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 D5CDEC433EF for ; Tue, 25 Jan 2022 02:33:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S3421067AbiAYC0F (ORCPT ); Mon, 24 Jan 2022 21:26:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56608 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244557AbiAXTsh (ORCPT ); Mon, 24 Jan 2022 14:48:37 -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 50DD3C02B8D6; Mon, 24 Jan 2022 11:23:36 -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 C60EFB810BD; Mon, 24 Jan 2022 19:23:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D666EC340E5; Mon, 24 Jan 2022 19:23:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643052213; bh=Cxrhw0mczMyhZ1QX+B6rSfeV8iyoAeiPu4kVy1aqEBY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=j9NYMuchI3L3FabQl2ozMpKyWh+hWM47Ze3vf2wXBvy+FoJYilbReAXwcAF+vU8A9 WlkPAYUZnyUFMxXHjwn9YJtZyojMirPL6NKPGSVBfG5muOZgXrvDy0qh7phTfH1VLt yS0vaVChfKh2QZPh5lvzkFxDXKTXZThEmpL4RT3o= 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 4.19 226/239] netns: add schedule point in ops_exit_list() Date: Mon, 24 Jan 2022 19:44:24 +0100 Message-Id: <20220124183950.294608115@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124183943.102762895@linuxfoundation.org> References: <20220124183943.102762895@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 @@ -149,8 +149,10 @@ 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);