[PATCH v4 23/48] drm/i915: dynamically allocate the i915_gem_mm shrinker

Qi Zheng
2023-08-07T11:30:28Z

In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the i915_gem_mm shrinker, so that it can be freed
asynchronously using kfree_rcu(). Then it doesn't need to wait for RCU
read-side critical section when releasing the struct drm_i915_private.

Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
---
drivers/gpu/drm/i915/gem/i915_gem_shrinker.c | 30 +++++++++++---------
drivers/gpu/drm/i915/i915_drv.h | 2 +-
2 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
index 214763942aa2..4504eb4f31d5 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shrinker.c
@@ -284,8 +284,7 @@ unsigned long i915_gem_shrink_all(struct drm_i915_private *i915)
static unsigned long
i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
{
- struct drm_i915_private *i915 =
- container_of(shrinker, struct drm_i915_private, mm.shrinker);
+ struct drm_i915_private *i915 = shrinker->private_data;
unsigned long num_objects;
unsigned long count;

@@ -302,8 +301,8 @@ i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
if (num_objects) {
unsigned long avg = 2 * count / num_objects;

- i915->mm.shrinker.batch =
- max((i915->mm.shrinker.batch + avg) >> 1,
+ i915->mm.shrinker->batch =
+ max((i915->mm.shrinker->batch + avg) >> 1,
128ul /* default SHRINK_BATCH */);
}

@@ -313,8 +312,7 @@ i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
static unsigned long
i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
{
- struct drm_i915_private *i915 =
- container_of(shrinker, struct drm_i915_private, mm.shrinker);
+ struct drm_i915_private *i915 = shrinker->private_data;
unsigned long freed;

sc->nr_scanned = 0;
@@ -422,12 +420,18 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr

void i915_gem_driver_register__shrinker(struct drm_i915_private *i915)
{
- i915->mm.shrinker.scan_objects = i915_gem_shrinker_scan;
- i915->mm.shrinker.count_objects = i915_gem_shrinker_count;
- i915->mm.shrinker.seeks = DEFAULT_SEEKS;
- i915->mm.shrinker.batch = 4096;
- drm_WARN_ON(&i915->drm, register_shrinker(&i915->mm.shrinker,
- "drm-i915_gem"));
+ i915->mm.shrinker = shrinker_alloc(0, "drm-i915_gem");
+ if (!i915->mm.shrinker) {
+ drm_WARN_ON(&i915->drm, 1);
+ } else {
+ i915->mm.shrinker->scan_objects = i915_gem_shrinker_scan;
+ i915->mm.shrinker->count_objects = i915_gem_shrinker_count;
+ i915->mm.shrinker->seeks = DEFAULT_SEEKS;
+ i915->mm.shrinker->batch = 4096;
+ i915->mm.shrinker->private_data = i915;
+
+ shrinker_register(i915->mm.shrinker);
+ }

i915->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
drm_WARN_ON(&i915->drm, register_oom_notifier(&i915->mm.oom_notifier));
@@ -443,7 +447,7 @@ void i915_gem_driver_unregister__shrinker(struct drm_i915_private *i915)
unregister_vmap_purge_notifier(&i915->mm.vmap_notifier));
drm_WARN_ON(&i915->drm,
unregister_oom_notifier(&i915->mm.oom_notifier));
- unregister_shrinker(&i915->mm.shrinker);
+ shrinker_free(i915->mm.shrinker);
}

void i915_gem_shrinker_taints_mutex(struct drm_i915_private *i915,
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 682ef2b5c7d5..389e8bf140d7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -163,7 +163,7 @@ struct i915_gem_mm {

struct notifier_block oom_notifier;
struct notifier_block vmap_notifier;
- struct shrinker shrinker;
+ struct shrinker *shrinker;

#ifdef CONFIG_MMU_NOTIFIER
/**
--
2.30.2