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 77401E784AF for ; Mon, 2 Oct 2023 08:57:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 001858D0010; Mon, 2 Oct 2023 04:57:00 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EF57A8D0001; Mon, 2 Oct 2023 04:56:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DE2D28D0010; Mon, 2 Oct 2023 04:56:59 -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 D24D68D0001 for ; Mon, 2 Oct 2023 04:56:59 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id C72B940194 for ; Mon, 2 Oct 2023 08:56:58 +0000 (UTC) X-FDA: 81299916516.15.FA33411 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf15.hostedemail.com (Postfix) with ESMTP id 9F127A0008 for ; Mon, 2 Oct 2023 08:56:56 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=CXvEsq9V; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf15.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1696237016; 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=kZolH99067fvKHUQAUHeclQlPt0YjXr+P4dEn1LOWbQ=; b=z936yDbdSBo/EPRH63WJcCR14GzoOq/phoJMtNDHcFjDd9oIyf7cKeAy0b1GWSJO2ffhri BIyAMY+RoVudhJ7kXQ4NeLkUawk0WZFBbda5TWUK+oYpoFaTHeORCDhvGLdoEurx1n2171 bPJdcfaTBhAexO2Zbr25oWJPQs6fRbg= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=CXvEsq9V; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf15.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1696237016; a=rsa-sha256; cv=none; b=6SJe5xPudQaDp6IVrXaLxYM38+JOaMUNxvMjy/n8WtM05Los11/JGZ7dPjZGJETKYuNrMA Nj59yFOAgCFvJSxqX5KRBfm5GsJ5ZnMhBZSWpA2/t69GfQtyhtWNWkvJ1LNiGrk68ao1vg HvFke4RbWLcnWlEQLS6I4jwjkh/eBko= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1696237015; h=from:from: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; bh=kZolH99067fvKHUQAUHeclQlPt0YjXr+P4dEn1LOWbQ=; b=CXvEsq9VSlASyzVd5KOmW1Bv4g1dE+A8WMIRiyLn0evRBQ66sz71RYQ+xTBPJfsFTSatHZ B6RzrNx7/XxLUzP1TqU1PPSbr00aHo51DIeBg/JhHtI3Qkr7LYtXa493fEDL2fAUcJ+Alq +vbec04xtvHN0vFwL5vg60kLd8bu8wg= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-479-UyNHGdg-OU2728IqYAXVjw-1; Mon, 02 Oct 2023 04:56:54 -0400 X-MC-Unique: UyNHGdg-OU2728IqYAXVjw-1 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-32480c0ad52so3651061f8f.0 for ; Mon, 02 Oct 2023 01:56:54 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696237013; x=1696841813; h=content-transfer-encoding:in-reply-to:organization:from:references :cc:to:content-language:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=kZolH99067fvKHUQAUHeclQlPt0YjXr+P4dEn1LOWbQ=; b=U7l47L3irC4BEzXyftfx7Cx6sPzvqi3W1sT0LUJ77rftiMFg+YlZACzjJFOKS9quMB GftVzdPp19upW1tZ/TUwYtYrc8WoMu4hS1P6uvKbrqsck8cSl1/+8R5kjC3YeyRBAbFd qGz+2jgBmlQ5jmrWLSp/pb41pHaFgI4m+G9S52li0teMt2mo5tRnU0Ic9QORamCgtnkD Dxy8hLwVp1fLhgLqOB24BVJkbqCdEVx88vm84QJJSHPU4Y+mjhUFt1T5k7ZCNRcyU9xX LuBqzZ+6GCymkIcb8FHeZFShOW+iYsK+slqYNgkjXKpP2AB3v991/ggR3ehoZ6ffeVTg +PJQ== X-Gm-Message-State: AOJu0YyDbHd2HccZcFzpLLQ6gmxeCS37xLHj0VgHaHpz7812QJoWoIZZ 1o5+oACpTN8xfTD14V7fZlrN1rU1RwN/YQNuOYIJh+95Q2orrUwr0B7IJmB3XPqKEYQa7mfzsAn tVNs5vpj5N/Y= X-Received: by 2002:a5d:668a:0:b0:321:5969:d465 with SMTP id l10-20020a5d668a000000b003215969d465mr9091192wru.65.1696237013399; Mon, 02 Oct 2023 01:56:53 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFNivYmW4PtO+ePKJDFQz9ZH3hXp+F3LiyWwZ9zsgVXl2tVW95sg/9viMCcYxcA7zlnFJjn2Q== X-Received: by 2002:a5d:668a:0:b0:321:5969:d465 with SMTP id l10-20020a5d668a000000b003215969d465mr9091177wru.65.1696237012975; Mon, 02 Oct 2023 01:56:52 -0700 (PDT) Received: from ?IPV6:2003:cb:c735:f200:cb49:cb8f:88fc:9446? (p200300cbc735f200cb49cb8f88fc9446.dip0.t-ipconnect.de. [2003:cb:c735:f200:cb49:cb8f:88fc:9446]) by smtp.gmail.com with ESMTPSA id 11-20020a056000156b00b0032485046055sm9783325wrz.5.2023.10.02.01.56.