On Thu, 22 Apr 2010 19:13:12 +0900 Minchan Kim <minchan.kim@xxxxxxxxx> wrote: > On Thu, Apr 22, 2010 at 6:46 PM, KAMEZAWA Hiroyuki > <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > > Hmm..in my test, the case was. > > > > Before try_to_unmap: > > mapcount=1, SwapCache, remap_swapcache=1 > > After remap > > mapcount=0, SwapCache, rc=0. > > > > So, I think there may be some race in rmap_walk() and vma handling or > > anon_vma handling. migration_entry isn't found by rmap_walk. > > > > Hmm..it seems this kind patch will be required for debug. > > I looked do_swap_page, again. > lock_page is called long after migration_entry_wait. > It means lock_page can't close the race. > > So I think this BUG is possible. > What do you think? > I think it's not a problem. When migration-entry-wait is called, enry_wait() does pte_lock(); check migration_pte check it's locked. And after wait_on_page_locked(), it just returns to user and cause page fault again. Thanks, -Kame -- 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>