From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262970AbVCJSze (ORCPT ); Thu, 10 Mar 2005 13:55:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262911AbVCJSqU (ORCPT ); Thu, 10 Mar 2005 13:46:20 -0500 Received: from fire.osdl.org ([65.172.181.4]:45966 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S262863AbVCJSid (ORCPT ); Thu, 10 Mar 2005 13:38:33 -0500 Date: Thu, 10 Mar 2005 10:40:25 -0800 (PST) From: Linus Torvalds To: Robin Holt , Andrew Morton cc: Kernel Mailing List Subject: Re: [PATCH] AB-BA deadlock between uidhash_lock and tasklist_lock. In-Reply-To: <20050310123714.GA22068@attica.americas.sgi.com> Message-ID: References: <20050310123714.GA22068@attica.americas.sgi.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 10 Mar 2005, Robin Holt wrote: > > reparent_to_init() does write_lock_irq(&tasklist_lock) then calls > switch_uid() which calls free_uid() which grabs the uidhash_lock. > > Independent of that, we have seen a different cpu call free_uid as a > result of sys_wait4 and, immediately after acquiring the uidhash_lock, > receive a timer interrupt which eventually leads to an attempt to grab > the tasklist_lock. Hmm.. We fixed this already, and the current tree doesn't have this problem (and the fix was much simpler: just move "switch_uid()" to outside the tasklist_lock. That fix was done late december last year (current BK revision: 1.1938.446.38), and I really think your patch is stale. Please double-check, Linus