On Wed, Oct 15, 2014 at 05:18:36PM +0200, Michal Hocko wrote: > On Tue 14-10-14 12:20:34, Johannes Weiner wrote: > > Charges currently pin the css indirectly by playing tricks during > > css_offline(): user pages stall the offlining process until all of > > them have been reparented, whereas kmemcg acquires a keep-alive > > reference if outstanding kernel pages are detected at that point. > > > > In preparation for removing all this complexity, make the pinning > > explicit and acquire a css references for every charged page. > > > > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> > > Reviewed-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> > > Acked-by: Michal Hocko <mhocko@xxxxxxx> > > > --- > > include/linux/cgroup.h | 26 +++++++++++++++++++++++ > > include/linux/percpu-refcount.h | 47 +++++++++++++++++++++++++++++++++-------- > > mm/memcontrol.c | 21 ++++++++++++++---- > > 3 files changed, 81 insertions(+), 13 deletions(-) > > > [...] > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > > index 67dabe8b0aa6..a3feead6be15 100644 > > --- a/mm/memcontrol.c > > +++ b/mm/memcontrol.c > > @@ -2256,6 +2256,7 @@ static void drain_stock(struct memcg_stock_pcp *stock) > > page_counter_uncharge(&old->memory, stock->nr_pages); > > if (do_swap_account) > > page_counter_uncharge(&old->memsw, stock->nr_pages); > > + css_put_many(&old->css, stock->nr_pages); > > I have suggested to add a comment about pairing css_get here because the > corresponding refill_stock doesn't take any reference which might be > little bit confusing. Nothing earth shattering of course... Ah, but this isn't the counter-part to refill_stock(), consume_stock() is. The references are taken for the charges, and those two functions do not change the account. css get/put pair exactly like page counter charge/uncharge. -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>