From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7419E386573; Thu, 17 Sep 2026 17:51:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789667510; cv=none; b=BK6HGjX12CTH+4TSoOl2QMU+EBuxNlCKtpUfxvJQoO8HUaozN58H4ENr+VFbEB9TuoCezQ2JHOzuL/mtKwmIXkpErm1aYWnLNNOKV6BjPN/i4ugJKqVq5+5w9go3JS+GAMEDn1o92RA+z2zCiGxJSHeRUPs/cAK0ElHbuO4T9JY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789667510; c=relaxed/simple; bh=zT9nvFqkA29f7AN9unzAqW0laj4kVLKMjRhiUIvWzKU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=g1MdAfwpHrDihRXV1M8fypyZ/oLlYu8V2Uj0dSRQmvOCv6hk+wkBg/saFp5csn/njCxgzdPaVGWfFSrK/sDo0WffuG7/PhcjZ7iU4rVenPRDmk5EyEfn2HMF3+PsvE9kZIKV4YXMVWtrFUO8pp3AQ3Sm/n2syGgiPT4mw635zn0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Y4828v5z; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Y4828v5z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CDB151F000FF; Thu, 17 Sep 2026 17:51:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789667509; bh=YvM+K3mIYDshP164AiBohiS6iNF1tBBLBL+rqWkJepc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Y4828v5zF0kUgJH/708e+vABHme6wIWfZ9gh1Y4gKkpOvlj6Ukk2Vs5G6DZGoB2XZ HgO2P9fFy3uH/TgcFOjTFQtffQNMon1UVzA57KfQvuzUv36+0OctKth9A+Cii1xipx ADkLQHJ78tlBpMPk9mWYz3yika+q2bF7a06ys+OY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , Jakub Sitnicki , Ido Schimmel , Nikolay Aleksandrov , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.12 0116/1102] net: bridge: remove stale rcu_barrier() in br_multicast_dev_del() Date: Thu, 17 Sep 2026 16:00:59 +0100 Message-ID: <20260917151542.419803475@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260917151539.408551884@linuxfoundation.org> References: <20260917151539.408551884@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 25ae123db10ba9ab890b56bcdb0a4363aee8529a ] This rcu_barrier() came from a time call_rcu() calls were used in net/bridge/br_multicast.c. Now kfree_rcu() is there, we can remove this problematic rcu_barrier() which causes extreme RTNL pressure in many syzbot reports. INFO: task syz-executor:77945 is blocked on a mutex likely owned by task kworker/u1024:5:36537. task:kworker/u1024:5 state:D stack:24616 pid:36537 tgid:36537 ppid:2 task_flags:0x4208060 flags:0x00080000 last_sleep:612797637337 Workqueue: netns cleanup_net Call Trace: [] context_switch+0xf2a/0x1730 kernel/sched/core.c:6483 [] __schedule+0x1133/0x43a0 kernel/sched/core.c:8411 [] __schedule_loop kernel/sched/core.c:8514 [inline] [] schedule+0xab/0x260 kernel/sched/core.c:8529 [] schedule_timeout+0xc3/0x2b0 kernel/time/sleep_timeout.c:75 [] do_wait_for_common kernel/sched/completion.c:100 [inline] [] __wait_for_common kernel/sched/completion.c:121 [inline] [] wait_for_common kernel/sched/completion.c:132 [inline] [] wait_for_completion+0x2c7/0x5d0 kernel/sched/completion.c:153 [] rcu_barrier+0x49f/0x620 kernel/rcu/tree.c:3888 [] br_multicast_dev_del+0x303/0x350 net/bridge/br_multicast.c:4459 [] br_dev_uninit+0x1c/0x40 net/bridge/br_device.c:157 [] unregister_netdevice_many_notify+0x1c1c/0x2300 net/core/dev.c:12599 [] ops_exit_rtnl_list net/core/net_namespace.c:187 [inline] [] ops_undo_list+0x3d3/0x940 net/core/net_namespace.c:248 Signed-off-by: Eric Dumazet Reviewed-by: Jakub Sitnicki Reviewed-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20260519095540.2643318-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/bridge/br_multicast.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index dff82eb195e82..988014b143643 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -4458,8 +4458,6 @@ void br_multicast_dev_del(struct net_bridge *br) br_multicast_ctx_deinit(&br->multicast_ctx); br_multicast_gc(&deleted_head); cancel_work_sync(&br->mcast_gc_work); - - rcu_barrier(); } int br_multicast_set_router(struct net_bridge_mcast *brmctx, unsigned long val) -- 2.53.0