem_sync_object(struct drm_gem_object *obj, void msm_gem_active_get(struct drm_gem_object *obj, struct msm_gpu *gpu) { struct msm_gem_object *msm_obj = to_msm_bo(obj); - WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex)); + struct msm_drm_private *priv = obj->dev->dev_private; + + might_sleep(); WARN_ON(msm_obj->madv != MSM_MADV_WILLNEED);

if (!atomic_fetch_inc(&msm_obj->active_count)) { + mutex_lock(&priv->mm_lock); msm_obj->gpu = gpu; list_del_init(&msm_obj->mm_list); list_add_tail(&msm_obj->mm_list, &gpu->active_list); + mutex_unlock(&priv->mm_lock); } }

@@ -783,12 +787,14 @@ void msm_gem_active_put(struct drm_gem_object *obj) struct msm_gem_object *msm_obj = to_msm_bo(obj); struct msm_drm_private *priv = obj->dev->dev_private;

- WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex)); + might_sleep();

if (!atomic_dec_return(&msm_obj->active_count)) { + mutex_lock(&priv->mm_lock); msm_obj->gpu = NULL; list_del_init(&msm_obj->mm_list); list_add_tail(&msm_obj->mm_list, &priv->inactive_list); + mutex_unlock(&priv->mm_lock); } }

@@ -943,13 +949,16 @@ static void free_object(struct msm_gem_object *msm_obj) { struct drm_gem_object *obj = &msm_obj->base; struct drm_device *dev = obj->dev; + struct msm_drm_private *priv = dev->dev_private;

WARN_ON(!mutex_is_locked(&dev->struct_mutex));

/* object should not be on active list: */ WARN_ON(is_active(msm_obj));

+ mutex_lock(&priv->mm_lock); list_del(&msm_obj->mm_list); + mutex_unlock(&priv->mm_lock);

msm_gem_lock(obj);

@@ -1123,14 +1132,9 @@ static struct drm_gem_object *_msm_gem_new(struct drm_device *dev, mapping_set_gfp_mask(obj->filp->f_mapping, GFP_HIGHUSER); }

- if (struct_mutex_locked) { - WARN_ON(!mutex_is_locked(&dev->struct_mutex)); - list_add_tail(&msm_obj->mm_list, &priv->inactive_list); - } else { - mutex_lock(&dev->struct_mutex); - list_add_tail(&msm_obj->mm_list, &priv->inactive_list); - mutex_unlock(&dev->struct_mutex); - } + mutex_lock(&priv->mm_lock); + list_add_tail(&msm_obj->mm_list, &priv->inactive_list); + mutex_unlock(&priv->mm_lock);

return obj;

@@ -1198,9 +1202,9 @@ struct drm_gem_object *msm_gem_import(struct drm_device *dev,

msm_gem_unlock(obj);

- mutex_lock(&dev->struct_mutex); + mutex_lock(&priv->mm_lock); list_add_tail(&msm_obj->mm_list, &priv->inactive_list); - mutex_unlock(&dev->struct_mutex); + mutex_unlock(&priv->mm_lock);

return obj;

diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c b/drivers/gpu/drm/msm/msm_gem_shrinker.c index 2dc0ffa925b4..6be073b8ca08 100644 --- a/drivers/gpu/drm/msm/msm_gem_shrinker.c +++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c @@ -51,6 +51,8 @@ msm_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc) if (!msm_gem_shrinker_lock(dev, &unlock)) return 0;

+ mutex_lock(&priv->mm_lock); + list_for_each_entry(msm_obj, &priv->inactive_list, mm_list) { if (!msm_gem_trylock(&msm_obj->base)) continue; @@ -59,6 +61,8 @@ msm_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc) msm_gem_unlock(&msm_obj->base); }

+ mutex_unlock(&priv->mm_lock); + if (unlock) mutex_unlock(&dev->struct_mutex);

@@ -78,6 +82,8 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) if (!msm_gem_shrinker_lock(dev, &unlock)) return SHRINK_STOP;

+ mutex_lock(&priv->mm_lock); + list_for_each_entry(msm_obj, &priv->inactive_list, mm_list) { if (freed >= sc->nr_to_scan) break; @@ -90,6 +96,8 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) msm_gem_unlock(&msm_obj->base); }

+ mutex_unlock(&priv->mm_lock); + if (unlock) mutex_unlock(&dev->struct_mutex);

@@ -112,6 +120,8 @@ msm_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr) if (!msm_gem_shrinker_lock(dev, &unlock)) return NOTIFY_DONE;

+ mutex_lock(&priv->mm_lock); + list_for_each_entry(msm_obj, &priv->inactive_list, mm_list) { if (!msm_gem_trylock(&msm_obj->base)) continue; @@ -129,6 +139,8 @@ msm_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr) break; }

+ mutex_unlock(&priv->mm_lock); + if (unlock) mutex_unlock(&dev->struct_mutex);

diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h index 6c9e1fdc1a76..1806e87600c0 100644 --- a/drivers/gpu/drm/msm/msm_gpu.h +++ b/drivers/gpu/drm/msm/msm_gpu.h @@ -94,7 +94,10 @@ struct msm_gpu { struct msm_ringbuffer *rb[MSM_GPU_MAX_RINGS]; int nr_rings;

- /* list of GEM active objects: */ + /* + * List of GEM active objects on this gpu. Protected by + * msm_drm_private::mm_lock + */ struct list_head active_list;

/* does gpu need hw_init? */