From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ido Schimmel Subject: Re: ipv6_addrconf: WARNING about suspicious RCU usage Date: Sat, 20 Jan 2018 21:19:59 +0200 Message-ID: <20180120191959.GA5010@splinter> References: <20180120133753.GA27861@splinter> <1516474143.3478.2.camel@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Cc: Heiner Kallweit , "netdev@vger.kernel.org" To: Eric Dumazet Return-path: Received: from out2-smtp.messagingengine.com ([66.111.4.26]:42565 "EHLO out2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756486AbeATTUD (ORCPT ); Sat, 20 Jan 2018 14:20:03 -0500 Content-Disposition: inline In-Reply-To: <1516474143.3478.2.camel@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On Sat, Jan 20, 2018 at 10:49:03AM -0800, Eric Dumazet wrote: > On Sat, 2018-01-20 at 15:37 +0200, Ido Schimmel wrote: > > On Sat, Jan 20, 2018 at 12:57:01PM +0100, Heiner Kallweit wrote: > > > Since some time (didn't bisect it yet) I get the following warning. > > > Is it a known issue? > > > > [...] > > > > > [86220.126999] BUG: sleeping function called from invalid context at mm/slab.h:420 > > > [86220.127041] in_atomic(): 1, irqs_disabled(): 0, pid: 1003, name: kworker/0:2 > > > [86220.127082] 4 locks held by kworker/0:2/1003: > > > [86220.127107] #0: ((wq_completion)"%s"("ipv6_addrconf")){+.+.}, at: [<00000000da8e9b73>] process_one_work+0x1de/0x680 > > > [86220.127179] #1: ((addr_chk_work).work){+.+.}, at: [<00000000da8e9b73>] process_one_work+0x1de/0x680 > > > [86220.127242] #2: (rtnl_mutex){+.+.}, at: [<00000000b06d9510>] rtnl_lock+0x12/0x20 > > > [86220.127300] #3: (rcu_read_lock_bh){....}, at: [<00000000aef52299>] addrconf_verify_rtnl+0x1e/0x510 [ipv6] > > > [86220.127414] CPU: 0 PID: 1003 Comm: kworker/0:2 Not tainted 4.15.0-rc7-next-20180110+ #7 > > > [86220.127463] Hardware name: ZOTAC ZBOX-CI321NANO/ZBOX-CI321NANO, BIOS B246P105 06/01/2015 > > > [86220.127528] Workqueue: ipv6_addrconf addrconf_verify_work [ipv6] > > > [86220.127568] Call Trace: > > > [86220.127591] dump_stack+0x70/0x9e > > > [86220.127616] ___might_sleep+0x14d/0x240 > > > [86220.127644] __might_sleep+0x45/0x80 > > > [86220.127672] kmem_cache_alloc_trace+0x53/0x250 > > > [86220.127717] ? ipv6_add_addr+0xfe/0x6e0 [ipv6] > > > [86220.127762] ipv6_add_addr+0xfe/0x6e0 [ipv6] > > > [86220.127807] ipv6_create_tempaddr+0x24d/0x430 [ipv6] > > > [86220.127854] ? ipv6_create_tempaddr+0x24d/0x430 [ipv6] > > > [86220.127903] addrconf_verify_rtnl+0x339/0x510 [ipv6] > > > [86220.127950] ? addrconf_verify_rtnl+0x339/0x510 [ipv6] > > > [86220.127998] addrconf_verify_work+0xe/0x20 [ipv6] > > > [86220.128032] process_one_work+0x258/0x680 > > > [86220.128063] worker_thread+0x35/0x3f0 > > > [86220.128091] kthread+0x124/0x140 > > > [86220.128117] ? process_one_work+0x680/0x680 > > > [86220.128146] ? kthread_create_worker_on_cpu+0x40/0x40 > > > [86220.128180] ? umh_complete+0x40/0x40 > > > [86220.128207] ? call_usermodehelper_exec_async+0x12a/0x160 > > > [86220.128243] ret_from_fork+0x4b/0x60 > > > > Can you please try attached patch (untested)? > > > > I would also/instead break rcu section. Thanks Eric, this should work. We can continue to block in ipv6_create_tempaddr(). Heiner, can you try Eric's patch instead? > > Holding RCU (and BH) for whole hash traversal is a recipe for disaster, > if we have thousands of IPv6 addresses. > > diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c > index ab99cb641b7cccdda0ad4ae553c09274d7dbc047..adda73466ae1dd0f3b700b3db5fbf3065e4d3f7f 100644 > --- a/net/ipv6/addrconf.c > +++ b/net/ipv6/addrconf.c > @@ -4356,9 +4356,11 @@ static void addrconf_verify_rtnl(void) >   spin_lock(&ifpub->lock); >   ifpub->regen_count = 0; >   spin_unlock(&ifpub->lock); > + rcu_read_unlock_bh(); >   ipv6_create_tempaddr(ifpub, ifp, true); >   in6_ifa_put(ifpub); >   in6_ifa_put(ifp); > + rcu_read_lock_bh(); >   goto restart; >   } >   } else if (time_before(ifp->tstamp + ifp->prefered_lft * HZ - regen_advance * HZ, next)) > > > >