ttm/pool: port to list_lru. (v2)

airlied · airlied · commit 444e2a19d7fd · 2026-04-08T06:52:47.000+10:00
This is an initial port of the TTM pools for
write combined and uncached pages to use the list_lru.

This makes the pool's more NUMA aware and avoids
needing separate NUMA pools (later commit enables this).

Cc: Christian Koenig &lt;christian.koenig@amd.com&gt;
Cc: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Dave Chinner &lt;david@fromorbit.com&gt;
Reviewed-by: Christian König &lt;christian.koenig@amd.com&gt;
Signed-off-by: Dave Airlie &lt;airlied@redhat.com&gt;
diff --git a/drivers/gpu/drm/ttm/tests/ttm_device_test.c b/drivers/gpu/drm/ttm/tests/ttm_device_test.c
@@ -176,7 +176,7 @@ static void ttm_device_init_pools(struct kunit *test)
 
 				if (ttm_pool_uses_dma_alloc(pool))
 					KUNIT_ASSERT_FALSE(test,
-							   list_empty(&pt.pages));
+							   !list_lru_count(&pt.pages));
 			}
 		}
 	}
diff --git a/drivers/gpu/drm/ttm/tests/ttm_pool_test.c b/drivers/gpu/drm/ttm/tests/ttm_pool_test.c
@@ -248,15 +248,15 @@ static void ttm_pool_alloc_order_caching_match(struct kunit *test)
 	pool = ttm_pool_pre_populated(test, size, caching);
 
 	pt = &pool->caching[caching].orders[order];
-	KUNIT_ASSERT_FALSE(test, list_empty(&pt->pages));
+	KUNIT_ASSERT_FALSE(test, !list_lru_count(&pt->pages));
 
 	tt = ttm_tt_kunit_init(test, 0, caching, size);
 	KUNIT_ASSERT_NOT_NULL(test, tt);
 
 	err = ttm_pool_alloc(pool, tt, &simple_ctx);
 	KUNIT_ASSERT_EQ(test, err, 0);
 
-	KUNIT_ASSERT_TRUE(test, list_empty(&pt->pages));
+	KUNIT_ASSERT_TRUE(test, !list_lru_count(&pt->pages));
 
 	ttm_pool_free(pool, tt);
 	ttm_tt_fini(tt);
@@ -282,17 +282,17 @@ static void ttm_pool_alloc_caching_mismatch(struct kunit *test)
 	tt = ttm_tt_kunit_init(test, 0, tt_caching, size);
 	KUNIT_ASSERT_NOT_NULL(test, tt);
 
-	KUNIT_ASSERT_FALSE(test, list_empty(&pt_pool->pages));
-	KUNIT_ASSERT_TRUE(test, list_empty(&pt_tt->pages));
+	KUNIT_ASSERT_FALSE(test, !list_lru_count(&pt_pool->pages));
+	KUNIT_ASSERT_TRUE(test, !list_lru_count(&pt_tt->pages));
 
 	err = ttm_pool_alloc(pool, tt, &simple_ctx);
 	KUNIT_ASSERT_EQ(test, err, 0);
 
 	ttm_pool_free(pool, tt);
 	ttm_tt_fini(tt);
 
-	KUNIT_ASSERT_FALSE(test, list_empty(&pt_pool->pages));
-	KUNIT_ASSERT_FALSE(test, list_empty(&pt_tt->pages));
+	KUNIT_ASSERT_FALSE(test, !list_lru_count(&pt_pool->pages));
+	KUNIT_ASSERT_FALSE(test, !list_lru_count(&pt_tt->pages));
 
 	ttm_pool_fini(pool);
 }
@@ -316,17 +316,17 @@ static void ttm_pool_alloc_order_mismatch(struct kunit *test)
 	tt = ttm_tt_kunit_init(test, 0, caching, snd_size);
 	KUNIT_ASSERT_NOT_NULL(test, tt);
 
