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... > stock->nr_pages = 0; > } > stock->cached = NULL; > @@ -2513,6 +2514,7 @@ bypass: > return -EINTR; > > done_restock: > + css_get_many(&memcg->css, batch); > if (batch > nr_pages) > refill_stock(memcg, batch - nr_pages); > done: [...] -- Michal Hocko SUSE Labs -- 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>