On Wed, Jun 16, 2010 at 11:20:24AM +0900, KAMEZAWA Hiroyuki wrote: > BTW, copy_from_user/copy_to_user is _real_ problem, I'm afraid following > much more than memcg. > > handle_mm_fault() > -> handle_pte_fault() > -> do_wp_page() > -> balance_dirty_page_rate_limited() > -> balance_dirty_pages() > -> writeback_inodes_wbc() > -> writeback_inodes_wb() > -> writeback_sb_inodes() > -> writeback_single_inode() > -> do_writepages() > -> generic_write_pages() > -> write_cache_pages() // use on-stack pagevec. > -> writepage() Yes, this is a massive issue. Strangely enough I just wondered about this callstack as balance_dirty_pages is the only place calling into the per-bdi/sb writeback code directly instead of offloading it to the flusher threads. It's something that should be fixed rather quickly IMHO. write_cache_pages and other bits of this writeback code can use quite large amounts of stack. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>