From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EB468C433EF for ; Mon, 24 Jan 2022 18:58:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245739AbiAXS6j (ORCPT ); Mon, 24 Jan 2022 13:58:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43142 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344435AbiAXSyk (ORCPT ); Mon, 24 Jan 2022 13:54:40 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 30BA1C06175E; Mon, 24 Jan 2022 10:53:28 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id EC80DB8121A; Mon, 24 Jan 2022 18:53:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F0944C340E5; Mon, 24 Jan 2022 18:53:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643050405; bh=Jp1D2HXeEPJRnII3/fBMon8Hpv+73Bm1AarWOZp1Gfk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Y2BmY5eP6H6QWMBaHrzR8O12LysqN1gSfdU4/UOGODfNXehAzoPSLjDDtbvjrr62d W3gqdV0ihohjwYhA/Un1IDHMBOFHkWt8FblNb2i75WKDM/or4YKEyWjZ5n2cjCiQ1m GpaKD0pajuqwF77sPMxSxBhauMtXL84rViL9sWeQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , "Eric W. Biederman" , "David S. Miller" Subject: [PATCH 4.4 107/114] netns: add schedule point in ops_exit_list() Date: Mon, 24 Jan 2022 19:43:22 +0100 Message-Id: <20220124183930.408812024@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124183927.095545464@linuxfoundation.org> References: <20220124183927.095545464@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet commit 2836615aa22de55b8fca5e32fe1b27a67cda625e upstream. When under stress, cleanup_net() can have to dismantle netns in big numbers. ops_exit_list() currently calls many helpers [1] that have no schedule point, and we can end up with soft lockups, particularly on hosts with many cpus. Even for moderate amount of netns processed by cleanup_net() this patch avoids latency spikes. [1] Some of these helpers like fib_sync_up() and fib_sync_down_dev() are very slow because net/ipv4/fib_semantics.c uses host-wide hash tables, and ifindex is used as the only input of two hash functions. ifindexes tend to be the same for all netns (lo.ifindex==1 per instance) This will be fixed in a separate patch. Fixes: 72ad937abd0a ("net: Add support for batching network namespace cleanups") Signed-off-by: Eric Dumazet Cc: Eric W. Biederman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/net_namespace.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -130,8 +130,10 @@ static void ops_exit_list(const struct p { struct net *net; if (ops->exit) { - list_for_each_entry(net, net_exit_list, exit_list) + list_for_each_entry(net, net_exit_list, exit_list) { ops->exit(net); + cond_resched(); + } } if (ops->exit_batch) ops->exit_batch(net_exit_list);