From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx126.postini.com [74.125.245.126]) by kanga.kvack.org (Postfix) with SMTP id EBDCA6B005D for ; Tue, 3 Jul 2012 22:58:52 -0400 (EDT) Received: from m4.gw.fujitsu.co.jp (unknown [10.0.50.74]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id EC1CC3EE0B6 for ; Wed, 4 Jul 2012 11:58:50 +0900 (JST) Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id D30AC45DE50 for ; Wed, 4 Jul 2012 11:58:50 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id BE0D645DE4D for ; Wed, 4 Jul 2012 11:58:50 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id B2CB31DB8037 for ; Wed, 4 Jul 2012 11:58:50 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.240.81.134]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 6AC341DB803E for ; Wed, 4 Jul 2012 11:58:50 +0900 (JST) Message-ID: <4FF3B0DC.5090508@jp.fujitsu.com> Date: Wed, 04 Jul 2012 11:56:28 +0900 From: Kamezawa Hiroyuki MIME-Version: 1.0 Subject: [PATCH v2 1/2] memcg: add res_counter_usage_safe() Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm Cc: David Rientjes , Andrew Morton , Michal Hocko , Tejun Heo , Johannes Weiner I think usage > limit means a sign of BUG. But, sometimes, res_counter_charge_nofail() is very convenient. tcp_memcg uses it. And I'd like to use it for helping page migration. This patch adds res_counter_usage_safe() which returns min(usage,limit). By this we can use res_counter_charge_nofail() without breaking user experience. Changelog: - read res_counter directrly under lock. - fixed comment. Acked-by: Glauber Costa Acked-by: David Rientjes Reviewed-by: Michal Hocko Signed-off-by: KAMEZAWA Hiroyuki --- include/linux/res_counter.h | 2 ++ kernel/res_counter.c | 18 ++++++++++++++++++ net/ipv4/tcp_memcontrol.c | 2 +- 3 files changed, 21 insertions(+), 1 deletions(-) diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h index 7d7fbe2..a6f8cc5 100644 --- a/include/linux/res_counter.h +++ b/include/linux/res_counter.h @@ -226,4 +226,6 @@ res_counter_set_soft_limit(struct res_counter *cnt, return 0; } +u64 res_counter_usage_safe(struct res_counter *cnt); + #endif diff --git a/kernel/res_counter.c b/kernel/res_counter.c index ad581aa..f0507cd 100644 --- a/kernel/res_counter.c +++ b/kernel/res_counter.c @@ -171,6 +171,24 @@ u64 res_counter_read_u64(struct res_counter *counter, int member) } #endif +/* + * Returns usage. If usage > limit, limit is returned. + * This is useful not to break user experiance if the excess + * is temporary. + */ +u64 res_counter_usage_safe(struct res_counter *counter) +{ + unsigned long flags; + u64 usage, limit; + + spin_lock_irqsave(&counter->lock, flags); + limit = counter->limit; + usage = counter->usage; + spin_unlock_irqrestore(&counter->lock, flags); + + return min(usage, limit); +} + int res_counter_memparse_write_strategy(const char *buf, unsigned long long *res) { diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c index b6f3583..a73dce6 100644 --- a/net/ipv4/tcp_memcontrol.c +++ b/net/ipv4/tcp_memcontrol.c @@ -180,7 +180,7 @@ static u64 tcp_read_usage(struct mem_cgroup *memcg) return atomic_long_read(&tcp_memory_allocated) << PAGE_SHIFT; tcp = tcp_from_cgproto(cg_proto); - return res_counter_read_u64(&tcp->tcp_memory_allocated, RES_USAGE); + return res_counter_usage_safe(&tcp->tcp_memory_allocated); } static u64 tcp_cgroup_read(struct cgroup *cont, struct cftype *cft) -- 1.7.4.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org