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=1794049644; b=xVq/utZxz6G/Ao8TD/YQZ1XitEnvdPJcEwBm1gUBpiJso3BFeFjAy/EjVHrPDbDu8bbo ma4JNMbDXZjg08g+woBxIC0hiVm73MT8vaQCUx8e4TOZlUm+W3W5eLLnJTw2j2bIMyvnR jw9OVJPOpGBVr/ei+AzuFTRKJgzWuT8KwuqDq8hYObnmfW+Ilhj7dNKAZR+cLLJcESKoA ykgUSB01RXT5SYntLSh+eQ1YWt+58SpKCHnywIvSv2TZHxDzyD4TLd8Q35xtilug4R2iO B/97Vy9DEIXZQyCFn05uaZrhGG1iyAQu/I2HV/dL31rH8Tlipk4NA5KoB0fXb6VKi3w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794049644; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=e/wZL7uAIzsH7sYIBXBM3EQjzqwX0tC8n5oDX9t7y0g=; b=fehYAtWzFSAqecuOk6ztlETxrcTWvs6/veCYjC0IRFztc/aTIsoJpDG3td0TrU1cmIaL cLfaWDG2C2PK3I3TVNSI4i9dZ65MM05jfO7iCVWHMVNthHtfwvLw+Dh4vAz9tvQ9EyUtV YCV/FW7M9O7FzLrr73HFngp2QGTLGMM8wzPyuG8e4ralswH94QEA3NRBjG+GEIFNN9KlJ /9BOjmzOOMu8fW3R880ne+0xdbk3uxsBaPWAh1mPIXoojIS9VWDWCr41FSTpdgY/lRxkI z6kp8jY5GMjFA2IubCPQqvYv2Lzkd2hqIfWRZ0kvOrsfsOwYqeEj3mXf7rU/mkV8qWg== 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=Fmrb4IaJ; 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 99EF6606D808 for ; Sat, 7 Nov 2026 11:07:24 +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=Fmrb4IaJ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02A471F0089F; Sat, 7 Nov 2026 11:07:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794049644; bh=e/wZL7uAIzsH7sYIBXBM3EQjzqwX0tC8n5oDX9t7y0g=; h=From:To:Cc:Subject:Date; b=Fmrb4IaJLFa8Ou3f+FUw6mM5K7Ol347l+QbzgC72L9dS2NfCiX/+VLXfMWYdbWtO9 r+YTxzbTeKOOZvOSWg0CIebNVMdh7CZczWvAdYisv5IdWSfF8mBh3rl4MVMIWHGCvV IKFH1OQkA2N4LfkPiJuVXgAAuk+IJj1rRgFWp1xyG5IZtVGSCRvWNgLEZaETb1L1yY IZSsfhNAWp2017gf+wYCcSpDFrIJmpOT2mQ5FqEeX2y9Eenvs+rG+rixFVEgrdhygW 4lRMft/+JZnOnCbApgj6co5m4sIjbT1/RQ8F08UxyDoNX97fOpwq5ck6fCMqTLBmcr 3HzyBYepo1eOA== 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 5.15-stable tree Date: Sat, 7 Nov 2026 06:07:22 -0500 Message-ID: <20261107060722-failed-5.15-2d36ec73836e@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 5.15-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-5.15.y git checkout FETCH_HEAD git cherry-pick -x 2d36ec73836e83175deb467fd494c61006107e5d # git commit -s git send-email --to '' --in-reply-to '20261107060722-failed-5.15-2d36ec73836e@kernel.org' --subject-prefix 'PATCH 5.15.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