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 AABCE4FDE57; Thu, 17 Sep 2026 16:52:55 +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=1789663977; cv=none; b=dDCCpOmyQHXPSyw3mEzX/XMmuWxtFWMQcR5msA0JkYpycJfO3igE5a8NVGvteiHrgNz5t0hxCCJe9rIT8luQsZrPd9PzJgYJ4HzM7B0z2pKzNARSz2WoozsVdz7g743vxg3Xj1UPdJmYd15/t/H9U/57KotH0D2GqXNymS+Jf1w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789663977; c=relaxed/simple; bh=hfjPCF5ZW5pBH8PYfv2eaWHlJh1728pAaeKqWtrVRRM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=s4jpBDLlcXMpqlTOmJGkSs7sSpbJcsKCMNOgeYeuTa/+qllVyXfVYVgTXusC4yr8e4JKoAOCYJrQ8OV3KtH0xD0B1vGaTQo6EJA4LLewU9W1NCbrJp2HUKyfiGLAUmaAGuKyUTf9qiHzPnmzxYKhjlozxVVQCLxWNByNSXfqSGg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=w7b9Kwi7; 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="w7b9Kwi7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F0CB1F000FF; Thu, 17 Sep 2026 16:52:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789663975; bh=X2mIpNUiF5D8j1RboRAAbiqKLiTwJ4lCRCFPC4k6lZI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=w7b9Kwi7wn4nhX+ZIEr5txVyo3oAhIbgAw0jp4T3iaqKUKeT2sBhjZimSvmPnRJI5 VbrzgKD8Zeoqc5I2v+tqB9Ob7YbAsPqGV9v2G3olSQjgREETXqZCSlXdqolnAmlLFK WXxGAAxvHOBqh+FBzue+VQm755g46q57CY+5fsos= 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 6.18 0169/1250] net: bridge: remove stale rcu_barrier() in br_multicast_dev_del() Date: Thu, 17 Sep 2026 15:59:24 +0100 Message-ID: <20260917151556.672513344@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260917151551.901433442@linuxfoundation.org> References: <20260917151551.901433442@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 6.18-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 c2a5af45df204..9de9db5fa731c 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -4456,8 +4456,6 @@ 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