Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758148Ab3DDLZN (ORCPT ); Thu, 4 Apr 2013 07:25:13 -0400 Received: from cantor2.suse.de ([195.135.220.15]:34386 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758054Ab3DDLZL (ORCPT ); Thu, 4 Apr 2013 07:25:11 -0400 Date: Thu, 4 Apr 2013 13:25:05 +0200 From: Michal Hocko To: Li Zefan Cc: linux-mm@kvack.org, LKML , Cgroups , Tejun Heo , Glauber Costa , KAMEZAWA Hiroyuki , Johannes Weiner Subject: Re: [RFC][PATCH 4/7] memcg: use css_get/put for swap memcg Message-ID: <20130404112505.GG29911@dhcp22.suse.cz> References: <515BF233.6070308@huawei.com> <515BF296.3080406@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <515BF296.3080406@huawei.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3915 Lines: 112 On Wed 03-04-13 17:12:54, Li Zefan wrote: > Use css_get/put instead of mem_cgroup_get/put. > > Signed-off-by: Li Zefan Looks good to me. Swapped in pages still use css_tryget so they would fallback to recharge in __mem_cgroup_try_charge_swapin if the group was removed. Acked-by: Michal Hocko Thanks! > --- > mm/memcontrol.c | 26 ++++++++++++++++---------- > 1 file changed, 16 insertions(+), 10 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 877551d..ad576e8 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -4137,12 +4137,12 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype, > unlock_page_cgroup(pc); > /* > * even after unlock, we have memcg->res.usage here and this memcg > - * will never be freed. > + * will never be freed, so it's safe to call css_get(). > */ > memcg_check_events(memcg, page); > if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) { > mem_cgroup_swap_statistics(memcg, true); > - mem_cgroup_get(memcg); > + css_get(&memcg->css); > } > /* > * Migration does not charge the res_counter for the > @@ -4242,7 +4242,7 @@ mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout) > > /* > * record memcg information, if swapout && memcg != NULL, > - * mem_cgroup_get() was called in uncharge(). > + * css_get() was called in uncharge(). > */ > if (do_swap_account && swapout && memcg) > swap_cgroup_record(ent, css_id(&memcg->css)); > @@ -4273,7 +4273,7 @@ void mem_cgroup_uncharge_swap(swp_entry_t ent) > if (!mem_cgroup_is_root(memcg)) > res_counter_uncharge(&memcg->memsw, PAGE_SIZE); > mem_cgroup_swap_statistics(memcg, false); > - mem_cgroup_put(memcg); > + css_put(&memcg->css); > } > rcu_read_unlock(); > } > @@ -4307,11 +4307,14 @@ static int mem_cgroup_move_swap_account(swp_entry_t entry, > * This function is only called from task migration context now. > * It postpones res_counter and refcount handling till the end > * of task migration(mem_cgroup_clear_mc()) for performance > - * improvement. But we cannot postpone mem_cgroup_get(to) > - * because if the process that has been moved to @to does > - * swap-in, the refcount of @to might be decreased to 0. > + * improvement. But we cannot postpone css_get(to) because if > + * the process that has been moved to @to does swap-in, the > + * refcount of @to might be decreased to 0. > + * > + * We are in attach() phase, so the cgroup is guaranteed to be > + * alive, so we can just call css_get(). > */ > - mem_cgroup_get(to); > + css_get(&to->css); > return 0; > } > return -EINVAL; > @@ -6597,6 +6600,7 @@ static void __mem_cgroup_clear_mc(void) > { > struct mem_cgroup *from = mc.from; > struct mem_cgroup *to = mc.to; > + int i; > > /* we must uncharge all the leftover precharges from mc.to */ > if (mc.precharge) { > @@ -6617,7 +6621,9 @@ static void __mem_cgroup_clear_mc(void) > if (!mem_cgroup_is_root(mc.from)) > res_counter_uncharge(&mc.from->memsw, > PAGE_SIZE * mc.moved_swap); > - __mem_cgroup_put(mc.from, mc.moved_swap); > + > + for (i = 0; i < mc.moved_swap; i++) > + css_put(&mc.from->css); > > if (!mem_cgroup_is_root(mc.to)) { > /* > @@ -6627,7 +6633,7 @@ static void __mem_cgroup_clear_mc(void) > res_counter_uncharge(&mc.to->res, > PAGE_SIZE * mc.moved_swap); > } > - /* we've already done mem_cgroup_get(mc.to) */ > + /* we've already done css_get(mc.to) */ > mc.moved_swap = 0; > } > memcg_oom_recover(from); > -- > 1.8.0.2 -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/