On Wed, 2007-08-22 at 11:52 +0900, KAMEZAWA Hiroyuki wrote: > On Wed, 22 Aug 2007 10:08:09 +0800 > Shaohua Li <[EMAIL PROTECTED]> wrote: > > > commit dc386d4d1e98bb39fb967ee156cd456c802fc692 adds rcu_read_lock, but > > some routines in the lock range might sleep (like lock_buffer, > > aops->writepage), I saw a 'sleep in atomic' warning. It appears the > > patch has several versions before. Doing rcu_read_lock in PageAnon > > sounds break the case of PageAnon(page) && PageSwapCache(page), > > as .writepage might be called. The dummy anon patch maybe is ok. > > > > Thank you for catching. > > Maybe you're correct. > > BTW, in PageAnon(page) && PageSwapCache(page) case, I can't find when > .writepage is called. Could you explain ? > > In my understanding, > > rcu_read_lock() > -> try_to_unmap() > -> move_to_new_page() > -> migrate_page() // swap has .migratepage member. > -> migrate_page_move_mapping(). > -> migrate_page_copy(). > -> remove_migration_ptes(). > > > At quick glance, above path has no writepage() ops. > just replace swap's radix tree entry. I missed swap has .migratepage and thought fallback_migrate_page is used, then I thought doing rcu lock in PageAnon case is ok.
Thanks, Shaohua - 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/
