From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3E76B3C8C68 for ; Thu, 14 May 2026 12:14:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778760859; cv=none; b=blku0ckVcyNL/4xABMzw/Rbre7pYt4is4CIj46ZLg1ho5YDD6xCDV7ocj6AEAD21bleDwieFgpBChJqERLCLdtaSre6Mc8R0ZS+1VwAo2nXpG7up/RiSS6Dks6jK48XmSdVA11qs+DTDA2k6D/qeWeQLYZSFiUCXn4lkqtFFeo8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778760859; c=relaxed/simple; bh=E85W/vUpmYbWzb+oKpRl2LWoG+xexuh/wQFuJFn5+70=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Mn16KUjy/VmXzWMsT1fNU4yd7DRz/x26eFjjvJOB2MJBN5y5ftF9gQFAmjwxcwUO/KMQ7nFW8DGDDpRhzv9Q/N1ODxqm/gcgJ0RG2ZcL8tY6GwK6sFvfUPr5mhJKo+8ijLxK8sr7TyygSz0KTbGor7sc/CmTJOQUV0Hxddsk2zY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=ZV00eRmy; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ZV00eRmy" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1778760856; 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=8RnBJ1a8DxUrca0tptK0yj7QWJRhx7CVdxSVy5FH8P4=; b=ZV00eRmycjMKaY7ATx3bSfsaFSjKb6drih3r2Oobz8w95BP05W56hSeShKptg8CmeXSbJ2 8C75tFV84G8ld2bm2rzs+z8BiZbCShkre/GM0KmpCLTiuXYRjTCzbKDzuiyPOZJGKg/HEC PzT3NlzOfOgQETqIdy1SoKDyLLLd7Fg= Received: from mail-qk1-f200.google.com (mail-qk1-f200.google.com [209.85.222.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-624-CFTv_-mvPq-hB7OGdBR06Q-1; Thu, 14 May 2026 08:14:15 -0400 X-MC-Unique: CFTv_-mvPq-hB7OGdBR06Q-1 X-Mimecast-MFC-AGG-ID: CFTv_-mvPq-hB7OGdBR06Q_1778760855 Received: by mail-qk1-f200.google.com with SMTP id af79cd13be357-90f4e81b8e2so499158085a.0 for ; Thu, 14 May 2026 05:14:15 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778760855; x=1779365655; 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=8RnBJ1a8DxUrca0tptK0yj7QWJRhx7CVdxSVy5FH8P4=; b=Ud3uvNTJtO26YLxNkPKPGD8fSXfk1SD4fV4sJg6Ol/TOheoUS/7UrubuUvFDiWkNS1 YptieZLEHRX2X5Uearmt3HAaMdLFhNdLCdeZC0h68Wlfm7OCwmSHhxZ2rl5wzfSAy35v 5BtB8QUW/LgLwMeKeNZoW+aRQsdJ/Qo9lMbF8e0Fpn3SSJN9P4Phlcz90RwXtAv7ddgv A5DZ/Dvgz1QjVbEnvHcgCq/27r06OeJELCgSb3LTkHGAPm+U2Pc75nv0j/AJmLXV9GrX jBsH8oYG6Y2yAWSyXz4vQvpPf2W/BVeUbcmbF+LCpHA4X9ROUjVEAMIn/gB+m4pLRbTU r4Lg== X-Gm-Message-State: AOJu0YxokkO1KwLS5Vm7vZVsR8W4Tt0kWwus+6Awe2rND/U9OpoXM/dl AvSIXrMGFF5asC3pXoEXUsS1K1671iqmt5y9Rlo9rK8YcmQMlCKYZb1PIlPYXL6l7wzc05lwwYT EKowLE2MvKVuZZz7YjYdBhR1MVl3LqXZdkmHezbGiI35OELfrN9CG1A5NoszQmaDEww== X-Gm-Gg: Acq92OEaAkmBp5IX7T9GGpBPExJx6Yo+6sXggrljw6PCB+ZnmczOVIjMoZ1Eyt4I581 Qn6lglIou8nkU/xFV++Nb0ZWQvxXKv7wQwtqeuveHvanNgxbqF2VfG/H1RiHvAer+OpsKl4/W58 wXlrcfUpJHnTgW2qGxdN8yXgzqrCwr5uGE5eWSPLdToy0a5tAe+MChQQwGEqitmwS0DJrRF7XfQ RRUpn5NU1maGldX/WMszJ6TemlK3BqBXt4Dvd05WrJwAmxFYiVWHjn1EULrScnbFN+j6ba3Xs7j RBgi82VxZr5kghxVbG2CdpThS7VoM/XdvLCQHVKyrT/ZiA62Vg2jPRyBL3je42yBkMdW1QIoowl x3kfu5VArwpM9MTitgMl60Pf/ESDy8u4gGofn6XMQ9UsMNxfIPKqqZhxl0YqMFxYimzpbA8rth/ 7XG7oZegOH3q6K X-Received: by 2002:a05:620a:5221:b0:910:4e35:cf02 with SMTP id af79cd13be357-9104e35d43cmr604156485a.37.1778760854665; Thu, 14 May 2026 05:14:14 -0700 (PDT) X-Received: by 2002:a05:620a:5221:b0:910:4e35:cf02 with SMTP id af79cd13be357-9104e35d43cmr604148085a.37.1778760854046; Thu, 14 May 2026 05:14:14 -0700 (PDT) Received: from [192.168.2.110] (bras-base-aylmpq0104w-grc-22-70-53-202-134.dsl.bell.ca. [70.53.202.134]) by smtp.gmail.com with ESMTPSA id af79cd13be357-910ba36e638sm231744885a.9.2026.05.14.05.14.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 May 2026 05:14:13 -0700 (PDT) Message-ID: Date: Thu, 14 May 2026 08:14:12 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 0/9] mm: thp: always enable mTHP support To: Lorenzo Stoakes Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, david@kernel.org, baolin.wang@linux.alibaba.com, ziy@nvidia.com, lance.yang@linux.dev, corbet@lwn.net, tsbogend@alpha.franken.de, maddy@linux.ibm.com, mpe@ellerman.id.au, agordeev@linux.ibm.