-	KUNIT_ASSERT_FALSE(test, list_empty(&pt_pool->pages));
-	KUNIT_ASSERT_TRUE(test, list_empty(&pt_tt->pages));
+	KUNIT_ASSERT_FALSE(test, !list_lru_count(&pt_pool->pages));
+	KUNIT_ASSERT_TRUE(test, !list_lru_count(&pt_tt->pages));
 
 	err = ttm_pool_alloc(pool, tt, &simple_ctx);
 	KUNIT_ASSERT_EQ(test, err, 0);
 
 	ttm_pool_free(pool, tt);
 	ttm_tt_fini(tt);
 
-	KUNIT_ASSERT_FALSE(test, list_empty(&pt_pool->pages));
-	KUNIT_ASSERT_FALSE(test, list_empty(&pt_tt->pages));
+	KUNIT_ASSERT_FALSE(test, !list_lru_count(&pt_pool->pages));
+	KUNIT_ASSERT_FALSE(test, !list_lru_count(&pt_tt->pages));
 
 	ttm_pool_fini(pool);
 }
@@ -352,12 +352,12 @@ static void ttm_pool_free_dma_alloc(struct kunit *test)
 	ttm_pool_alloc(pool, tt, &simple_ctx);
 
 	pt = &pool->caching[caching].orders[order];
-	KUNIT_ASSERT_TRUE(test, list_empty(&pt->pages));
+	KUNIT_ASSERT_TRUE(test, !list_lru_count(&pt->pages));
 
 	ttm_pool_free(pool, tt);
 	ttm_tt_fini(tt);
 
-	KUNIT_ASSERT_FALSE(test, list_empty(&pt->pages));
+	KUNIT_ASSERT_FALSE(test, !list_lru_count(&pt->pages));
 
 	ttm_pool_fini(pool);
 }
@@ -383,12 +383,12 @@ static void ttm_pool_free_no_dma_alloc(struct kunit *test)
 	ttm_pool_alloc(pool, tt, &simple_ctx);
 
 	pt = &pool->caching[caching].orders[order];
-	KUNIT_ASSERT_TRUE(test, list_is_singular(&pt->pages));
+	KUNIT_ASSERT_TRUE(test, list_lru_count(&pt->pages) == 1);
 
 	ttm_pool_free(pool, tt);
 	ttm_tt_fini(tt);
 
-	KUNIT_ASSERT_TRUE(test, list_is_singular(&pt->pages));
+	KUNIT_ASSERT_TRUE(test, list_lru_count(&pt->pages) == 1);
 
 	ttm_pool_fini(pool);
 }
@@ -404,11 +404,11 @@ static void ttm_pool_fini_basic(struct kunit *test)
 	pool = ttm_pool_pre_populated(test, size, caching);
 	pt = &pool->caching[caching].orders[order];
 
-	KUNIT_ASSERT_FALSE(test, list_empty(&pt->pages));
+	KUNIT_ASSERT_FALSE(test, !list_lru_count(&pt->pages));
 
 	ttm_pool_fini(pool);
 
-	KUNIT_ASSERT_TRUE(test, list_empty(&pt->pages));
+	KUNIT_ASSERT_TRUE(test, !list_lru_count(&pt->pages));
 }
 
 static struct kunit_case ttm_pool_test_cases[] = {
diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
@@ -132,6 +132,16 @@ static struct list_head shrinker_list;
 static struct shrinker *mm_shrinker;
 static DECLARE_RWSEM(pool_shrink_rwsem);
 
+static int ttm_pool_nid(struct ttm_pool *pool)
+{
+	int nid = NUMA_NO_NODE;
+	if (pool)
+		nid = pool->nid;
+	if (nid == NUMA_NO_NODE)
+		nid = numa_node_id();
+	return nid;
+}
+
 /* Allocate pages of size 1 << order with the given gfp_flags */
 static struct page *ttm_pool_alloc_page(struct ttm_pool *pool, gfp_t gfp_flags,
 					unsigned int order)
@@ -297,30 +307,41 @@ static void ttm_pool_type_give(struct ttm_pool_type *pt, struct page *p)
 			clear_page(page_address(p + i));
 	}
 
