Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755063Ab0FKGM0 (ORCPT ); Fri, 11 Jun 2010 02:12:26 -0400 Received: from e1.ny.us.ibm.com ([32.97.182.141]:39648 "EHLO e1.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752522Ab0FKGMZ (ORCPT ); Fri, 11 Jun 2010 02:12:25 -0400 Date: Fri, 11 Jun 2010 11:41:02 +0530 From: Balbir Singh To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "nishimura@mxp.nes.nec.co.jp" , "linux-kernel@vger.kernel.org" Subject: Re: [RFC][PATCH] memcg remove css_get/put per pages v2 Message-ID: <20100611061102.GF5191@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20100608121901.3cab9bdf.kamezawa.hiroyu@jp.fujitsu.com> <20100609155940.dd121130.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20100609155940.dd121130.kamezawa.hiroyu@jp.fujitsu.com> User-Agent: Mutt/1.5.20 (2009-12-10) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 903 Lines: 28 * KAMEZAWA Hiroyuki [2010-06-09 15:59:40]: > + if (consume_stock(mem)) { > + /* > + * It seems dagerous to access memcg without css_get(). > + * But considering how consume_stok works, it's not > + * necessary. If consume_stock success, some charges > + * from this memcg are cached on this cpu. So, we > + * don't need to call css_get()/css_tryget() before > + * calling consume_stock(). > + */ > + rcu_read_unlock(); > + goto done; > + } > + if (!css_tryget(&mem->css)) { If tryget fails, can one assume that this due to a race and the mem is about to be freed? -- Three Cheers, Balbir -- 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/