From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755400AbYLKAxQ (ORCPT ); Wed, 10 Dec 2008 19:53:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752657AbYLKAxA (ORCPT ); Wed, 10 Dec 2008 19:53:00 -0500 Received: from smtp-out.google.com ([216.239.45.13]:38960 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752418AbYLKAxA (ORCPT ); Wed, 10 Dec 2008 19:53:00 -0500 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:in-reply-to:references:date:message-id:subject:from:to: cc:content-type:content-transfer-encoding; b=CRhx2f+1IKnRNs2RPFkn3BfrYTfXEqZFKqJvQZyRKakvPLStuNXTOd4rcOZ6LpYtC L0uNS5ALuMlRODa7i2mOw== MIME-Version: 1.0 In-Reply-To: <20081211094938.85b00cf3.kamezawa.hiroyu@jp.fujitsu.com> References: <20081210233654.563182000@menage.corp.google.com> <20081210234432.236302000@menage.corp.google.com> <20081211094938.85b00cf3.kamezawa.hiroyu@jp.fujitsu.com> Date: Wed, 10 Dec 2008 16:52:57 -0800 Message-ID: <6599ad830812101652o25bc33f3r2a710e0879f9b196@mail.gmail.com> Subject: Re: [RFC][PATCH 2/3] CGroups: Use hierarchy_mutex in memory controller From: Paul Menage To: KAMEZAWA Hiroyuki Cc: balbir@linux.vnet.ibm.com, containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 10, 2008 at 4:49 PM, KAMEZAWA Hiroyuki wrote: > > an operation like rmdir() in somewhere. > hierarchy_lock for A (acquired) > hierarchy_lock for B (waiting) > > in subsys A. > mmap_sem (acquired) > hierarchy_lock for A (waiting) > in subsys B. > hierarchy_lock for B (aquired) > mmap_sem (waiting) > That's a valid deadlock - you'd need to require the mmap_sem nests either inside all hierarchy_mutexes or else outside all of them. Paul