From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 96C1AC433DB for ; Tue, 30 Mar 2021 12:00:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 59E6661998 for ; Tue, 30 Mar 2021 12:00:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231782AbhC3L7r (ORCPT ); Tue, 30 Mar 2021 07:59:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41098 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231812AbhC3L7h (ORCPT ); Tue, 30 Mar 2021 07:59:37 -0400 Received: from mail-wr1-x42a.google.com (mail-wr1-x42a.google.com [IPv6:2a00:1450:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61965C061574; Tue, 30 Mar 2021 04:59:37 -0700 (PDT) Received: by mail-wr1-x42a.google.com with SMTP id c8so15947962wrq.11; Tue, 30 Mar 2021 04:59:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=U/4TeLcM1UNsh9OCgocN0tnCoz1dv6AKljeqZVGsdkE=; b=nwTyc7QEJdlUs/TfyvLtXvJqn930gAyt7rNHkJJCsr1A6x8Sgj26LWdvwSYyy0bvIW t7vMfAAGkkNnq6YeV/uWjFBhdsM9/602iP5QO3QX28NtPRuc1OdMjbhm2IQMiPMdzLib NkHdl7Ud2tkWmlPz4SEsHf9GOMJqVatpaTe8qV7rvxtG8uHk77xdm+wQzPkVXzkmce0y sxe6JtQQe+0scCA1VxWjjyVvxdtpP7W8dW3Z4jqy+Dl7PjyG9va1zYQq0k1hjobowXUN R0e8d5ICG/MnXUaMaUFyiicFl7p53aV6FebCCwWMlncuB5URZ4K8sWoelmenq3mNBoLo 0pVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=U/4TeLcM1UNsh9OCgocN0tnCoz1dv6AKljeqZVGsdkE=; b=uFKq/+D1d3G0DBfEBpmF6OeB8Cbfvbe0hsasBjujt8QaZr+5WLUvig77PbaFK5Vhhk lXcPFYxmZV4cPK5li8s0GlBH/WxDlidsE3X4SSGjJyOuB7u/Lgl+bg+pAobvzcbrPMwQ nTamr/RoqsOKu3vHhvpReXL7I4RwqvVuR1cCCoOyldFLN9L3/UykJ0GJLz+3Nvy/3lQG kUnz6QBpTPfAwJcpN3uFhyzfat/CMLPB5d8Vi09qajB+v0Xr0Vm0YpYsbQOgWmTYQWBd +Fn6rbL3+LzY+X6y9D2sl7AWHIZ69cbvcqTz4S11fHHVESSMwyMoPbKeIBOIblCcHng2 wuQw== X-Gm-Message-State: AOAM5307Y64JdTmMBKBtMy3KX9kOnKDQPUOAXz8JYj7065yXQj2FS45D ZFpy2/Shl5O5W9eTxgkTCoo= X-Google-Smtp-Source: ABdhPJy+WBqRR0bXmhglug/JD2jqX5Bsqg4lVGpV3HCUSVz3NdUFyAxn8IkLNCPuofhIS1/1avRGUA== X-Received: by 2002:adf:dd47:: with SMTP id u7mr33765469wrm.13.1617105576189; Tue, 30 Mar 2021 04:59:36 -0700 (PDT) Received: from [192.168.1.101] ([37.167.251.74]) by smtp.gmail.com with ESMTPSA id x11sm4424978wme.9.2021.03.30.04.59.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Mar 2021 04:59:35 -0700 (PDT) Subject: Re: [PATCH net-next v3 7/7] mld: add mc_lock for protecting per-interface mld data To: Taehee Yoo , netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org Cc: jwi@linux.ibm.com, kgraul@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, mareklindner@neomailbox.ch, sw@simonwunderlich.de, a@unstable.cc, sven@narfation.org, yoshfuji@linux-ipv6.org, dsahern@kernel.org, linux-s390@vger.kernel.org, b.a.t.m.a.n@lists.open-mesh.org References: <20210325161657.10517-1-ap420073@gmail.com> <20210325161657.10517-8-ap420073@gmail.com> From: Eric Dumazet Message-ID: Date: Tue, 30 Mar 2021 13:59:32 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210325161657.10517-8-ap420073@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 3/25/21 5:16 PM, Taehee Yoo wrote: > The purpose of this lock is to avoid a bottleneck in the query/report > event handler logic. > > By previous patches, almost all mld data is protected by RTNL. > So, the query and report event handler, which is data path logic > acquires RTNL too. Therefore