drm/ttm: make the pool shrinker lock a mutex

set_pages_wb() might sleep and so we can't do this in an atomic context.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Fixes: d099fc8f ("drm/ttm: new TT backend allocation pool v3")
Reviewed-by: Huang Rui <ray.huang@amd.com>
Link: https://patchwork.freedesktop.org/patch/413409/

drivers/gpu/drm/ttm/ttm_pool.c

@@ -66,7 +66,7 @@ static struct ttm_pool_type global_uncached[MAX_ORDER];
 static struct ttm_pool_type global_dma32_write_combined[MAX_ORDER];
 static struct ttm_pool_type global_dma32_uncached[MAX_ORDER];
 
-static spinlock_t shrinker_lock;
+static struct mutex shrinker_lock;
 static struct list_head shrinker_list;
 static struct shrinker mm_shrinker;
 
@@ -249,9 +249,9 @@ static void ttm_pool_type_init(struct ttm_pool_type *pt, struct ttm_pool *pool,
 	spin_lock_init(&pt->lock);
 	INIT_LIST_HEAD(&pt->pages);
 
-	spin_lock(&shrinker_lock);
+	mutex_lock(&shrinker_lock);
 	list_add_tail(&pt->shrinker_list, &shrinker_list);
-	spin_unlock(&shrinker_lock);
+	mutex_unlock(&shrinker_lock);
 }
 
 /* Remove a pool_type from the global shrinker list and free all pages */
@@ -259,9 +259,9 @@ static void ttm_pool_type_fini(struct ttm_pool_type *pt)
 {
 	struct page *p, *tmp;
 
-	spin_lock(&shrinker_lock);
+	mutex_lock(&shrinker_lock);
 	list_del(&pt->shrinker_list);
-	spin_unlock(&shrinker_lock);
+	mutex_unlock(&shrinker_lock);
 
 	list_for_each_entry_safe(p, tmp, &pt->pages, lru)
 		ttm_pool_free_page(pt->pool, pt->caching, pt->order, p);
@@ -302,7 +302,7 @@ static unsigned int ttm_pool_shrink(void)
 	unsigned int num_freed;
 	struct page *p;
 
-	spin_lock(&shrinker_lock);
+	mutex_lock(&shrinker_lock);
 	pt = list_first_entry(&shrinker_list, typeof(*pt), shrinker_list);
 
 	p = ttm_pool_type_take(pt);
@@ -314,7 +314,7 @@ static unsigned int ttm_pool_shrink(void)
 	}
 
 	list_move_tail(&pt->shrinker_list, &shrinker_list);
-	spin_unlock(&shrinker_lock);
+	mutex_unlock(&shrinker_lock);
 
 	return num_freed;
 }
@@ -564,7 +564,7 @@ int ttm_pool_debugfs(struct ttm_pool *pool, struct seq_file *m)
 {
 	unsigned int i;
 
-	spin_lock(&shrinker_lock);
+	mutex_lock(&shrinker_lock);
 
 	seq_puts(m, "\t ");
 	for (i = 0; i < MAX_ORDER; ++i)
@@ -600,7 +600,7 @@ int ttm_pool_debugfs(struct ttm_pool *pool, struct seq_file *m)
 	seq_printf(m, "\ntotal\t: %8lu of %8lu\n",
 		   atomic_long_read(&allocated_pages), page_pool_size);
 
-	spin_unlock(&shrinker_lock);
+	mutex_unlock(&shrinker_lock);
 
 	return 0;
 }
@@ -644,7 +644,7 @@ int ttm_pool_mgr_init(unsigned long num_pages)
 	if (!page_pool_size)
 		page_pool_size = num_pages;
 
-	spin_lock_init(&shrinker_lock);
+	mutex_init(&shrinker_lock);
 	INIT_LIST_HEAD(&shrinker_list);
 
 	for (i = 0; i < MAX_ORDER; ++i) {