On Thu, Apr 15, 2021 at 07:56:24PM +0800, Christian König wrote:
> Switch back to using a spinlock again by moving the IOMMU unmap outside
> of the locked region.
>
> v2: Add a comment explaining why we need sync_shrinkers().
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
Series look good for me as well.
Acked-by: Huang Rui <ray.huang@xxxxxxx>
> ---
> drivers/gpu/drm/ttm/ttm_pool.c | 44 +++++++++++++++++-----------------
> 1 file changed, 22 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_pool.c b/drivers/gpu/drm/ttm/ttm_pool.c
> index cb38b1a17b09..955836d569cc 100644
> --- a/drivers/gpu/drm/ttm/ttm_pool.c
> +++ b/drivers/gpu/drm/ttm/ttm_pool.c
> @@ -70,7 +70,7 @@ 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 struct mutex shrinker_lock;
> +static spinlock_t shrinker_lock;
> static struct list_head shrinker_list;
> static struct shrinker mm_shrinker;
>
> @@ -263,9 +263,9 @@ 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);
>
> - mutex_lock(&shrinker_lock);
> + spin_lock(&shrinker_lock);
> list_add_tail(&pt->shrinker_list, &shrinker_list);
> - mutex_unlock(&shrinker_lock);
> + spin_unlock(&shrinker_lock);
> }
>
> /* Remove a pool_type from the global shrinker list and free all pages */
> @@ -273,9 +273,9 @@ static void ttm_pool_type_fini(struct ttm_pool_type *pt)
> {
> struct page *p;
>
> - mutex_lock(&shrinker_lock);
> + spin_lock(&shrinker_lock);
> list_del(&pt->shrinker_list);
> - mutex_unlock(&shrinker_lock);
> + spin_unlock(&shrinker_lock);
>
> while ((p = ttm_pool_type_take(pt)))
> ttm_pool_free_page(pt->pool, pt->caching, pt->order, p);
> @@ -313,24 +313,19 @@ static struct ttm_pool_type *ttm_pool_select_type(struct ttm_pool *pool,
> static unsigned int ttm_pool_shrink(void)
> {
> struct ttm_pool_type *pt;
> - unsigned int num_freed;
> struct page *p;
>
> - mutex_lock(&shrinker_lock);
> + spin_lock(&shrinker_lock);
> pt = list_first_entry(&shrinker_list, typeof(*pt), shrinker_list);
> + list_move_tail(&pt->shrinker_list, &shrinker_list);
> + spin_unlock(&shrinker_lock);
>
> p = ttm_pool_type_take(pt);
> - if (p) {
> - ttm_pool_free_page(pt->pool, pt->caching, pt->order, p);
> - num_freed = 1 << pt->order;
> - } else {
> - num_freed = 0;
> - }
> -
> - list_move_tail(&pt->shrinker_list, &shrinker_list);
> - mutex_unlock(&shrinker_lock);
> + if (!p)
> + return 0;
>
> - return num_freed;
> + ttm_pool_free_page(pt->pool, pt->caching, pt->order, p);
> + return 1 << pt->order;
> }
>
> /* Return the allocation order based for a page */
> @@ -530,6 +525,11 @@ void ttm_pool_fini(struct ttm_pool *pool)
> for (j = 0; j < MAX_ORDER; ++j)
> ttm_pool_type_fini(&pool->caching[i].orders[j]);
> }
> +
> + /* We removed the pool types from the LRU, but we need to also make sure
> + * that no shrinker is concurrently freeing pages from the pool.
> + */
> + sync_shrinkers();
> }
>
> /* As long as pages are available make sure to release at least one */
> @@ -604,7 +604,7 @@ static int ttm_pool_debugfs_globals_show(struct seq_file *m, void *data)
> {
> ttm_pool_debugfs_header(m);
>
> - mutex_lock(&shrinker_lock);
> + spin_lock(&shrinker_lock);
> seq_puts(m, "wc\t:");
> ttm_pool_debugfs_orders(global_write_combined, m);
> seq_puts(m, "uc\t:");
> @@ -613,7 +613,7 @@ static int ttm_pool_debugfs_globals_show(struct seq_file *m, void *data)
> ttm_pool_debugfs_orders(global_dma32_write_combined, m);
> seq_puts(m, "uc 32\t:");
> ttm_pool_debugfs_orders(global_dma32_uncached, m);
> - mutex_unlock(&shrinker_lock);
> + spin_unlock(&shrinker_lock);
>
> ttm_pool_debugfs_footer(m);
>
> @@ -640,7 +640,7 @@ int ttm_pool_debugfs(struct ttm_pool *pool, struct seq_file *m)
>
> ttm_pool_debugfs_header(m);
>
> - mutex_lock(&shrinker_lock);
> + spin_lock(&shrinker_lock);
> for (i = 0; i < TTM_NUM_CACHING_TYPES; ++i) {
> seq_puts(m, "DMA ");
> switch (i) {
> @@ -656,7 +656,7 @@ int ttm_pool_debugfs(struct ttm_pool *pool, struct seq_file *m)
> }
> ttm_pool_debugfs_orders(pool->caching[i].orders, m);
> }
> - mutex_unlock(&shrinker_lock);
> + spin_unlock(&shrinker_lock);
>
> ttm_pool_debugfs_footer(m);
> return 0;
> @@ -693,7 +693,7 @@ int ttm_pool_mgr_init(unsigned long num_pages)
> if (!page_pool_size)
> page_pool_size = num_pages;
>
> - mutex_init(&shrinker_lock);
> + spin_lock_init(&shrinker_lock);
> INIT_LIST_HEAD(&shrinker_list);
>
> for (i = 0; i < MAX_ORDER; ++i) {
> --
> 2.25.1
>
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