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, x86@kernel.org, dave.hansen@linux.intel.com, djbw@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, akpm@linux-foundation.org References: Content-Language: en-US, en-CA From: Luiz Capitulino In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2026-05-14 02:35, Lorenzo Stoakes wrote: > -cc my previous kernel mail > > (Minor annoying reminder to update my email to ljs@kernel.org :P) Nah, my fault. I promise I updated your email now. > > On Fri, May 01, 2026 at 03:18:42PM -0400, Luiz Capitulino wrote: >> Today, if an architecture implements has_transparent_hugepage() and the CPU >> lacks support for PMD-sized pages, the THP code disables all THP, including >> mTHP. In addition, the kernel lacks a well defined API to check for >> PMD-sized page support. It currently relies on has_transparent_hugepage() >> and thp_disabled_by_hw(), but they are not well defined and are tied to >> THP support. >> >> This series addresses both issues by introducing a new well defined API >> to query PMD-sized page support: pgtable_has_pmd_leaves(). Using this >> new helper, we ensure that mTHP remains enabled even when the >> architecture or CPU doesn't support PMD-sized pages. >> >> Thanks to David Hildenbrand for suggesting this improvement and for >> providing guidance (all bugs and misconceptions are mine). >> >> This applies to Linus tree 08d0d3466664 ("Merge tag 'net-7.1-rc2' >> of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net") >> >> NOTE: I used Claude Code Opus 4.6 to *review* the series before >> posting. It did find one issue where a pgtable_has_pmd_leaves() >> check was missing when assining huge_shmem_orders_inherit in >> shmem_init(). >> >> v4 >> -- >> - Use static key for pgtable_has_pmd_leaves() API (Lance) >> - Moved shmem pgtable_has_pmd_leaves() check to >> shmem_allowable_huge_orders() (Baolin) >> - Default pgtable_has_pmd_leaves() implementation to >> IS_ENABLED(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE) (Zi) >> - Dropped patch “mm: thp: x86: cleanup PSE feature bit usage” (Dave) >> >> v3 >> -- >> - Rebased on top of latest Linus tree >> - Removed i915 patch as driver dropped has_transparent_hugepage() usage >> - Moved init_arch_has_pmd_leaves() call in start_kernel() to avoid conflict >> with early_param handlers clearing CPU feature flags >> - Fixed build error with CONFIG_MMU=n (kernel test robot) >> - Fixed huge_anon_orders_inherit default setting when !pgtable_pmd_leaves() (Baolin) >> - Small commit changelog improvements >> >> v2 >> -- >> - Added support for always enabling mTHPs for shmem (Baolin) >> - Improved commits changelog & added reviewed-by >> >> v1 >> -- >> - Call init_arch_has_pmd_leaves() from start_kernel() >> - Keep pgtable_has_pmd_leaves() calls tied to CONFIG_TRANSPARENT_HUGEPAGE (David) >> - Clear PUD_ORDER when clearing PMD_ORDER (David) >> - Small changelog improvements (David) >> - Rebased on top of latest mm-new >> >> Luiz Capitulino (9): >> docs: tmpfs: remove implementation detail reference >> mm: introduce pgtable_has_pmd_leaves() >> drivers: dax: use pgtable_has_pmd_leaves() >> drivers: nvdimm: use pgtable_has_pmd_leaves() >> mm: debug_vm_pgtable: use pgtable_has_pmd_leaves() >> mm: shmem: drop has_transparent_hugepage() usage >> treewide: introduce arch_has_pmd_leaves() >> mm: replace thp_disabled_by_hw() with pgtable_has_pmd_leaves() >> mm: thp: always enable mTHP support >> >> Documentation/filesystems/tmpfs.rst | 5 ++-- >> arch/mips/include/asm/pgtable.h | 4 +-- >> arch/mips/mm/tlb-r4k.c | 4 +-- >> arch/powerpc/include/asm/book3s/64/hash-4k.h | 2 +- >> arch/powerpc/include/asm/book3s/64/hash-64k.h | 2 +- >> arch/powerpc/include/asm/book3s/64/pgtable.h | 10 ++++---- >> arch/powerpc/include/asm/book3s/64/radix.h | 2 +- >> arch/powerpc/mm/book3s64/hash_pgtable.c | 4 +-- >> arch/s390/include/asm/pgtable.h | 4 +-- >> arch/x86/include/asm/pgtable.h | 4 +-- >> drivers/dax/dax-private.h | 2 +- >> drivers/nvdimm/pfn_devs.c | 6 +++-- >> include/linux/huge_mm.h | 7 ------ >> include/linux/pgtable.h | 19 ++++++++++++-- >> init/main.c | 1 + >> mm/debug_vm_pgtable.c | 20 +++++++-------- >> mm/huge_memory.c | 25 +++++++++++++------ >> mm/memory.c | 11 +++++++- >> mm/shmem.c | 21 +++++++++------- >> 19 files changed, 93 insertions(+), 60 deletions(-) >> >> -- >> 2.53.0 >> >