From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 4/6] cgroups: forbid pre_destroy callback to fail Date: Thu, 18 Oct 2012 15:41:48 -0700 Message-ID: <20121018224148.GR13370@google.com> References: <1350480648-10905-1-git-send-email-mhocko@suse.cz> <1350480648-10905-5-git-send-email-mhocko@suse.cz> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=D0oCIRKDf2hwW94fy+BaDQlE8fblehxGUVF65yflQzw=; b=rA1ln5NN+M6FOmdcj6btEW3jemNcm+Cu3TU0vINBzuTl8oqwkQkBdrNNgw6sL7zcIi lF39IrXhkhrvwG3dQKh7pUX21FDOLtlUDfCKMsrNFLa/+nc2uscvbLLDV2YtH9EFA43b 7IqQVz1KYu0bC9XwQa0f7yThHmZyOf7aF/D/f9xN6HQHSUXkxOWHzL4auK8StmYRqN8s CSJWqdgmFi7NeO+281Tkoc3KBzTcy+6avjCu4Nd/kNjp0I9dN1ebDESwRkkuvxeu97xE DZ7ZHbdKPrV7c60326iPLTlmRYFrlN/5cjdoj9wG4lHgBStBz6K+iX44rFbSXFEy8KqE 4MAA== Content-Disposition: inline In-Reply-To: <1350480648-10905-5-git-send-email-mhocko@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Michal Hocko Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Li Zefan , Johannes Weiner , KAMEZAWA Hiroyuki , Balbir Singh Hello, Michal. On Wed, Oct 17, 2012 at 03:30:46PM +0200, Michal Hocko wrote: > Now that mem_cgroup_pre_destroy callback doesn't fail finally we can > safely move on and forbit all the callbacks to fail. The last missing > piece is moving cgroup_call_pre_destroy after cgroup_clear_css_refs so > that css_tryget fails so no new charges for the memcg can happen. > The callbacks are also called from within cgroup_lock to guarantee that > no new tasks show up. We could theoretically call them outside of the > lock but then we have to move after CGRP_REMOVED flag is set. > > Signed-off-by: Michal Hocko So, the plan is to do something like the following once memcg is ready. http://thread.gmane.org/gmane.linux.kernel.containers/22559/focus=75251 Note that the patch is broken in a couple places but it does show the general direction. I'd prefer if patch #3 simply makes pre_destroy() return 0 and drop __DEPRECATED_clear_css_refs from mem_cgroup_subsys. Then, I can pull the branch in and drop all the unnecessary cruft. Thanks. -- tejun -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756168Ab2JRWmu (ORCPT ); Thu, 18 Oct 2012 18:42:50 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:54158 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932504Ab2JRWlw (ORCPT ); Thu, 18 Oct 2012 18:41:52 -0400 Date: Thu, 18 Oct 2012 15:41:48 -0700 From: Tejun Heo To: Michal Hocko Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Li Zefan , Johannes Weiner , KAMEZAWA Hiroyuki , Balbir Singh Subject: Re: [PATCH 4/6] cgroups: forbid pre_destroy callback to fail Message-ID: <20121018224148.GR13370@google.com> References: <1350480648-10905-1-git-send-email-mhocko@suse.cz> <1350480648-10905-5-git-send-email-mhocko@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1350480648-10905-5-git-send-email-mhocko@suse.cz> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Michal. On Wed, Oct 17, 2012 at 03:30:46PM +0200, Michal Hocko wrote: > Now that mem_cgroup_pre_destroy callback doesn't fail finally we can > safely move on and forbit all the callbacks to fail. The last missing > piece is moving cgroup_call_pre_destroy after cgroup_clear_css_refs so > that css_tryget fails so no new charges for the memcg can happen. > The callbacks are also called from within cgroup_lock to guarantee that > no new tasks show up. We could theoretically call them outside of the > lock but then we have to move after CGRP_REMOVED flag is set. > > Signed-off-by: Michal Hocko So, the plan is to do something like the following once memcg is ready. http://thread.gmane.org/gmane.linux.kernel.containers/22559/focus=75251 Note that the patch is broken in a couple places but it does show the general direction. I'd prefer if patch #3 simply makes pre_destroy() return 0 and drop __DEPRECATED_clear_css_refs from mem_cgroup_subsys. Then, I can pull the branch in and drop all the unnecessary cruft. Thanks. -- tejun