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 X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48B07C433E0 for ; Mon, 22 Mar 2021 19:27:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 181FA61993 for ; Mon, 22 Mar 2021 19:27:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231982AbhCVT0x (ORCPT ); Mon, 22 Mar 2021 15:26:53 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:40644 "EHLO mail.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230316AbhCVT0T (ORCPT ); Mon, 22 Mar 2021 15:26:19 -0400 Received: from localhost (unknown [IPv6:2601:601:9f00:477::3d5]) by mail.monkeyblade.net (Postfix) with ESMTPSA id 3858E4D249275; Mon, 22 Mar 2021 12:26:18 -0700 (PDT) Date: Mon, 22 Mar 2021 12:26:13 -0700 (PDT) Message-Id: <20210322.122613.1113183432857887657.davem@davemloft.net> To: dvyukov@google.com Cc: edumazet@google.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net: make unregister netdev warning timeout configurable From: David Miller In-Reply-To: <20210320142851.1328291-1-dvyukov@google.com> References: <20210320142851.1328291-1-dvyukov@google.com> X-Mailer: Mew version 6.8 on Emacs 27.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.6.2 (mail.monkeyblade.net [0.0.0.0]); Mon, 22 Mar 2021 12:26:18 -0700 (PDT) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dmitry Vyukov Date: Sat, 20 Mar 2021 15:28:51 +0100 > netdev_wait_allrefs() issues a warning if refcount does not drop to 0 > after 10 seconds. While 10 second wait generally should not happen > under normal workload in normal environment, it seems to fire falsely > very often during fuzzing and/or in qemu emulation (~10x slower). > At least it's not possible to understand if it's really a false > positive or not. Automated testing generally bumps all timeouts > to very high values to avoid flake failures. > Make the timeout configurable for automated testing systems. > Lowering the timeout may also be useful for e.g. manual bisection. > The default value matches the current behavior. > > Signed-off-by: Dmitry Vyukov > Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=211877 > Cc: netdev@vger.kernel.org > Cc: linux-kernel@vger.kernel.org I'd say a sysctl knob is much better than a compile time setting for this. That way stock kernels can be used in these testing scenerios. Thanks.