From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-bk0-f53.google.com (mail-bk0-f53.google.com [209.85.214.53]) by kanga.kvack.org (Postfix) with ESMTP id 52C1C6B004D for ; Tue, 11 Mar 2014 21:29:01 -0400 (EDT) Received: by mail-bk0-f53.google.com with SMTP id r7so1351630bkg.26 for ; Tue, 11 Mar 2014 18:29:00 -0700 (PDT) Received: from zene.cmpxchg.org (zene.cmpxchg.org. [2a01:238:4224:fa00:ca1f:9ef3:caee:a2bd]) by mx.google.com with ESMTPS id mb3si5660111bkb.307.2014.03.11.18.28.59 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 11 Mar 2014 18:29:00 -0700 (PDT) From: Johannes Weiner Subject: [patch 6/8] memcg: get_mem_cgroup_from_mm() Date: Tue, 11 Mar 2014 21:28:32 -0400 Message-Id: <1394587714-6966-7-git-send-email-hannes@cmpxchg.org> In-Reply-To: <1394587714-6966-1-git-send-email-hannes@cmpxchg.org> References: <1394587714-6966-1-git-send-email-hannes@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Michal Hocko , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Instead of returning NULL from try_get_mem_cgroup_from_mm() when the mm owner is exiting, just return root_mem_cgroup. This makes sense for all callsites and gets rid of some of them having to fallback manually. Signed-off-by: Johannes Weiner Acked-by: Michal Hocko --- mm/memcontrol.c | 18 ++++-------------- 1 file changed, 4 insertions(+), 14 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 1780e66ec61e..cc7f3ca3ef34 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1071,7 +1071,7 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) return mem_cgroup_from_css(task_css(p, mem_cgroup_subsys_id)); } -struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm) +struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm) { struct mem_cgroup *memcg = NULL; @@ -1079,7 +1079,7 @@ struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm) do { memcg = mem_cgroup_from_task(rcu_dereference(mm->owner)); if (unlikely(!memcg)) - break; + memcg = root_mem_cgroup; } while (!css_tryget(&memcg->css)); rcu_read_unlock(); return memcg; @@ -1475,7 +1475,7 @@ bool task_in_mem_cgroup(struct task_struct *task, p = find_lock_task_mm(task); if (p) { - curr = try_get_mem_cgroup_from_mm(p->mm); + curr = get_mem_cgroup_from_mm(p->mm); task_unlock(p); } else { /* @@ -1489,8 +1489,6 @@ bool task_in_mem_cgroup(struct task_struct *task, css_get(&curr->css); rcu_read_unlock(); } - if (!curr) - return false; /* * We should check use_hierarchy of "memcg" not "curr". Because checking * use_hierarchy of "curr" here make this function true if hierarchy is @@ -3649,15 +3647,7 @@ __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **_memcg, int order) if (!current->mm || current->memcg_kmem_skip_account) return true; - memcg = try_get_mem_cgroup_from_mm(current->mm); - - /* - * very rare case described in mem_cgroup_from_task. Unfortunately there - * isn't much we can do without complicating this too much, and it would - * be gfp-dependent anyway. Just let it go - */ - if (unlikely(!memcg)) - return true; + memcg = get_mem_cgroup_from_mm(current->mm); if (!memcg_can_account_kmem(memcg)) { css_put(&memcg->css); -- 1.9.0 -- 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