[PATCH] drm/ttm: make the pool shrinker lock a mutex

[Christian König]

Ping? Ray can I get an acked-by? It's an important bug fix.

Thanks,
Christian.

Am 11.01.21 um 14:57 schrieb Christian König:
> set_pages_wb() might sleep and so we can't do this in an atomic context.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov at gmail.com>
> Fixes: d099fc8f540a ("drm/ttm: new TT backend allocation pool v3")
> ---
>   drivers/gpu/drm/ttm/ttm_pool.c | 20 ++++++++++----------
>   1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
> index a00b7ab9c14c..6a6eeba423d1 100644
> --- a/drivers/gpu/drm/ttm/ttm_pool.c
> +++ b/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) {