-	spin_lock(&pt->lock);
-	list_add(&p->lru, &pt->pages);
-	spin_unlock(&pt->lock);
+	INIT_LIST_HEAD(&p->lru);
+	rcu_read_lock();
+	list_lru_add(&pt->pages, &p->lru, page_to_nid(p), NULL);
+	rcu_read_unlock();
 	atomic_long_add(1 << pt->order, &allocated_pages);
 
 	mod_lruvec_page_state(p, NR_GPU_ACTIVE, -num_pages);
 	mod_lruvec_page_state(p, NR_GPU_RECLAIM, num_pages);
 }
 
+static enum lru_status take_one_from_lru(struct list_head *item,
+					 struct list_lru_one *list,
+					 void *cb_arg)
+{
+	struct page **out_page = cb_arg;
+	struct page *p = container_of(item, struct page, lru);
+	list_lru_isolate(list, item);
+
+	*out_page = p;
+	return LRU_REMOVED;
+}
+
 /* Take pages from a specific pool_type, return NULL when nothing available */
-static struct page *ttm_pool_type_take(struct ttm_pool_type *pt)
+static struct page *ttm_pool_type_take(struct ttm_pool_type *pt, int nid)
 {
-	struct page *p;
+	int ret;
+	struct page *p = NULL;
+	unsigned long nr_to_walk = 1;
 
-	spin_lock(&pt->lock);
-	p = list_first_entry_or_null(&pt->pages, typeof(*p), lru);
-	if (p) {
+	ret = list_lru_walk_node(&pt->pages, nid, take_one_from_lru, (void *)&p, &nr_to_walk);
+	if (ret == 1 && p) {
 		atomic_long_sub(1 << pt->order, &allocated_pages);
 		mod_lruvec_page_state(p, NR_GPU_ACTIVE, (1 << pt->order));
 		mod_lruvec_page_state(p, NR_GPU_RECLAIM, -(1 << pt->order));
-		list_del(&p->lru);
 	}
-	spin_unlock(&pt->lock);
-
 	return p;
 }
 
@@ -331,25 +352,47 @@ static void ttm_pool_type_init(struct ttm_pool_type *pt, struct ttm_pool *pool,
 	pt->pool = pool;
 	pt->caching = caching;
 	pt->order = order;
-	spin_lock_init(&pt->lock);
-	INIT_LIST_HEAD(&pt->pages);
+	list_lru_init(&pt->pages);
 
 	spin_lock(&shrinker_lock);
 	list_add_tail(&pt->shrinker_list, &shrinker_list);
 	spin_unlock(&shrinker_lock);
 }
 
+static enum lru_status pool_move_to_dispose_list(struct list_head *item,
+						 struct list_lru_one *list,
+						 void *cb_arg)
+{
+	struct list_head *dispose = cb_arg;
+
+	list_lru_isolate_move(list, item, dispose);
+
+	return LRU_REMOVED;
+}
+
+static void ttm_pool_dispose_list(struct ttm_pool_type *pt,
+				  struct list_head *dispose)
+{
+	while (!list_empty(dispose)) {
+		struct page *p;
+		p = list_first_entry(dispose, struct page, lru);
+		list_del_init(&p->lru);
+		atomic_long_sub(1 << pt->order, &allocated_pages);
+		ttm_pool_free_page(pt->pool, pt->caching, pt->order, p, true);
+	}
+}
+
 /* Remove a pool_type from the global shrinker list and free all pages */
 static void ttm_pool_type_fini(struct ttm_pool_type *pt)
 {
-	struct page *p;
+	LIST_HEAD(dispose);
 
 	spin_lock(&shrinker_lock);
 	list_del(&pt->shrinker_list);
 	spin_unlock(&shrinker_lock);
 
-	while ((p = ttm_pool_type_take(pt)))
-		ttm_pool_free_page(pt->pool, pt->caching, pt->order, p, true);
+	list_lru_walk(&pt->pages, pool_move_to_dispose_list, &dispose, LONG_MAX);
+	ttm_pool_dispose_list(pt, &dispose);
 }
 
