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=1794046322; b=W1AeeZZI59s098jwm0uay/1KCx5hbrsBpQMZOOSuLzR2lYwqah0AE9TMwbNWuWmamtWV YM6CfwGGSV5arlFv+TYikmChBn3hMjaG3CbNuhnsMiWJPGAsXXXyxjkfgfaMpOxzV17hM ZuHm2lJY3V0hANENNUnq9wVAfTT0GAyPLWRNbGemE/z1wKcRZM7GqzAP38Gp/5piD2FL8 oWdVqAQWg0tgnUEAgTKCrguStLgab3tixhecjk5Z/YnWYrLTx7i6gfTMT+fJ1mi7FNcSH 5yizGkBtMIvdykFDJOPrk0BnOF6hy6qrXKXMrIq62h/753Ai79kI4J5KhZUydwxDKcg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794046322; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=3wxc9ZmiLh69lk+3qFpazaiXknnUxY2PpUY8hKRsM5A=; b=TPsgQUypMh+oZz5kbUNSDyPiPCnOb+/NvJUZP10is4fe1yU0l3LyfTTivecBMQQHxu+b /sGlRTxjKdwyMGhVoSLWz39mRcAKnG6LsQ/7s31cU84XqqZbSO/UxyQYwZpmF3MbZK5i1 7zPaAFEX14sSp0sQbvMwF9o/kcm6Ek5pSgjtyziG+3f+XnyIfHf2AllGxxOjV7xuDhl1e l22N/v9WKzXFkfcKpq/5bPI/L35zijLKMK7OxQp8G9oJYZobyft8dKIOHD18wmoWa7WOt RB4M/QGHEmSbBt/OGx/IvuFjViqZQbZq6HOjA3HhQizKdv6BYBR4LbQ8ainw2fKVRNw== 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=lm0+BRUW; 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 94681606A32C for ; Sat, 7 Nov 2026 10:12:02 +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=lm0+BRUW Received: by smtp.kernel.org (Postfix) with ESMTPSA id E6E911F0089F; Sat, 7 Nov 2026 10:12:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794046322; bh=3wxc9ZmiLh69lk+3qFpazaiXknnUxY2PpUY8hKRsM5A=; h=From:To:Cc:Subject:Date; b=lm0+BRUWFjTWpNyEj/amJll4BNgI5g5c8QYwurJ7VA9l0ASghFgU78eQwT4fX4Ouo zSi+qHU9hRh9dG0jQyHyBdGQWSOFy3JFz3YUZYFzx+S0OQP0P6OuH5DuGjziQ6RTNS 44QntvzvYh6i1o5g2L3HBBw+jRy8qH6sPRyxpTDr/2V8GOre4pzqWhiAh0ehN1sQbg wQ+CazXPBM1CdZg7TBhoFYH0CP99czKomKScAbSOK6G59WCaFmz7p8g8XVBzPKuZFx mce8R3SmKYLl4Eq9LRSs7WGexC/iVC/VPz8UvVmYlgfLcYi6H4Hx6UxAvqkm2nBUAq li4KYnbNMOgAg== 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 6.18-stable tree Date: Sat, 7 Nov 2026 05:12:00 -0500 Message-ID: <20261107051200-failed-6.18-2d36ec73836e@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 6.18-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-6.18.y git checkout FETCH_HEAD git cherry-pick -x 2d36ec73836e83175deb467fd494c61006107e5d # git commit -s git send-email --to '' --in-reply-to '20261107051200-failed-6.18-2d36ec73836e@kernel.org' --subject-prefix 'PATCH 6.18.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