I think I find a new issue, for integrity of this mail thread, I reply to this mail. It is a concurrence issue either, when duplicate store and reclaim concurrentlly. zswap entry x with offset A is already stored in zswap backend. Consider the following scenario: thread 0: reclaim entry x (get refcount, but not call zswap_get_swap_cache_page) thread 1: store new page with the same offset A, alloc a new zswap entry y. store finished. shrink_page_list() call __remove_mapping(), and now it is not in swap_cache thread 0: zswap_get_swap_cache_page called. old page data is added to swap_cache Now, swap cache has old data rather than new data for offset A. error will happen If do_swap_page() get page from swap_cache. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>