find_get_swapcache_page() question

[Marcelo Tosatti]

Ingo,

Looking at find_get_swapcache_page(), I can't see _how_ we can find a
page on the swapper pagecache table that is not a swapcache page.

How that can happen ?

        spin_lock(&pagecache_lock);
        page = __find_page_nolock(mapping, offset, *hash);
        if (page) {
                spin_lock(&pagemap_lru_lock);
                if (PageSwapCache(page))
                        page_cache_get(page);
                else
                        page = NULL;   <-----
                spin_unlock(&pagemap_lru_lock);
        }
        spin_unlock(&pagecache_lock);