On Wed, 21 Mar 2012 18:52:04 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > As discussed before, I post this to fix the spec and implementation of task moving. > Then, do you think what target kernel version should be ? 3.4/3.5 ? > but yes, it may be late for 3.4.... Well, the key information here is "what effect does the bug have upon users". > In documentation, it's said that 'shared anon are not moved'. > But in implementation, the check was wrong. > > if (!move_anon() || page_mapcount(page) > 2) > > Ah, memcg has been moving shared anon pages for a long time. > > Then, here is a discussion about handling of shared anon pages. > > - It's complex > - Now, shared file caches are moved in force. > - It adds unclear check as page_mapcount(). To do correct check, > we should check swap users, etc. > - No one notice this implementation behavior. So, no one get benefit > from the design. > - In general, once task is moved to a cgroup for running, it will not > be moved.... > - Finally, we have control knob as memory.move_charge_at_immigrate. > > Here is a patch to allow moving shared pages, completely. This makes > memcg simpler and fix current broken code. > > Note: > IIUC, libcgroup's cgroup daemon moves tasks after exec(). > So, it's not affected. > libcgroup's command "cgexec" does move itsef to a memcg and call exec() > without fork(). it's not affected. > > Changelog: > - fixed PageAnon() check. > - remove call of lookup_swap_cache() > - fixed Documentation. But you forgot to tell us :( -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>