On Thu, Oct 24, 2013 at 05:51:11PM +0800, Weijie Yang wrote: > Consider the following scenario: > thread 0: reclaim entry x (get refcount, but not call > zswap_get_swap_cache_page) > thread 1: call zswap_frontswap_invalidate_page to invalidate entry x. > finished, entry x and its zbud is not freed as its refcount != 0 > now, the swap_map[x] = 0 > thread 0: now call zswap_get_swap_cache_page > swapcache_prepare return -ENOENT because entry x is not used any more > zswap_get_swap_cache_page return ZSWAP_SWAPCACHE_NOMEM > zswap_writeback_entry do nothing except put refcount > Now, the memory of zswap_entry x and its zpage leak. > > Modify: > - check the refcount in fail path, free memory if it is not referenced. > > - use ZSWAP_SWAPCACHE_FAIL instead of ZSWAP_SWAPCACHE_NOMEM as the fail path > can be not only caused by nomem but also by invalidate. > > Signed-off-by: Weijie Yang <[email protected]> > Reviewed-by: Bob Liu <[email protected]> > Cc: Minchan Kim <[email protected]> > Cc: <[email protected]> > Acked-by: Seth Jennings <[email protected]> > Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Minchan Kim <[email protected]> Thanks, Weijie! -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
