From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiner Kallweit Subject: Re: ipv6_addrconf: WARNING about suspicious RCU usage Date: Sun, 21 Jan 2018 22:22:16 +0100 Message-ID: <30e8683f-eeb2-0b01-c12b-538c91ab8e93@gmail.com> References: <20180120133753.GA27861@splinter> <1516474143.3478.2.camel@gmail.com> <20180120191959.GA5010@splinter> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: "netdev@vger.kernel.org" To: Ido Schimmel , Eric Dumazet Return-path: Received: from mail-wr0-f178.google.com ([209.85.128.178]:45063 "EHLO mail-wr0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbeAUVWX (ORCPT ); Sun, 21 Jan 2018 16:22:23 -0500 Received: by mail-wr0-f178.google.com with SMTP id 16so6546233wry.12 for ; Sun, 21 Jan 2018 13:22:22 -0800 (PST) In-Reply-To: <20180120191959.GA5010@splinter> Sender: netdev-owner@vger.kernel.org List-ID: Am 20.01.2018 um 20:19 schrieb Ido Schimmel: > 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? > So far everything looks good with Eric's patch. The warning didn't show up again. >> >> 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)) >> >> >> >> >