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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id A05D2C77B7F for ; Tue, 18 Apr 2023 22:06:04 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1EE648E0003; Tue, 18 Apr 2023 18:06:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 19EBD8E0001; Tue, 18 Apr 2023 18:06:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0667C8E0003; Tue, 18 Apr 2023 18:06:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id EC00E8E0001 for ; Tue, 18 Apr 2023 18:06:03 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id B294C1A045A for ; Tue, 18 Apr 2023 22:06:03 +0000 (UTC) X-FDA: 80695895406.08.2E315A7 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf24.hostedemail.com (Postfix) with ESMTP id 02F9718000A for ; Tue, 18 Apr 2023 22:06:00 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=dxQBhdcr; dmarc=none; spf=pass (imf24.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1681855561; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=y8o7K7+tJTN9aPBv3yYC1a1uzvFwQp3mmAkVOTLA4Vc=; b=pht3uFZ5B/MIQ/3SFWxqOUZgwtMZw0M5QP/sqhoqsMtMMOFGRkHkYcj/dg+YByB937XffR 1EpRQaFFKVXFyh1xneWGqdIkctSomw7YMf8sg7P+AzywHILkH/qRn4koLMQt/aW90ov05i jd9LLEANGx8tnobsp491onxogoK4W6w= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=dxQBhdcr; dmarc=none; spf=pass (imf24.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1681855561; a=rsa-sha256; cv=none; b=OlkF6iVHT2wkkNeR4GuZVVo1d9HjZc5tM0KE4o0HgJKSOacVHDGiVu4BLlWNL2zULnfoDf YNuRMWiP9NT5vLi4YB9Wdw1Rq0npAEiUcuFscEclkeoWo3RiwPhTu4rlVwgEghhYRfhDQy Wy9EdgIaLVy5jWw1pcl2R8BgnlLAFZ8= 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 dfw.source.kernel.org (Postfix) with ESMTPS id E916D62ED1; Tue, 18 Apr 2023 22:05:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85911C433D2; Tue, 18 Apr 2023 22:05:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1681855559; bh=4TzxYQM54gPj6fAMyI3AyBzp+dk5LpFT94Xr5/gjrX0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=dxQBhdcrCQd5w9R2wn/07cf7rhZ8iADKh1CjHqyiIBLZHS/f7OVNSf/gt8KG0CR7h Oz4N9A9EESIVDc/zZIanRvYdJy6Kbh1WqoSbL45tIyDhAh0VZ2Gkw4aRGPne/24EZV EG4PhaKU8uuzDbgnkxxKnbzEtY58uWS7osG7BkGw= Date: Tue, 18 Apr 2023 15:05:57 -0700 From: Andrew Morton To: Catalin Marinas Cc: Justin Forbes , Mike Rapoport , Arnd Bergmann , Christophe Leroy , "David S. Miller" , Dinh Nguyen , Geert Uytterhoeven , Guo Ren , John Paul Adrian Glaubitz , "Kirill A. Shutemov" , Max Filippov , Michael Ellerman , Rich Felker , Russell King , Will Deacon , Yoshinori Sato , Zi Yan , linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mm@kvack.org, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org Subject: Re: [PATCH v3 02/14] arm64: drop ranges in definition of ARCH_FORCE_MAX_ORDER Message-Id: <20230418150557.ea8c87c96ec64c899c88ab08@linux-foundation.org> In-Reply-To: References: <20230325060828.2662773-1-rppt@kernel.org> <20230325060828.2662773-3-rppt@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 02F9718000A X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: rjsuozgbk9kfq3rakdueporshytskyr6 X-HE-Tag: 1681855560-626635 X-HE-Meta: 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 PqbN9772 R1Kj3pbYgUOfVpfiVc2v/u8M3Z/QV5VLVKH8NUX79wfkXPp9Ier1K0z9FuUaowe94/22FjoxV5gYAXFfINZlNejV1qklnTypfKnndNVlMsr7vk4ANKb6GtoV6q6OHlpVsNe3E8wXp3Av9Kc/aMnPkMNyWG7qY6EBhiTnNWdv6a7daAmYfvKHR7hAbUQp4O7y0ChnR/l8NL2keRDaT1htX0WFv+MydroKR1El2LJ5jFQSqyGLn/A61ntsOhWvPw7sADpL5g/k8MxhFKXDd03AF7OQmN4JQyNxbSJL3KbC0dngpA114ZJYZaROwrFahSfwCzupKkB9sX8QoERtzWyncs+vmIazn/w0g91KO2c9nnQElH67l2IAs4m0wNeY3iG86TwvpClgHpa7dOWY0mdchx6syNMG3lLyXjlLkHsAAyeQkckSoRp9tNHOBv5OBp5azx9PZvZQ2RABKHK5HwymkNvx+g8nnkIQeZgCxYCfVSitY0gg= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, 12 Apr 2023 18:27:08 +0100 Catalin Marinas wrote: > > It sounds nice in theory. In practice. EXPERT hides too much. When you > > flip expert, you expose over a 175ish new config options which are > > hidden behind EXPERT. You don't have to know what you are doing just > > with the MAX_ORDER, but a whole bunch more as well. If everyone were > > already running 10, this might be less of a problem. At least Fedora > > and RHEL are running 13 for 4K pages on aarch64. This was not some > > accidental choice, we had to carry a patch to even allow it for a > > while. If this does go in as is, we will likely just carry a patch to > > remove the "if EXPERT", but that is a bit of a disservice to users who > > might be trying to debug something else upstream, bisecting upstream > > kernels or testing a patch. In those cases, people tend to use > > pristine upstream sources without distro patches to verify, and they > > tend to use their existing configs. With this change, their MAX_ORDER > > will drop to 10 from 13 silently. That can look like a different > > issue enough to ruin a bisect or have them give bad feedback on a > > patch because it introduces a "regression" which is not a regression > > at all, but a config change they couldn't see. > > If we remove EXPERT (as prior to this patch), I'd rather keep the ranges > and avoid having to explain to people why some random MAX_ORDER doesn't > build (keeping the range would also make sense for randconfig, not sure > we got to any conclusion there). Well this doesn't seem to have got anywhere. I think I'll send the patchset into Linus for the next merge window as-is. Please let's take a look at this Kconfig presentation issue during the following -rc cycle.