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Oct 2023 01:56:52 -0700 (PDT) Message-ID: Date: Mon, 2 Oct 2023 10:56:51 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 Subject: Re: [PATCH v4 2/2] mm: Init page count in reserve_bootmem_region when MEMINIT_EARLY To: Mike Rapoport , Yajun Deng Cc: akpm@linux-foundation.org, mike.kravetz@oracle.com, muchun.song@linux.dev, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230928083302.386202-1-yajun.deng@linux.dev> <20230928083302.386202-3-yajun.deng@linux.dev> <20230929083018.GU3303@kernel.org> <20230929100252.GW3303@kernel.org> <15233624-f32e-172e-b2f6-7ca7bffbc96d@linux.dev> <20231001185934.GX3303@kernel.org> <90342474-432a-9fe3-2f11-915a04f0053f@linux.dev> <20231002084708.GZ3303@kernel.org> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20231002084708.GZ3303@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 9F127A0008 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: wb1wfo93c6bdjtfyw6qjwd3gwpthe69c X-HE-Tag: 1696237016-360348 X-HE-Meta: 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 0ZVTi5lh W+Ymtt4bofI9PFa5lKc2JFrKo1wx8S4YixXoTy+yczdmPJfEsNlVRUyGDz7g2ZudTmL9xIptIcHcyKbQ8cW2QLeVTh41Zm7iZtnCG1Vk8moCUv+jVj1pf8AlCdZnO3Oxe6SeIC1UoxgrJAI47LlB++paliovXLmEnFcaAFENButk8XZnxDMhWz/k5UT9BZF9j1tTDNqnco3Fp6M19hJoAYBhCJuLoZEvYZ5mcCLnm180rOyPfEoNBHTBdwK/92TlESKHVm/TThhJESaRJQXP6kh1mYsoqstfxSzKllgF/96rE4c6wycNDkHGIGJAwUTowoHug2/nN1Ac+X1opSZaXGlcnr0oMcI/8U7bLUiOtlZ4wd8y2m86zRAbh11oXbkP28+BsWGH8MngC3pPy/aRRIuCGHg2qfMhXK/ytqTXqe7lWyxs= 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 02.10.23 10:47, Mike Rapoport wrote: > On Mon, Oct 02, 2023 at 03:03:56PM +0800, Yajun Deng wrote: >> >> On 2023/10/2 02:59, Mike Rapoport wrote: >>> On Fri, Sep 29, 2023 at 06:27:25PM +0800, Yajun Deng wrote: >>>> On 2023/9/29 18:02, Mike Rapoport wrote: >>>>>>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >>>>>>>> index 06be8821d833..b868caabe8dc 100644 >>>>>>>> --- a/mm/page_alloc.c >>>>>>>> +++ b/mm/page_alloc.c >>>>>>>> @@ -1285,18 +1285,22 @@ void __free_pages_core(struct page *page, unsigned int order) >>>>>>>> unsigned int loop; >>>>>>>> /* >>>>>>>> - * When initializing the memmap, __init_single_page() sets the refcount >>>>>>>> - * of all pages to 1 ("allocated"/"not free"). We have to set the >>>>>>>> - * refcount of all involved pages to 0. >>>>>>>> + * When initializing the memmap, memmap_init_range sets the refcount >>>>>>>> + * of all pages to 1 ("reserved" and "free") in hotplug context. We >>>>>>>> + * have to set the refcount of all involved pages to 0. Otherwise, >>>>>>>> + * we don't do it, as reserve_bootmem_region only set the refcount on >>>>>>>> + * reserve region ("reserved") in early context. >>>>>>>> */ >>>>>>> Again, why hotplug and early init should be different? >>>>>> I will add a comment that describes it will save boot time. >>>>> But why do we need initialize struct pages differently at boot time vs >>>>> memory hotplug? >>>>> Is there a reason memory hotplug cannot have page count set to 0 just like >>>>> for pages reserved at boot time? >>>> This patch just save boot time in MEMINIT_EARLY. If someone finds out that >>>> it can save time in >>>> >>>> MEMINIT_HOTPLUG, I think it can be done in another patch later. I just >>>> keeping it in the same. >>> But it's not the same. It becomes slower after your patch and the code that >>> frees the pages for MEMINIT_EARLY and MEMINIT_HOTPLUG becomes non-uniform >>> for no apparent reason. >> >> __free_pages_core will also be called by others, such as: >> deferred_free_range, do_collection and memblock_free_late. >> >> We couldn't remove  'if (page_count(page))' even if we set page count to 0 >> when MEMINIT_HOTPLUG. > > That 'if' breaks the invariant that __free_pages_core is always called for > pages with initialized page count. Adding it may lead to subtle bugs and > random memory corruption so we don't want to add it at the first place. As long as we have to special-case memory hotplug, we know that we are always coming via generic_online_page() in that case. We could either move some logic over there, or let __free_pages_core() know what it should do. -- Cheers, David / dhildenb