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 4AA9A5349AA; Wed, 30 Sep 2026 17:51:42 +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=1790790703; cv=none; b=NZssQSlVVeH3vhUXWvO5Yktc9qmuce91mx02xhe4ZzOKReixZV/Ve8p6shIwzwk7dJABvdrwlocuW6FmUltfIB2jA5Inu1EtNYuKY6PFc0HwuVcn+yChwBI+9NoAnatuA/ntmkfT7fxDj5oGzfoRFpfcf5kVYGoxVrAAS3CWc/g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790790703; c=relaxed/simple; bh=9XSL5I7aCJBKg2cTM0s4ysRydPSkicZD7WnTL71z6SM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=s88b10kovZ/Shb7qeqtaXRJ4kEDOguKIJBqE1gOqjmVEY7BL0VAR5e3VvDdQqX5vJJpb7AwQPZMXRyl4wXmw2RNTIcFaOsFV7R0Znb6DnYkkgSmYzsfXmCUyNQUdMiVuGpVT/EWJ0qzdsVbi/3pwV8ai6wi6OyJ3Ye/dsizgunQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=PQo+XJDF; 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="PQo+XJDF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA9F21F000FF; Wed, 30 Sep 2026 17:51:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790790702; bh=02rZ275EkFm1ezQGwOFOdnV1Hl4lrOAKwv9838GMa/A=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=PQo+XJDFQxicACBeDFvJHqFd7MQSGEWU8+j5Lni9orRa30/gtZjVSgy1PXgo049He v49yf0aerWwY1ZFHXtcLE1uIgH3Xivho3wLo6nX4K80aF8dTfcP7oiA6RZLPOmErIm fRfJ8QCAOM79+FB6skkKjvKvq05HIpc7eqAttOdM= 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 5.15 045/752] net: bridge: remove stale rcu_barrier() in br_multicast_dev_del() Date: Wed, 30 Sep 2026 17:18:35 +0200 Message-ID: <20260930152359.128645984@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152358.131179731@linuxfoundation.org> References: <20260930152358.131179731@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 5.15-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 66c23203c3d3e..a91c133ce2968 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -4258,8 +4258,6 @@ 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