From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794047753; b=wOI4Z9q1N8v2Hr6FAuy8dfeIjNa/y5WtaZeYJbmB6dMPrRnYq0orWFjUgw/JSD3S7GJ1 odhtkc+ub5B/FiFTBfMzdElG56mrR9Ciu1VABvVgHIpqs1zE/oG3FI765sh5gSp4dmYaA TXQh0K0qRbCdnV4ZcOZpk5Hg6tml7moYOoXUnn+oErDe6fcSzeL7yzzGltQwdrVFkiv+i Fe+K8eCUrILkeu6Q8ATM5O9xTB5YI212Ebxjz5msNmI4vtQroL9IsHQOXmmQxyECk8hrS FkLvIc5061fBoepxlEXANtVDqa/WtEwY33ig4GNB6jhDHiokNSv/hA1w7I29py9AhMg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794047753; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=tg99t07T65DYD4OxGmip//QMz09Mu/b178DCtKsjs24=; b=xbuTRF1U+DSI1raErWAwx3V+xtHxSTymvTcA684zxJ9UlKnV0OFdR9es6gi3dtY9wTZK 5JmMmBZaGsuVcPyJVBibZ8Y4KS4Z57qd2GaxtMnvHJ/F/hiFsKqxudL/SQ1ELMaEyxIV3 2cQ9flbtmHm4kvqsUZjQ0al8IZZrGSwB94gMqAwsj3sHBLP2GcdIR7goImmVvQrlLpEkE h9ihZ2acdAAFlIb2uDtfpJzwL5EBWKOhrp4qMgxxoJtNz5qId/F/XxvL51QfrlfK5PNoF 8PD5f1Qae9LNEUXi9MqNnSW6KSyUZdB4SaViRyudROKssMOfC+SQxyzhXHO5534pYog== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ScGBqKpV; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8501C606D80C for ; Sat, 7 Nov 2026 10:35:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ScGBqKpV Received: by smtp.kernel.org (Postfix) with ESMTPSA id E1EED1F008A5; Sat, 7 Nov 2026 10:35:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794047753; bh=tg99t07T65DYD4OxGmip//QMz09Mu/b178DCtKsjs24=; h=From:To:Cc:Subject:Date; b=ScGBqKpV3hPtqdsAePCR9HH5hKaeCWpM7X5hCOpfst1H5hrAuPRCxWkvkv1i277sW PgdD7IkdsYlXT3PfHUm1Nb5L7gJxYC9MacAh7L+DUY8LuLuhe/+d5P3f57xQJK7nzH VQNKEsfwkvBilWw/2UnVGERoFgcpjgi3cYvGSbwxKklVOogrpKoxvEBeNBk94LH39l RIJOXuqYyr6kcxNVznHHrUS1Y6RFPEiBiSNij4dTHrklhLo1+gqMdL1VDHJj3zPwIx pC4cFDGkzQc12M+B9BhfSu+9d/M/mKQOjxBW2xXZKD7Dw7C2OvFsuDTK0SFKLFzVOD +wOomitmSV/0g== From: Sasha Levin To: yun.zhou@windriver.com, idosch@nvidia.com, kuba@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] net: erspan: set lltx to avoid sch_direct_xmit deadlock" failed to apply to 6.6-stable tree Date: Sat, 7 Nov 2026 05:35:51 -0500 Message-ID: <20261107053551-failed-6.6-2d36ec73836e@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 2d36ec73836e83175deb467fd494c61006107e5d # git commit -s git send-email --to '' --in-reply-to '20261107053551-failed-6.6-2d36ec73836e@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 2d36ec73836e83175deb467fd494c61006107e5d Mon Sep 17 00:00:00 2001 From: Yun Zhou Date: Thu, 8 Oct 2026 17:38:24 +0800 Subject: [PATCH] net: erspan: set lltx to avoid sch_direct_xmit deadlock The ERSPAN xmit path re-enters the network stack, causing nested acquisition of _xmit_lock on the underlay device while already holding the ERSPAN device's _xmit_lock, creating an ABBA deadlock. This happens for both IPv4 ERSPAN (erspan_xmit() -> ip_tunnel_xmit()) and IPv6 ERSPAN (ip6erspan_tunnel_xmit() -> ip6_tnl_xmit()): sch_direct_xmit [lock erspan] -> erspan_xmit -> ip_tunnel_xmit -> ip_output -> __dev_queue_xmit -> sch_direct_xmit [lock underlay] sch_direct_xmit [lock erspan] -> ip6erspan_tunnel_xmit -> ip6_tnl_xmit -> ip6_output -> __dev_queue_xmit -> sch_direct_xmit [lock underlay] Set dev->lltx = true so HARD_TX_LOCK() skips the spinlock for ERSPAN. This is safe as the ERSPAN xmit path has no shared mutable state: o_seqno is atomic, TX stats are per-CPU u64_stats, dst_cache is per-CPU, and o_flags is no longer modified in the xmit path since commit 9958e69b9893 ("gre: fix ERSPAN o_flags race/corruption in xmit and fill_info"). GRETAP, the sibling device with identical xmit structure, already sets lltx. Reported-by: syzbot+9bda1b9fbb7fbdf9b62b@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=9bda1b9fbb7fbdf9b62b Fixes: 84e54fe0a5ea ("gre: introduce native tunnel support for ERSPAN") Fixes: 5a963eb61b7c ("ip6_gre: Add ERSPAN native tunnel support") Cc: stable@vger.kernel.org # 9958e69b9893 ("gre: fix ERSPAN o_flags race/corruption in xmit and fill_info") Cc: stable@vger.kernel.org Signed-off-by: Yun Zhou Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20261008093824.119453-1-yun.zhou@windriver.com Signed-off-by: Jakub Kicinski --- net/ipv4/ip_gre.c | 1 + net/ipv6/ip6_gre.c | 1 + 2 files changed, 2 insertions(+) diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c index e4878e9aa6367..149a4e83b6925 100644 --- a/net/ipv4/ip_gre.c +++ b/net/ipv4/ip_gre.c @@ -1367,6 +1367,7 @@ static int erspan_tunnel_init(struct net_device *dev) dev->features |= GRE_FEATURES; dev->hw_features |= GRE_FEATURES; dev->priv_flags |= IFF_LIVE_ADDR_CHANGE; + dev->lltx = true; netif_keep_dst(dev); return ip_tunnel_init(dev); diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index 04f7c70b7320e..3429543ec77e7 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -1864,6 +1864,7 @@ static int ip6erspan_tap_init(struct net_device *dev) dev->mtu -= 8; dev->priv_flags |= IFF_LIVE_ADDR_CHANGE; + dev->lltx = true; ip6erspan_tnl_link_config(tunnel, 1); netdev_hold(dev, &tunnel->dev_tracker, GFP_KERNEL); -- 2.53.0