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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EF5D4F364BD for ; Thu, 9 Apr 2026 21:24:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DE1C06B0088; Thu, 9 Apr 2026 17:24:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DB91D6B0089; Thu, 9 Apr 2026 17:24:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CCF7F6B008A; Thu, 9 Apr 2026 17:24:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id BDCF66B0088 for ; Thu, 9 Apr 2026 17:24:46 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 5B597139D95 for ; Thu, 9 Apr 2026 21:24:46 +0000 (UTC) X-FDA: 84640296972.08.A4D106C Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf16.hostedemail.com (Postfix) with ESMTP id E1A4F180019 for ; Thu, 9 Apr 2026 21:24:43 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Mwpb7aRF; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf16.hostedemail.com: domain of luizcap@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=luizcap@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1775769884; 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=0FZgHmN/Rbigh+5tNj53A5Ca+IYqaD6SM5ykcg30XXk=; b=sb5qzY0+mdIgGKp4GuhXtmYu0JqH1pGUyBCX+u+u0NGTrEiFgQCEoYWzQBpUKJmQCDjbYi DI0heA8dZs05f1fa3Yj4QU83CO50233VS4plG3q4rcFftqsHOfKmXiBBWAKJv3A7mOQtTZ OimO5/qfsfjHZ4ZJNaoUCT9zkpanclI= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1775769884; a=rsa-sha256; cv=none; b=J0qNvPuLG9F0qbm1jzIcdXzc/nipnoO1eyEDqzzvpiS2z6bkbFw4ZTt41iWzKhcCNAxJ8z 5+2OE6Y+ixClhmgJViaW8HIJk1FbO8YigqkVvmx6PAF3UfqenBhkRkDndi09nT+oU2pDh1 4g2saWbuHe+WECp3POCCKsCf7Eu1sHM= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Mwpb7aRF; dmarc=pass (policy=quarantine) header.from=redhat.com; spf=pass (imf16.hostedemail.com: domain of luizcap@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=luizcap@redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1775769883; 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=0FZgHmN/Rbigh+5tNj53A5Ca+IYqaD6SM5ykcg30XXk=; b=Mwpb7aRFhxa8sKJkPoih+LiWbZuw85uwO1oSk0QUAj7tfeaG7jh+IC0qtyMric99XgpTR1 V+7InL5VmQy7Ev8EIRzaOp/N7hiNd6+ZVNvto2er2c0wYILDys0t5zV0qYo3RrWsOujwW0 +XdU+yZIwxLxCvnE1BwgzyZUOT3jlM0= Received: from mail-qv1-f71.google.com (mail-qv1-f71.google.com [209.85.219.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-351-1ane-i4BMVemKVXb37YcFg-1; Thu, 09 Apr 2026 17:24:41 -0400 X-MC-Unique: 1ane-i4BMVemKVXb37YcFg-1 X-Mimecast-MFC-AGG-ID: 1ane-i4BMVemKVXb37YcFg_1775769881 Received: by mail-qv1-f71.google.com with SMTP id 6a1803df08f44-8ac04b2fc4eso43606996d6.0 for ; Thu, 09 Apr 2026 14:24:41 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775769881; x=1776374681; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=0FZgHmN/Rbigh+5tNj53A5Ca+IYqaD6SM5ykcg30XXk=; b=R7kYUO1+ea+t9UgmGsIy1CLLGtperfsyopKz3xMeX5kvc3lJuqC94vNhqg6oG8h6T8 ix8Hfi0PwiD7JZtjcg/uqswQQAWx+Uex2XKmSRHNb3rVCgNKE3sc4Bx5ijTI94VuRQgu nmb0x46DCMWUW0bId3fwzwPIDSTXUievQuNJDJoCyvJF0EZ7VPeSr5K6BtcnH8qEMhKD xbPCC0a1S60dav58oFCi4YZIA7OVpkOqlV4gLyfA3BJ3QeDWg8+XP6eaCclfM8hXw44J YXapPmLxw7tcC/hCB8WJkAn3Tw0m0ZJJJWPJHhv/vqtI8PG7Q2vf3Oxno54O8iksN3CR RWGA== X-Forwarded-Encrypted: i=1; AJvYcCVDDWXUEPl8f/NXGXE9o6nXOp/K20kUuwNRmHTjn0+Y3/g9gb8A6ra2RZP3mg/jXgYx98Zw9NroCw==@kvack.org X-Gm-Message-State: AOJu0YxT3p6RzbHLxjEn4Gxv1MhVKtXlFAi6RMELCbIKKx7WT7acX9LP AcvgmRqolTHJHYHS1VukkS3ZB70xFK6y5cDoWQASEhiaOxiTCdoEg43q5YkZmP9cJ6IZreBuvc2 ApknRuG0hHh1z7ELRo8Cc+w732kRq3kMFK9ly2ZRkmXj70Ki5h3Yi X-Gm-Gg: AeBDiev57SZCVi0JHaL7sIpf6GYf8B+vbS9J1TCW9BkqAtkEjEczp6FwM7EoUhJpVO3 