From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f171.google.com (mail-wi0-f171.google.com [209.85.212.171]) by kanga.kvack.org (Postfix) with ESMTP id 1D32A6B0036 for ; Thu, 5 Jun 2014 11:47:22 -0400 (EDT) Received: by mail-wi0-f171.google.com with SMTP id cc10so10806394wib.4 for ; Thu, 05 Jun 2014 08:47:21 -0700 (PDT) Received: from radon.swed.at (a.ns.miles-group.at. [95.130.255.143]) by mx.google.com with ESMTPS id a10si892873wiz.51.2014.06.05.08.47.08 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Thu, 05 Jun 2014 08:47:09 -0700 (PDT) Message-ID: <539090F1.7090408@nod.at> Date: Thu, 05 Jun 2014 17:46:57 +0200 From: Richard Weinberger MIME-Version: 1.0 Subject: Re: [RFC][PATCH] oom: Be less verbose if the oom_control event fd has listeners References: <1401976841-3899-1-git-send-email-richard@nod.at> <1401976841-3899-2-git-send-email-richard@nod.at> <20140605141841.GA23796@redhat.com> In-Reply-To: <20140605141841.GA23796@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Oleg Nesterov Cc: hannes@cmpxchg.org, mhocko@suse.cz, bsingharora@gmail.com, kamezawa.hiroyu@jp.fujitsu.com, akpm@linux-foundation.org, vdavydov@parallels.com, tj@kernel.org, handai.szj@taobao.com, rientjes@google.com, rusty@rustcorp.com.au, kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org Am 05.06.2014 16:18, schrieb Oleg Nesterov: > On 06/05, Richard Weinberger wrote: >> >> +int mem_cgroup_has_listeners(struct mem_cgroup *memcg) >> +{ >> + int ret = 0; >> + >> + if (!memcg) >> + goto out; >> + >> + spin_lock(&memcg_oom_lock); >> + ret = !list_empty(&memcg->oom_notify); >> + spin_unlock(&memcg_oom_lock); >> + >> +out: >> + return ret; >> +} > > Do we really need memcg_oom_lock to check list_empty() ? With or without > this lock we can race with list_add/del anyway, and I guess we do not care. Hmm, in mm/memcontrol.c all list_dev/add are under memcg_oom_lock. What do I miss? Thanks, //richard -- 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