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=-9.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 BB10EC4338F for ; Fri, 6 Aug 2021 15:36:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9D58D60EE7 for ; Fri, 6 Aug 2021 15:36:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243459AbhHFPgh (ORCPT ); Fri, 6 Aug 2021 11:36:37 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:39556 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232103AbhHFPgg (ORCPT ); Fri, 6 Aug 2021 11:36:36 -0400 Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 89DF222426; Fri, 6 Aug 2021 15:36:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1628264179; h=from:from:reply-to: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; bh=U/SzI1b8roifatTGVdNUueHB2p+u563uKTQPFj/ICfU=; b=YwLLjMqAGe5/JcIBxU4RtVAHbGmKb205bHTmlg/4lTGMQGA6tSb27yv9ep0NeY3NfIYJVM yOQhg3/PRcjZ2oo7BVKlslZtn2MWB47JBtdqAiyM3H8OdtReMQ1lgi8mJrg+XSiTghhQhQ PTJPm+3mX43KFh/cYGdyA1HBc0NttHY= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1628264179; h=from:from:reply-to: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; bh=U/SzI1b8roifatTGVdNUueHB2p+u563uKTQPFj/ICfU=; b=te7htrDx210RhQaDluHmmOYI41uNnAU3QUhHwKP5S/VsW9mThyjfJoyIKdaO+VF8om2COp ih24c70zxQxXkBCA== Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap1.suse-dmz.suse.de (Postfix) with ESMTPS id 25A9713A86; Fri, 6 Aug 2021 15:36:19 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap1.suse-dmz.suse.de with ESMTPSA id 3etuB/NWDWFUMAAAGKfGzw (envelope-from ); Fri, 06 Aug 2021 15:36:19 +0000 Subject: Re: [RFC PATCH 00/15] Make MAX_ORDER adjustable as a kernel boot time parameter. To: Zi Yan , David Hildenbrand , linux-mm@kvack.org Cc: Matthew Wilcox , "Kirill A . Shutemov" , Mike Kravetz , Michal Hocko , John Hubbard , linux-kernel@vger.kernel.org, Mike Rapoport References: <20210805190253.2795604-1-zi.yan@sent.com> From: Vlastimil Babka Message-ID: <40982106-0eee-4e62-7ce0-c4787b0afac4@suse.cz> Date: Fri, 6 Aug 2021 17:36:18 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210805190253.2795604-1-zi.yan@sent.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/5/21 9:02 PM, Zi Yan wrote: > From: Zi Yan > Patch 3 restores the pfn_valid_within() check when buddy allocator can merge > pages across memory sections. The check was removed when ARM64 gets rid of holes > in zones, but holes can appear in zones again after this patchset. To me that's most unwelcome resurrection. I kinda missed it was going away and now I can't even rejoice? I assume the systems that will be bumping max_order have a lot of memory. Are they going to have many holes? What if we just sacrificed the memory that would have a hole and don't add it to buddy at all?