 /* Return the pool_type to use for the given caching and order */
@@ -399,7 +442,7 @@ static unsigned int ttm_pool_shrink(void)
 	list_move_tail(&pt->shrinker_list, &shrinker_list);
 	spin_unlock(&shrinker_lock);
 
-	p = ttm_pool_type_take(pt);
+	p = ttm_pool_type_take(pt, ttm_pool_nid(pt->pool));
 	if (p) {
 		ttm_pool_free_page(pt->pool, pt->caching, pt->order, p, true);
 		num_pages = 1 << pt->order;
@@ -756,7 +799,7 @@ static int __ttm_pool_alloc(struct ttm_pool *pool, struct ttm_tt *tt,
 		p = NULL;
 		pt = ttm_pool_select_type(pool, page_caching, order);
 		if (pt && allow_pools)
-			p = ttm_pool_type_take(pt);
+			p = ttm_pool_type_take(pt, ttm_pool_nid(pool));
 		/*
 		 * If that fails or previously failed, allocate from system.
 		 * Note that this also disallows additional pool allocations using
@@ -1185,16 +1228,7 @@ static unsigned long ttm_pool_shrinker_count(struct shrinker *shrink,
 /* Count the number of pages available in a pool_type */
 static unsigned int ttm_pool_type_count(struct ttm_pool_type *pt)
 {
-	unsigned int count = 0;
-	struct page *p;
-
-	spin_lock(&pt->lock);
-	/* Only used for debugfs, the overhead doesn't matter */
-	list_for_each_entry(p, &pt->pages, lru)
-		++count;
-	spin_unlock(&pt->lock);
-
-	return count;
+	return list_lru_count(&pt->pages);
 }
 
 /* Print a nice header for the order */
diff --git a/include/drm/ttm/ttm_pool.h b/include/drm/ttm/ttm_pool.h
@@ -29,6 +29,7 @@
 #include <linux/mmzone.h>
 #include <linux/llist.h>
 #include <linux/spinlock.h>
+#include <linux/list_lru.h>
 #include <drm/ttm/ttm_caching.h>
 
 struct device;
@@ -45,8 +46,7 @@ struct ttm_tt;
  * @order: the allocation order our pages have
  * @caching: the caching type our pages have
  * @shrinker_list: our place on the global shrinker list
- * @lock: protection of the page list
- * @pages: the list of pages in the pool
+ * @pages: the lru_list of pages in the pool
  */
 struct ttm_pool_type {
 	struct ttm_pool *pool;
@@ -55,8 +55,7 @@ struct ttm_pool_type {
 
 	struct list_head shrinker_list;
 
-	spinlock_t lock;
-	struct list_head pages;
+	struct list_lru pages;
 };
 
 /**
diff --git a/mm/list_lru.c b/mm/list_lru.c
@@ -179,6 +179,7 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item, int nid,
 	unlock_list_lru(l, false);
 	return false;
 }
+EXPORT_SYMBOL_GPL(list_lru_add);
 
 bool list_lru_add_obj(struct list_lru *lru, struct list_head *item)
 {

Original file line number	Diff line number	Diff line change
`@@ -176,7 +176,7 @@ static void ttm_device_init_pools(struct kunit *test)`
`176`	`176`
`177`	`177`	`if (ttm_pool_uses_dma_alloc(pool))`
`178`	`178`	`KUNIT_ASSERT_FALSE(test,`
`179`		`- list_empty(&pt.pages));`
	`179`	`+ !list_lru_count(&pt.pages));`
`180`	`180`	`}`
`181`	`181`	`}`
`182`	`182`	`}`
Original file line number	Diff line number	Diff line change
`@@ -179,6 +179,7 @@ bool list_lru_add(struct list_lru lru, struct list_head item, int nid,`
`179`	`179`	`unlock_list_lru(l, false);`
`180`	`180`	`return false;`
`181`	`181`	`}`
	`182`	`+EXPORT_SYMBOL_GPL(list_lru_add);`
`182`	`183`
`183`	`184`	`bool list_lru_add_obj(struct list_lru lru, struct list_head item)`
`184`	`185`	`{`