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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8FEE6C433EF for ; Fri, 22 Jul 2022 21:10:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229760AbiGVVKN (ORCPT ); Fri, 22 Jul 2022 17:10:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229572AbiGVVKL (ORCPT ); Fri, 22 Jul 2022 17:10:11 -0400 Received: from mail-ej1-x62e.google.com (mail-ej1-x62e.google.com [IPv6:2a00:1450:4864:20::62e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 86565115C for ; Fri, 22 Jul 2022 14:10:09 -0700 (PDT) Received: by mail-ej1-x62e.google.com with SMTP id j22so10593777ejs.2 for ; Fri, 22 Jul 2022 14:10:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=C9kAKBr0M6kI73XVSIvwsHYKjO3S+2hBFzJARdNfeqA=; b=R0WCcp5TCQ5Ph8BL2j7d7B1kLjuBrkS+2jDqu/D+xiSTwdM8EqWmUEsgA24X82dLpc JdV0de7BOgrO0GA81evbaOlpMJoePnUZ6NjXFtzAfVcJyb7X6zhLNnB/mCeOLVmFza56 ldtek+1ZW2ozxgpmtk0a8GpRPydrlmrGm6068/smLGBAFz1g1vp8fUMJIEOn2VM+9YMc Hw6z9M67Qtm/xgsyWqYfprEHnJtaakJdxUex3PRhjAbYuzgb39i0Mt8kG0/4zx1yNSuZ J2ewm0diup4xFkMLw1Bvzu10i//vaetBXbqktjEUIx3JsxnwCXVAq3eEQ66/BPVxJIkg HBsQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=C9kAKBr0M6kI73XVSIvwsHYKjO3S+2hBFzJARdNfeqA=; b=3XPwnreho7YDMuy2EfMvAOjsAl2DitxI9ZBKks+TsFxyoFfyfK3a4DyC+G8G8Paljg CDFTtiB9L7Gg8dpJlKVuGoUP6GFOS4u0G0z4zQtdJCuWpiO211H8FzoLeoJBcaE/cj5H blTmKR6d1DFvQ8wuamYEoMSljv7ky6KEx85tPn5ofsOxuvdWg8ppBrHhKAkhSBv2Abf8 UYdhc9I73kAxzSPOPUGDpCLIS+xBHN3zizHJrPJ3Q0oeIC0V+46O3MOno2IB/Ab3a6R9 V/07HG9r2sIKIoM1SPbR5PhhHPPYBjMT2ZmAxRzDouC3nKNcxxyAtPIK746/SSp7qSNS PsVg== X-Gm-Message-State: AJIora/18NSPvnFJP6kmtvWkneAokBfHeYgbxUnG+It8NiC6d6W1Kyrl f8HEyi0Hi2xE7iYe07b2HGM= X-Google-Smtp-Source: AGRyM1ti7qaTJvVXC0/iNE6mqrI8v9U2pw2ooBOm+f0pxEz5qMhPZzp9iDuTgOGDq59WP8i9r4Sn/A== X-Received: by 2002:a17:907:734a:b0:72b:7c72:e6b3 with SMTP id dq10-20020a170907734a00b0072b7c72e6b3mr1332610ejc.608.1658524207950; Fri, 22 Jul 2022 14:10:07 -0700 (PDT) Received: from skbuf ([188.25.231.115]) by smtp.gmail.com with ESMTPSA id 4-20020a170906308400b0072f9dc2c246sm1984736ejv.133.2022.07.22.14.10.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Jul 2022 14:10:07 -0700 (PDT) Date: Sat, 23 Jul 2022 00:10:05 +0300 From: Vladimir Oltean To: Eric Dumazet Cc: "David S . Miller" , Jakub Kicinski , Paolo Abeni , netdev , Eric Dumazet Subject: Re: [PATCH v2 net-next 08/19] ipmr: do not acquire mrt_lock while calling ip_mr_forward() Message-ID: <20220722211005.p2pfvy4qwdvolxi3@skbuf> References: <20220623043449.1217288-1-edumazet@google.com> <20220623043449.1217288-9-edumazet@google.com> <20220722193432.zdcnnxyigq2yozok@skbuf> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Jul 22, 2022 at 10:37:24PM +0200, Eric Dumazet wrote: > Thanks for the report. > > I guess there are multiple ways to solve this issue, one being: > > diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c > index 73651d17e51f31c8755da6ac3c1c2763a99b1117..1c288a7b60132365c072874d1f811b70679a2bcb > 100644 > --- a/net/ipv4/ipmr.c > +++ b/net/ipv4/ipmr.c > @@ -1004,7 +1004,9 @@ static void ipmr_cache_resolve(struct net *net, > struct mr_table *mrt, > > rtnl_unicast(skb, net, NETLINK_CB(skb).portid); > } else { > + rcu_read_lock(); > ip_mr_forward(net, mrt, skb->dev, skb, c, 0); > + rcu_read_unlock(); > } > } > } > @@ -1933,7 +1935,7 @@ static int ipmr_find_vif(const struct mr_table > *mrt, struct net_device *dev) > } > > /* "local" means that we should preserve one skb (for local delivery) */ > -/* Called uner rcu_read_lock() */ > +/* Called under rcu_read_lock() */ > static void ip_mr_forward(struct net *net, struct mr_table *mrt, > struct net_device *dev, struct sk_buff *skb, > struct mfc_cache *c, int local) It sure makes lockdep stop complaining... I just noticed that we appear to have the same problem with the equivalent call path for ipv6: ip6mr_mfc_add -> ip6mr_cache_resolve -> ip6_mr_forward, although I don't have smcroute or the kernel configured for any IPv6 multicast routes right now, so I can't say for sure.