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 272D4C83F21 for ; Tue, 15 Jul 2025 14:17:01 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A11FA6B00B3; Tue, 15 Jul 2025 10:17:00 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 99C436B00B4; Tue, 15 Jul 2025 10:17:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8B1DF6B00B6; Tue, 15 Jul 2025 10:17:00 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 7876D6B00B3 for ; Tue, 15 Jul 2025 10:17:00 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 229431404A4 for ; Tue, 15 Jul 2025 14:17:00 +0000 (UTC) X-FDA: 83666700600.24.AD0AA3F Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf21.hostedemail.com (Postfix) with ESMTP id A8AA31C0013 for ; Tue, 15 Jul 2025 14:16:57 +0000 (UTC) Authentication-Results: imf21.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=VITNRKNa; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf21.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 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=1752589017; 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=xtUFd8jIZdacMgVpErwt3tqjgeqdKXPmgyL5wbxQy4k=; b=lomzkXtkP4gPaooXk5wEN+wa7KiI+DrIMk1H8ZXlDe+sSpG4KUl0woPmSzFkey9NNrOvTO XucwEmEShS6cALFxs94+S4Ek2VvUj2j48aCHMHwu0tXgOX1NDsj7EcIqAQThPMkd9dBjkF tviLXyYoQbOnLiLyD929+pzw3fsv9yE= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1752589017; a=rsa-sha256; cv=none; b=0b4q1tEzmmoQNoUtwkhKCjBSAqKXAn8g/sJ/KJMHdh2yYej3x1ggC5MVKt3l00TIqM4spk Izf7G7pZl8/c11QCCiowskZtacgqDiTqLV/LfEbBoUTLGvRHAa6dnaICWjOBuaDZUowSj6 Jpu2sV0YrAtuBUuKLqXjxtQaRAagwVg= ARC-Authentication-Results: i=1; imf21.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=VITNRKNa; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf21.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1752589017; 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=xtUFd8jIZdacMgVpErwt3tqjgeqdKXPmgyL5wbxQy4k=; b=VITNRKNasTTP2dM/MJPphPme3jTQ6t7w/jxlN/4CbgMSvKQ/RGNwFZpgz6n9pOGeweqIbx kyekibJHAPz0qgMwqFD1BwEOnyGpGF0jsvwultfDxtzfLW6gnHI9Xm2MHY+JkrVNtqnisr FV+ibs8Gla2iRtADwJo5JMlIgwTsJYw= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-378-MKEVu4MwPyiyYxP6VUU5_Q-1; Tue, 15 Jul 2025 10:16:51 -0400 X-MC-Unique: MKEVu4MwPyiyYxP6VUU5_Q-1 X-Mimecast-MFC-AGG-ID: MKEVu4MwPyiyYxP6VUU5_Q_1752589011 Received: by mail-wr1-f71.google.com with SMTP id ffacd0b85a97d-3a4eec544c6so2498989f8f.0 for ; Tue, 15 Jul 2025 07:16:51 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752589011; x=1753193811; h=content-transfer-encoding:in-reply-to:organization:content-language :from:references:cc:to:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=xtUFd8jIZdacMgVpErwt3tqjgeqdKXPmgyL5wbxQy4k=; b=RqI2FR6B+UaMCiq9BF5XC8Mttd2yBP1EcjkNxLrGHcdMW+a9KnLIX7E2F41z5VKf3W xJZentNYJJGUykbcVhV3xsiCeu2yf1ykNt27FzomSUq7LCGCvTtfh5YPRM0QVks7XeiX nbPBmqD489YMees9Xi8yy5Znx4Uomx4ZLgD6UTsn6PhnSjZZ52yPUNOyuwt6paNncOlu f3+5SzModmmeIaXg7OHRNcDQNbajAAxLgYzfFQi3LRhrNbfoS/TEjdQ/gU1FMzxDix7r MzOoDst16h8w/7fqKAo9OCMXouO+UJDHLwQlTbPUTu6/bywmqcJhZq5d0vu63Xn0qSDC hPQQ== X-Forwarded-Encrypted: i=1; AJvYcCVZh8KqnIEV+cZdVcQgcsnYqoWwHR9SAnjdyuwsV99AI7GS9uHO8eLmI8/OEWVKZd39WhWO4HuHdA==@kvack.org X-Gm-Message-State: AOJu0Yxo6UjINQ1j7o70Zh6kBpeAz3v8jtT09oZ0Pu5Wfe6Gj5hKgtNp 8I4X3dxef9Mg4YkLmARq4AbQFCGjkO00PDn4CCYw+AYva/7mCMr/1H6ndIgpLHhR2W+5zir9E/3 x5scVrh94lrnzC99sgzFQgyLVmpnoBfAbzuX7RzpRjnOkkbgD7H9vXXIAD47Ix1I= X-Gm-Gg: ASbGncshFnCZ7otZOf3ZtTeWYmJJhVPFR3ttWjYkAHwO64poA87VgB4MeeT7ISXmQXb lqLW4Fa25jJ7tXnp9gZ0N3jffAP5LUq+rlUXVn7LCT+EtaXksRH9dWyYAkdudtZa8JyP+3mk/uL 