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 74063C00140 for ; Sat, 6 Aug 2022 00:08:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241369AbiHFAIB (ORCPT ); Fri, 5 Aug 2022 20:08:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39826 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230490AbiHFAH5 (ORCPT ); Fri, 5 Aug 2022 20:07:57 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 91A242CE32; Fri, 5 Aug 2022 17:07:56 -0700 (PDT) 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 3D9F4B82958; Sat, 6 Aug 2022 00:07:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A213CC433D7; Sat, 6 Aug 2022 00:07:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1659744474; bh=PfJfJYAbTxS2WokCLPTsBpIupwUds+UHgvCXpLuh+R0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=lC4FldhtWQsnjCMBN7iciqnBHW0kBte0m7iTQfO9pdgAESNcpbzp/CcU7vnE13h6Y h6tExZIJCH525F0pgrgd4t5gc4XiINT4bYz21VxYs5iyNHUcJK5JHfbe9UWiWssqC6 uFowiDAirlHIIqbuOXpuOVG4NkwOKvN9VbwFNq+U= Date: Fri, 5 Aug 2022 17:07:52 -0700 From: Andrew Morton To: Roman Gushchin Cc: Linus Torvalds , Kent Overstreet , mm-commits@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dave Chinner , Joe Perches Subject: Re: [GIT PULL] MM updates for 5.20-rc1 Message-Id: <20220805170752.d609551360017d60903e5e75@linux-foundation.org> In-Reply-To: References: <20220803133541.18b82ec9344ed0e8b975fe5b@linux-foundation.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 5 Aug 2022 17:04:28 -0700 Roman Gushchin wrote: > On Fri, Aug 05, 2022 at 04:32:34PM -0700, Linus Torvalds wrote: > > On Wed, Aug 3, 2022 at 1:35 PM Andrew Morton wrote: > > > > > > - memcg debug/visibility work from Roman Gushchin > > > > Well, not just memcg. > > > > There's that new CONFIG_SHRINKER_DEBUG too. > > > > Which looks like yet another "people add Kconfig options incorrectly". > > > > We don't make new features "default y" unless there's some truly > > pressing reason for it (ie "99.9% of all people will want this" or "we > > used to always compile this in, now it's optional"). > > Hi Linus! > > It actually was 'default n' in one of the earlier version of the patchset > and has been switched to 'default y' based on the following feedback from > Dave Chinner (https://lore.kernel.org/lkml/YmiWK56bOHyrr64u@rh/): > > No. The argument that "if we turn it off there's no overhead" means > one of two things: > > 1. nobody turns it on and it never gets tested and so bitrots and is > useless, or > 2. distro's all turn it on because some tool they ship or customer > they ship to wants it. > > Either way, hiding it behind a config option is not an acceptible > solution for mering poorly thought out infrastructure. > > Personally I think that the feature is not that useful for the majority > of users (this is why default was n), but it's not adding much of the > overhead, so I had no strong reasons to oppose Dave. > Cc'ing him just in case. > We should have changelogged these considerations. I've asked Joe if checkpatch can get a "default y" detector, to draw attention to this in the future.