From cc926f78420705817b807dbec0c5d3643827eba3 Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Tue, 29 May 2012 15:07:04 -0700 Subject: memcg: move charges to root cgroup if use_hierarchy=0 Presently, at removal of cgroup, ->pre_destroy() is called and moves charges to the parent cgroup. A major reason for returning -EBUSY from ->pre_destroy() is that the 'moving' hits the parent's resource limitation. It happens only when use_hierarchy=0. Considering use_hierarchy=0, all cgroups should be flat. So, no one cannot justify moving charges to parent...parent and children are in flat configuration, not hierarchical. This patch modifes the code to move charges to the root cgroup at rmdir/force_empty if use_hierarchy==0. This will much simplify rmdir() and reduce error in ->pre_destroy. Signed-off-by: KAMEZAWA Hiroyuki Cc: Aneesh Kumar K.V Cc: Michal Hocko Cc: Johannes Weiner Cc: Frederic Weisbecker Cc: Ying Han Cc: Glauber Costa Reviewed-by: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 34 +++++++++++----------------------- 1 file changed, 11 insertions(+), 23 deletions(-) (limited to 'mm') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 1262a8bc402..96cd9ebefb2 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2678,15 +2678,13 @@ static int mem_cgroup_move_parent(struct page *page, struct mem_cgroup *child, gfp_t gfp_mask) { - struct cgroup *cg = child->css.cgroup; - struct cgroup *pcg = cg->parent; struct mem_cgroup *parent; unsigned int nr_pages; unsigned long uninitialized_var(flags); int ret; /* Is ROOT ? */ - if (!pcg) + if (mem_cgroup_is_root(child)) return -EINVAL; ret = -EBUSY; @@ -2697,33 +2695,23 @@ static int mem_cgroup_move_parent(struct page *page, nr_pages = hpage_nr_pages(page); - parent = mem_cgroup_from_cont(pcg); - if (!parent->use_hierarchy) { - ret = __mem_cgroup_try_charge(NULL, - gfp_mask, nr_pages, &parent, false); - if (ret) - goto put_back; - } + parent = parent_mem_cgroup(child); + /* + * If no parent, move charges to root cgroup. + */ + if (!parent) + parent = root_mem_cgroup; if (nr_pages > 1) flags = compound_lock_irqsave(page); - if (parent->use_hierarchy) { - ret = mem_cgroup_move_account(page, nr_pages, - pc, child, parent, false); - if (!ret) - __mem_cgroup_cancel_local_charge(child, nr_pages); - } else { - ret = mem_cgroup_move_account(page, nr_pages, - pc, child, parent, true); - - if (ret) - __mem_cgroup_cancel_charge(parent, nr_pages); - } + ret = mem_cgroup_move_account(page, nr_pages, + pc, child, parent, false); + if (!ret) + __mem_cgroup_cancel_local_charge(child, nr_pages); if (nr_pages > 1) compound_unlock_irqrestore(page, flags); -put_back: putback_lru_page(page); put: put_page(page); -- cgit v1.2.3-70-g09d2