TqUwDyso2gZOjsorwVMlLKxqdIyCnkZTb2lZGf9SWi23uickDiykdn4eNIC5KoE190tO6cgMRiP yIWAATkT553/osTRAh9Terf/7ldRFNTqxJTESc8gfbl/hHB4sexcm8126qFEoNjfa5l8JaOlAiy ywScQyXuszKEqAccmbs8t6GoHqbQmzgu1jMVjakXe/djhAvXm3sDGN6ArtHbbTYKZq/h4/2hsd9 wgWnPRwKbCtBFR7SISYrf5HhYiqdBX5ahfpXW2qsjj01/j2LxyIc/U1iQa7tstKaI1+6jCjzp2t 50psXO7KC8ZFC9S6GW1yYFONEW6di1sCrzQxNT/kv8veDqhlPAiMLquz5jSPcIVZQn9BEpdEkPJ 5ean9bSUMfFyZtDL8= X-Received: by 2002:a0c:e017:0:b0:8a0:f8b7:3920 with SMTP id 6a1803df08f44-8ac8620da18mr5916056d6.42.1775769881319; Thu, 09 Apr 2026 14:24:41 -0700 (PDT) X-Received: by 2002:a0c:e017:0:b0:8a0:f8b7:3920 with SMTP id 6a1803df08f44-8ac8620da18mr5915806d6.42.1775769880857; Thu, 09 Apr 2026 14:24:40 -0700 (PDT) Received: from [192.168.2.110] (bras-base-aylmpq0104w-grc-53-69-159-169-238.dsl.bell.ca. [69.159.169.238]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8ac84c45944sm6173456d6.24.2026.04.09.14.24.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 09 Apr 2026 14:24:40 -0700 (PDT) Message-ID: <4f8f3e44-7d5b-4b8a-baeb-f42fb3e8a074@redhat.com> Date: Thu, 9 Apr 2026 17:24:39 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 10/10] mm: thp: x86: cleanup PSE feature bit usage To: Dave Hansen , Zi Yan Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, david@kernel.org, baolin.wang@linux.alibaba.com, ryan.roberts@arm.com, akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov References: <16fe2db0becab98db70f53e4ce1422450a9f40ee.1775679721.git.luizcap@redhat.com> <631bceef-d32b-475f-9d1a-644593aceddc@intel.com> From: Luiz Capitulino In-Reply-To: <631bceef-d32b-475f-9d1a-644593aceddc@intel.com> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: H6iqc2vOmQBvWEV75snhHijGtHi_lMMrg270VWoMWoo_1775769881 X-Mimecast-Originator: redhat.com Content-Language: en-US, en-CA Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: E1A4F180019 X-Stat-Signature: 99xpksbh7qfdzc9bug396syfq3fnti1h X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1775769883-956114 X-HE-Meta: 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 LrSs7eMa Y+z6w9YjYmTW0CwWwiKbEqOfei5OVGeyISBopbLlmPbFyPMgNlzZS7qY3M4SmmWo5iQwscxEv0BBozLyzH5JFrRwkiHPg67+/x09h9RnKGfB/AzBI9GimwhmnnDwZRlrhuJatlcOob/IuefADxuLA2DsWluPl16IGT6yUaIviWmfpGLcA1V/HXpCK3mOvcQflmVXpLbvfkNpvlGYvrZjmp9msLbArkr/68E2TzC5KiN8vIInUTA8kMuVM0++sT9+T12oz3KmKBp0Hso77kd9IznfHEoleRILDk6hyW37fWvGIS6Bhcc3XP5stOdI5sm9bABs4WA0W/pI3dWHIpgdRReyhNM9xVPOm0nWfQ82HJyRoyZgy0ld1s+/ZrekrLAS9OoGF+3EIhaMGm1VuDsElLW4C5FD1hKoPhys+B8PXRoEZ/Q4hbr4ysYWhcw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026-04-09 16:10, Dave Hansen wrote: > On 4/9/26 08:57, Zi Yan wrote: >> Historically, THP support on x86 checked the PSE feature bit to enable >> THP. On 64-bit, this check is redundant since PSE is always enabled by >> default for compatibility. > > What do you mean by "PSE is always enabled by default"? > > A hypervisor is completely free to not enumerate PSE support to a guest. > Any kernel can disable PSE with clearcpuid=3 on the command-line. PSE is > also disabled for at least one erratum (which I think includes some > 64-bit CPUs). You're right, I was wrong to assume that PSE could be ignored on 64-bit. Thanks for taking the time to show it. I'll drop this patch for v4. > > Here's a snippet in a 64-bit VM of /proc/cpuinfo on a normal boot: > > DirectMap4k: 83836 kB > DirectMap2M: 1939456 kB > DirectMap1G: 1048576 kB > > and with clearcpuid=3: > > DirectMap4k: 3071868 kB > DirectMap2M: 0 kB > > Just to show that it's possible. > > So perhaps I'm reading into the changelog too much, but this doesn't > quite seem right to me. >