From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761082AbZFKQAe (ORCPT ); Thu, 11 Jun 2009 12:00:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753963AbZFKQAV (ORCPT ); Thu, 11 Jun 2009 12:00:21 -0400 Received: from mx2.redhat.com ([66.187.237.31]:46351 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753929AbZFKQAU (ORCPT ); Thu, 11 Jun 2009 12:00:20 -0400 Message-ID: <4A3129E3.3010309@redhat.com> Date: Thu, 11 Jun 2009 11:59:31 -0400 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 2.0.0.17 (X11/20080915) MIME-Version: 1.0 To: Wu Fengguang CC: Andrew Morton , LKML , Nick Piggin , Hugh Dickins , Andi Kleen , "chris.mason@oracle.com" , "linux-mm@kvack.org" Subject: Re: [PATCH 2/5] HWPOISON: fix tasklist_lock/anon_vma locking order References: <20090611142239.192891591@intel.com> <20090611144430.540500784@intel.com> In-Reply-To: <20090611144430.540500784@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Wu Fengguang wrote: > To avoid possible deadlock. Proposed by Nick Piggin: > > You have tasklist_lock(R) nesting outside i_mmap_lock, and inside anon_vma > lock. And anon_vma lock nests inside i_mmap_lock. > > This seems fragile. If rwlocks ever become FIFO or tasklist_lock changes > type (maybe -rt kernels do it), then you could have a task holding > anon_vma lock and waiting for tasklist_lock, and another holding tasklist > lock and waiting for i_mmap_lock, and another holding i_mmap_lock and > waiting for anon_vma lock. > > CC: Nick Piggin > Signed-off-by: Wu Fengguang Acked-by: Rik van Riel -- All rights reversed.