From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 2/2 v3] cgroup: Drop task_lock(parent) on cgroup_fork() Date: Wed, 21 Dec 2011 11:16:24 -0800 Message-ID: <20111221191624.GK9213@google.com> References: <1324494199-23928-1-git-send-email-fweisbec@gmail.com> <1324494199-23928-3-git-send-email-fweisbec@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=P2lXrBg3nBRWA+ErJ/LJn9vqEzBabtULX3AuIMKxqoc=; b=ZP3q5GPUtbla+6gsnn+/qsOA/blle29O3F90iJmwNEfXcQ5hFKEfqk9wh0Z3A16onn qzh3O5QVtxNXFZWUlg2xWNn8oaaCO/jcrUn/oCyBmDLoPo2m/jv44CxYKiyC1Ie1WY/1 1SBfxQzewFFSg1kwEAxwb0Myb9I89wtoTP8Mw= Content-Disposition: inline In-Reply-To: <1324494199-23928-3-git-send-email-fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Frederic Weisbecker Cc: Containers , LKML , Oleg Nesterov , Mandeep Singh Baines , Cgroups , Andrew Morton , Paul Menage On Wed, Dec 21, 2011 at 08:03:19PM +0100, Frederic Weisbecker wrote: > We don't need to hold the parent task_lock() on the > parent in cgroup_fork() because we are already synchronized > against the two places that may change the parent css_set > concurrently: > > - cgroup_exit(), but the parent obviously can't exit concurrently > - cgroup migration: we are synchronized against threadgroup_lock() > > So we can safely remove the task_lock() there. > > Signed-off-by: Frederic Weisbecker > Cc: Tejun Heo > Cc: Li Zefan > Cc: Containers > Cc: Cgroups > Cc: KAMEZAWA Hiroyuki > Cc: Oleg Nesterov > Cc: Andrew Morton > Cc: Paul Menage > Cc: Mandeep Singh Baines Applied both patches to cgroup/for-3.3 and pushed out to linux-next. Thank you. -- tejun From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754181Ab1LUTQd (ORCPT ); Wed, 21 Dec 2011 14:16:33 -0500 Received: from mail-gx0-f174.google.com ([209.85.161.174]:62251 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752535Ab1LUTQb (ORCPT ); Wed, 21 Dec 2011 14:16:31 -0500 Date: Wed, 21 Dec 2011 11:16:24 -0800 From: Tejun Heo To: Frederic Weisbecker Cc: Li Zefan , LKML , Containers , Cgroups , KAMEZAWA Hiroyuki , Oleg Nesterov , Andrew Morton , Paul Menage , Mandeep Singh Baines Subject: Re: [PATCH 2/2 v3] cgroup: Drop task_lock(parent) on cgroup_fork() Message-ID: <20111221191624.GK9213@google.com> References: <1324494199-23928-1-git-send-email-fweisbec@gmail.com> <1324494199-23928-3-git-send-email-fweisbec@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1324494199-23928-3-git-send-email-fweisbec@gmail.com> 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 On Wed, Dec 21, 2011 at 08:03:19PM +0100, Frederic Weisbecker wrote: > We don't need to hold the parent task_lock() on the > parent in cgroup_fork() because we are already synchronized > against the two places that may change the parent css_set > concurrently: > > - cgroup_exit(), but the parent obviously can't exit concurrently > - cgroup migration: we are synchronized against threadgroup_lock() > > So we can safely remove the task_lock() there. > > Signed-off-by: Frederic Weisbecker > Cc: Tejun Heo > Cc: Li Zefan > Cc: Containers > Cc: Cgroups > Cc: KAMEZAWA Hiroyuki > Cc: Oleg Nesterov > Cc: Andrew Morton > Cc: Paul Menage > Cc: Mandeep Singh Baines Applied both patches to cgroup/for-3.3 and pushed out to linux-next. Thank you. -- tejun