2rxCQK17stpU3gZ786jdhS/JtK1seyLr7JpE3W9ofwVEV/CtgNeMspSlywrNO2XuJKtpsSwe2Q4 RNdpIj6r7zzCAC3KVUQ+np6ESP8vR8JBw54WSFspO1ByAZ4CTeBffgy/XBEYAms87nAoKPQ13R9 Sa4k1ho9kE280t020j4Spo/KQ6EacIrClW62TxK+pwfM4VLqe9pvxT7MG2vss6sEXPIgCdCQngz QI4zqQhvAvyGw1K1JnuGphYI4Q0L5x3OXVT8LACr3hKEbS2C6Jlm6rH4hFcKVG2Mm/fE= X-Received: by 2002:a05:6000:2283:b0:3a5:8600:7cff with SMTP id ffacd0b85a97d-3b5f1875938mr14092622f8f.1.1752589008389; Tue, 15 Jul 2025 07:16:48 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGtF3aNyi3pbj6yCkk1zAFYxYfd7ezRbzUP3crF9cjiRso9uL/U1MBxt8As/NbiPD2fcAEmzQ== X-Received: by 2002:a05:6000:2283:b0:3a5:8600:7cff with SMTP id ffacd0b85a97d-3b5f1875938mr14092465f8f.1.1752589006625; Tue, 15 Jul 2025 07:16:46 -0700 (PDT) Received: from ?IPV6:2003:d8:2f28:4900:2c24:4e20:1f21:9fbd? (p200300d82f2849002c244e201f219fbd.dip0.t-ipconnect.de. [2003:d8:2f28:4900:2c24:4e20:1f21:9fbd]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3b5e8bd1a2bsm15527533f8f.14.2025.07.15.07.16.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Jul 2025 07:16:46 -0700 (PDT) Message-ID: Date: Tue, 15 Jul 2025 16:16:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 0/5] add static PMD zero page support To: Lorenzo Stoakes Cc: Pankaj Raghav , Zi Yan , Suren Baghdasaryan , Ryan Roberts , Baolin Wang , Borislav Petkov , Ingo Molnar , "H . Peter Anvin" , Vlastimil Babka , Mike Rapoport , Dave Hansen , Michal Hocko , Andrew Morton , Thomas Gleixner , Nico Pache , Dev Jain , "Liam R . Howlett" , Jens Axboe , linux-kernel@vger.kernel.org, willy@infradead.org, linux-mm@kvack.org, x86@kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Darrick J . Wong" , mcgrof@kernel.org, gost.dev@samsung.com, hch@lst.de, Pankaj Raghav References: <20250707142319.319642-1-kernel@pankajraghav.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: f7Nn4K5V1qcYo_A8tukMhOrQwlSh0bk11crHPwAPDkg_1752589011 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: yxa3mo8ucqek1dyg3ntir43azn1c1mto X-Rspamd-Queue-Id: A8AA31C0013 X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1752589017-21771 X-HE-Meta: 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 QDoddqXR 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 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: List-Subscribe: List-Unsubscribe: On 15.07.25 16:12, Lorenzo Stoakes wrote: > On Tue, Jul 15, 2025 at 04:06:29PM +0200, David Hildenbrand wrote: >> I think at some point we discussed "when does the PMD-sized zeropage make >> *any* sense on these weird arch configs" (512MiB on arm64 64bit) >> >> No idea who wants to waste half a gig on that at runtime either. > > Yeah this is a problem we _really_ need to solve. But obviously somewhat out of > scope here. > >> >> But yeah, we should let the arch code opt in whether it wants it or not (in >> particular, maybe only on arm64 with CONFIG_PAGE_SIZE_4K) > > I don't think this should be an ARCH_HAS_xxx. > > Because that's saying 'this architecture has X', this isn't architecture > scope. > > I suppose PMDs may vary in terms of how huge they are regardless of page > table size actually. > > So maybe the best solution is a semantic one - just rename this to > ARCH_WANT_STATIC_PMD_ZERO_PAGE > > And then put the page size selector in the arch code. > > For example in arm64 we have: > > select ARCH_WANT_HUGE_PMD_SHARE if ARM64_4K_PAGES || (ARM64_16K_PAGES && !ARM64_VA_BITS_36) > > So doing something similar here like: > > select ARCH_WANT_STATIC_PMD_ZERO_PAGE if ARM64_4K_PAGES > > Would do thie job and sort everything out. Yes. -- Cheers, David / dhildenb