i got the answer for , why pages removed from process address space thru zap_page_range not freed to the free list.....its a comment from filemap.c /* * Application no longer needs these pages. If the pages are dirty, * it's OK to just throw them away. The app will be more careful about * data it wants to keep. Be sure to free swap resources too. The * zap_page_range call sets things up for refill_inactive to actually free * these pages later if no one else has touched them in the meantime, * although we could add these pages to a global reuse list for * */ -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/