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From:   Qi Zheng <zhengqi.arch@bytedance.com>
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        linux-btrfs@vger.kernel.org, Qi Zheng <zhengqi.arch@bytedance.com>
Subject: [PATCH 03/29] drm/i915: dynamically allocate the i915_gem_mm shrinker
Date:   Thu, 22 Jun 2023 16:53:09 +0800
Message-Id: <20230622085335.77010-4-zhengqi.arch@bytedance.com>
In-Reply-To: <20230622085335.77010-1-zhengqi.arch@bytedance.com>
References: <20230622085335.77010-1-zhengqi.arch@bytedance.com>
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In preparation for implementing lockless slab shrink,
we need to dynamically allocate the i915_gem_mm shrinker,
so that it can be freed asynchronously by 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>
---
 drivers/gpu/drm/i915/gem/i915_gem_shrinker.c | 27 ++++++++++----------
 drivers/gpu/drm/i915/i915_drv.h              |  3 ++-
 2 files changed, 16 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..4dcdace26a08 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 +420,15 @@ 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_and_init(i915_gem_shrinker_count,
+						    i915_gem_shrinker_scan,
+						    4096, DEFAULT_SEEKS, 0,
+						    i915);
+	if (i915->mm.shrinker &&
+	    register_shrinker(i915->mm.shrinker, "drm-i915_gem")) {
+		shrinker_free(i915->mm.shrinker);
+		drm_WARN_ON(&i915->drm, 1);
+	}
 
 	i915->mm.oom_notifier.notifier_call = i915_gem_shrinker_oom;
 	drm_WARN_ON(&i915->drm, register_oom_notifier(&i915->mm.oom_notifier));
@@ -443,7 +444,7 @@ 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);
+	unregister_and_free_shrinker(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 b4cf6f0f636d..06b04428596d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -163,7 +163,8 @@ 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