On (22/11/18 16:15), Nhat Pham wrote:
[..]
> +static int zs_reclaim_page(struct zs_pool *pool, unsigned int retries)
> +{
> + int i, obj_idx, ret = 0;
> + unsigned long handle;
> + struct zspage *zspage;
> + struct page *page;
> + enum fullness_group fullness;
> +
> + /* Lock LRU and fullness list */
> + spin_lock(&pool->lock);
> + if (list_empty(&pool->lru)) {
> + spin_unlock(&pool->lock);
> + return -EINVAL;
> + }
> +
> + for (i = 0; i < retries; i++) {
> + struct size_class *class;
> +
> + zspage = list_last_entry(&pool->lru, struct zspage, lru);
> + list_del(&zspage->lru);
> +
> + /* zs_free may free objects, but not the zspage and handles */
> + zspage->under_reclaim = true;
> +
> + class = zspage_class(pool, zspage);
> + fullness = get_fullness_group(class, zspage);
> +
> + /* Lock out object allocations and object compaction */
> + remove_zspage(class, zspage, fullness);
> +
> + spin_unlock(&pool->lock);
> +
> + /* Lock backing pages into place */
> + lock_zspage(zspage);
> +
> + obj_idx = 0;
> + page = zspage->first_page;
> + while (1) {
> + handle = find_alloced_obj(class, page, &obj_idx);
> + if (!handle) {
> + page = get_next_page(page);
> + if (!page)
> + break;
> + obj_idx = 0;
> + continue;
> + }
> +
> + /*
> + * This will write the object and call zs_free.
> + *
> + * zs_free will free the object, but the
> + * under_reclaim flag prevents it from freeing
> + * the zspage altogether. This is necessary so
> + * that we can continue working with the
> + * zspage potentially after the last object
> + * has been freed.
> + */
> + ret = pool->zpool_ops->evict(pool->zpool, handle);
> + if (ret)
> + goto next;
> +
> + obj_idx++;
> + }
> +
> +next:
> + /* For freeing the zspage, or putting it back in the pool and LRU list. */
> + spin_lock(&pool->lock);
> + zspage->under_reclaim = false;
> +
> + if (!get_zspage_inuse(zspage)) {
> + /*
> + * Fullness went stale as zs_free() won't touch it
> + * while the page is removed from the pool. Fix it
> + * up for the check in __free_zspage().
> + */
> + zspage->fullness = ZS_EMPTY;
> +
> + __free_zspage(pool, class, zspage);
> + spin_unlock(&pool->lock);
> + return 0;
> + }
> +
> + putback_zspage(class, zspage);
> + list_add(&zspage->lru, &pool->lru);
> + unlock_zspage(zspage);
We probably better to cond_resched() somewhere here. Or in zs_zpool_shrink()
loop.
> + }
> +
> + spin_unlock(&pool->lock);
> + return -EAGAIN;
> +}