if a lot of query and report events > are received, it uses RTNL for a long time. > So it makes the control-plane bottleneck because of using RTNL. > In order to avoid this bottleneck, mc_lock is added. > > mc_lock protect only per-interface mld data and per-interface mld > data is used in the query/report event handler logic. > So, no longer rtnl_lock is needed in the query/report event handler logic. > Therefore bottleneck will be disappeared by mc_lock. > What testsuite have you run exactly to validate this monster patch ? Have you used CONFIG_LOCKDEP=y / CONFIG_DEBUG_ATOMIC_SLEEP=y ? > Suggested-by: Cong Wang > Signed-off-by: Taehee Yoo [...] > /* > - * device multicast group del > + * device multicast group del > */ > int __ipv6_dev_mc_dec(struct inet6_dev *idev, const struct in6_addr *addr) > { > @@ -943,8 +967,9 @@ int __ipv6_dev_mc_dec(struct inet6_dev *idev, const struct in6_addr *addr) > > ASSERT_RTNL(); > > + mutex_lock(&idev->mc_lock); > for (map = &idev->mc_list; > - (ma = rtnl_dereference(*map)); > + (ma = mc_dereference(*map, idev)); > map = &ma->next) { > if (ipv6_addr_equal(&ma->mca_addr, addr)) { > if (--ma->mca_users == 0) { This can be called with rcu_bh held, thus : BUG: sleeping function called from invalid context at kernel/locking/mutex.c:928 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 4624, name: kworker/1:2 4 locks held by kworker/1:2/4624: #0: ffff88802135d138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff88802135d138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] #0: ffff88802135d138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] #0: ffff88802135d138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:616 [inline] #0: ffff88802135d138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ffff88802135d138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2246 #1: ffffc90009adfda8 ((addr_chk_work).work){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2250 #2: ffffffff8d66d328 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4572 #3: ffffffff8bf74300 (rcu_read_lock_bh){....}-{1:2}, at: addrconf_verify_rtnl+0x2b/0x1150 net/ipv6/addrconf.c:4459 Preemption disabled at: [] local_bh_disable include/linux/bottom_half.h:19 [inline] [] rcu_read_lock_bh include/linux/rcupdate.h:727 [inline] [] addrconf_verify_rtnl+0x41/0x1150 net/ipv6/addrconf.c:4461 CPU: 1 PID: 4624 Comm: kworker/1:2 Not tainted 5.12.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: ipv6_addrconf addrconf_verify_work Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 ___might_sleep.cold+0x1f1/0x237 kernel/sched/core.c:8328 __mutex_lock_common kernel/locking/mutex.c:928 [inline] __mutex_lock+0xa9/0x1120 kernel/locking/mutex.c:1096 __ipv6_dev_mc_dec+0x5f/0x340 net/ipv6/mcast.c:970 addrconf_leave_solict net/ipv6/addrconf.c:2182 [inline] addrconf_leave_solict net/ipv6/addrconf.c:2174 [inline] __ipv6_ifa_notify+0x5b6/0xa90 net/ipv6/addrconf.c:6077 ipv6_ifa_notify net/ipv6/addrconf.c:6100 [inline] ipv6_del_addr+0x463/0xae0 net/ipv6/addrconf.c:1294 addrconf_verify_rtnl+0xd59/0x1150 net/ipv6/addrconf.c:4488 addrconf_verify_work+0xf/0x20 net/ipv6/addrconf.c:4573 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294