Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932151AbbGHA4G (ORCPT ); Tue, 7 Jul 2015 20:56:06 -0400 Received: from ozlabs.org ([103.22.144.67]:37231 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752129AbbGHAz4 (ORCPT ); Tue, 7 Jul 2015 20:55:56 -0400 From: Rusty Russell To: Peter Zijlstra , Arthur Marsh Cc: Mathieu Desnoyers , linux-kernel@vger.kernel.org, rostedt , Oleg Nesterov , "Paul E. McKenney" Subject: Re: lock-up with module: Optimize __module_address() using a latched RB-tree In-Reply-To: <20150707221122.GU18673@twins.programming.kicks-ass.net> References: <55997889.5020101@internode.on.net> <20150706100447.GX3644@twins.programming.kicks-ass.net> <559A545A.80508@internode.on.net> <20150706103246.GY3644@twins.programming.kicks-ass.net> <559B63A2.4030601@internode.on.net> <20150707072951.GM3644@twins.programming.kicks-ass.net> <1736781680.1883.1436286785932.JavaMail.zimbra@efficios.com> <559C3371.2030704@internode.on.net> <20150707215620.GM19282@twins.programming.kicks-ass.net> <20150707221122.GU18673@twins.programming.kicks-ass.net> User-Agent: Notmuch/0.17 (http://notmuchmail.org) Emacs/24.4.1 (x86_64-pc-linux-gnu) Date: Wed, 08 Jul 2015 10:25:40 +0930 Message-ID: <87d203v56b.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1916 Lines: 55 Peter Zijlstra writes: > On Tue, Jul 07, 2015 at 11:56:20PM +0200, Peter Zijlstra wrote: >> On Wed, Jul 08, 2015 at 05:45:45AM +0930, Arthur Marsh wrote: >> > I'm not aware of any modules being loaded with --force . >> > >> > I've applied the patch, thanks! >> > >> > The resultant kernel locked up as follows: >> > >> > http://www.users.on.net/~arthur.marsh/20150708469.jpg >> >> This has "Not tainted" which would indeed rule out forced loading. So >> much for that idea :/ >> >> > http://www.users.on.net/~arthur.marsh/20150708470.jpg >> >> And that one has a bunch of NMI prints, curious those. But given Mathieu >> made them return NULL, that completely rules out the most interesting >> races. > > Could you try the below? It appears there was a spot freeing modules > that forgot to take them out of the tree. Ouch! Good catch. I'm testing that here.... Yep, "modprobe lp reset=7" (which fails to parse) three times and then oops in __mod_tree_insert. If you want to wrap that with a SOB and Reported-by/Tested-by if my compatriot acks... Thanks! Rusty. > --- > kernel/module.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/kernel/module.c b/kernel/module.c > index 3e0e19763d24..4d2b82e610e2 100644 > --- a/kernel/module.c > +++ b/kernel/module.c > @@ -3557,6 +3557,7 @@ static int load_module(struct load_info *info, const char __user *uargs, > mutex_lock(&module_mutex); > /* Unlink carefully: kallsyms could be walking list. */ > list_del_rcu(&mod->list); > + mod_tree_remove(mod); > wake_up_all(&module_wq); > /* Wait for RCU-sched synchronizing before releasing mod->list. */ > synchronize_sched(); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/