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 406683CB54E; Wed, 30 Sep 2026 18:47:43 +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=1790794064; cv=none; b=h0n7Cc8qRWs7fHqUBtiKRSnsn3OjPUXDWZ5eS3REdsc2PPsjasD6xUp1v4XqiCa47FFegtXStUokNXzuiLyQuf9fU+TJkCwKVH6/Kn9huGx5Ua7s5ThwaOaIRdhSOgZkoFUN6jnyMdHQHnDjiPFBPRezj02SZ5GT2x+0NY7bl8k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790794064; c=relaxed/simple; bh=8HtkqDqSgDtAJv6f2if3hSPSUJDUvdALWMGextYhKww=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TjI2ZBHfd791jVwYnMBeIpBN9Jy8q+Fuxh1rFKQbRI29dqgfIkLUXDFQ4KnfCBeTPX8vgzfZH8007qEx8wpLxkgMAHggaOgCW5Lp77YyhBUNsoYIiHajdp1LVOYQZxHdaNQ7f2VmT/R7s7TUFXwQgZhvTti5YbxFwhiKfxciYqg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=at8svDvM; 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="at8svDvM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9F1771F000FF; Wed, 30 Sep 2026 18:47:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790794063; bh=Hd5x+Mm8zSX1GFgGR/2OE2MBu0HiLXbYHEcMTByMsek=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=at8svDvMUkOoMfmDeu/wgdsKqf1cz3Hpk6Vxy9txh6doAkUKvcAw3UeB68EN2lyrG fbel2nCpI6S7SX3W773U8Cxx0AwoBWOC3FgskGphiJ/toNUlwKWEdb1TiYCtRs+K9L Dhz5paoc30c3hEtoQy1h1fJDCTMUfgIn8IAYjIP4= 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 6.6 0079/1193] net: bridge: remove stale rcu_barrier() in br_multicast_dev_del() Date: Wed, 30 Sep 2026 17:12:43 +0200 Message-ID: <20260930152436.009660264@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152434.301151190@linuxfoundation.org> References: <20260930152434.301151190@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 6.6-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 ecbd99ea2af7d..11ac945c6e29b 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -4457,8 +4457,6 @@ 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