On Tue, Jan 24, 2012 at 05:01:40PM +0100, Michal Hocko wrote: > On Tue 24-01-12 15:54:11, Johannes Weiner wrote: > > Hold on, I think this patch is still not complete: end_migration() > > directly uses __mem_cgroup_uncharge_common() with the FORCE charge > > type. This will uncharge all migrated anon pages as cache, when it > > should decide based on PageAnon(used), which is the page where > > ->mapping is intact after migration. > > You are right, I've missed that one as well. Anyway > MEM_CGROUP_CHARGE_TYPE_FORCE is used only in mem_cgroup_end_migration > these days and it got out of sync with its documentation (used by > force_empty) quite some time ago (f817ed48). What about something like > the following on top of the previous patch? > --- > Should be foldet into the previous patch with the updated changelog: > > Mapping of the unused page is not touched during migration (see used one, not unused. unused->mapping is globbered during migration. > page_remove_rmap) so we can rely on it and push the correct charge type > down to __mem_cgroup_uncharge_common from end_migration. The force flag > was misleading anyway. Kinda. It had the effect of skipping the needless page_mapped() / PageCgroupMigration() check, we know the unused page is no longer mapped and cleared the migration flag just a few lines up. But doing the checks is no biggie and it's not worth adding another flag just to skip them. But I guess this should be mentioned in the changelog. -- 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>