From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 44E9645039 for ; Fri, 24 Jul 2026 01:34:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784856888; cv=none; b=KDGt6NKsGE7art9DB9Owh6cEaSXyH5QYtnZr0YAjH9RJPkVj9CZFGGRXP7coT9KQhJiakYp4adYpl9zzIA9VngG5XEHZNtCI7kOvsQ1LtlYQCF6ueu04as4xGIpqfxtKdGJQIVwNBIAp5Rb8UfN+EUBwoGMVhCoBZe9tk+fqWzc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784856888; c=relaxed/simple; bh=gqA3dc0gPhEgdycRpPLnseBEbrmn+1/dAQSfRQ4+/Ts=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type; b=QVVafa7XEOvNFij32I/1/jW01kWPPxK73D2rbzbW6n67pnsiJAtKRd3okwmSHORFJyjVfUFJWyMmJDixJfM119RgEU09CoBqvaQj/b1yImn7Iip1RvgPnoJxBr0SwuZz54B3flir9wnNiwFP21RqiWesW/URRPbJ3v/+P2XIPgk= 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=KLnKEKi5; arc=none smtp.client-ip=170.10.129.124 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="KLnKEKi5" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1784856886; 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; bh=xI+LRT8kY6CDYQcWOQ3Jqu9CtuH4Lj/6FnUZ6ovGQIo=; b=KLnKEKi518Rmq5EFToDU1zShvbf1PfF4mFCXFKj0QT1+9NLBTktzQXmzxwVpu9H+EA6t6b 8rjh5WKB14tOsgknkKnfYTpyzkPF3Ux5eCrPObC388Nh3lv4UQl+2av0BY+Lo2rjvzNLNq 5qNnXFuXKOT2Udf4Hhmp7ESHU7fFUwE= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-619-7wbqbz5JP3aw4mhfj6tAXg-1; Thu, 23 Jul 2026 21:34:40 -0400 X-MC-Unique: 7wbqbz5JP3aw4mhfj6tAXg-1 X-Mimecast-MFC-AGG-ID: 7wbqbz5JP3aw4mhfj6tAXg_1784856877 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id BE5CF1944EAD; Fri, 24 Jul 2026 01:34:35 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.80.238]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 61088180059C; Fri, 24 Jul 2026 01:34:30 +0000 (UTC) From: Luiz Capitulino To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, david@kernel.org, baolin.wang@linux.alibaba.com, ziy@nvidia.com, lance.yang@linux.dev Cc: 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, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, ira.weiny@intel.com, hughd@google.com, dave.hansen@linux.intel.com, djbw@kernel.org, vishal.l.verma@intel.com, dave.jiang@intel.com, akpm@linux-foundation.org, yintirui@huawei.com, ljs@kernel.org, dev.jain@arm.com Subject: [PATCH v6 00/14] mm: thp: always enable mTHP support Date: Thu, 23 Jul 2026 21:34:04 -0400 Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 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 mm-unstable 71a7a58818a3 ("fs: stable_page_flags(): simplify KPF_IDLE handling"). v6 -- - Rebased on top of mm-unstable (required a minor conflict resolution) - Added more Reviewed-by and Acked-by tags v5 -- - Moved init_arch_has_pmd_leaves() to mm_core_init() (David) - Renamed init_arch_has_pmd_leaves() to pgtable_leaf_support_init() (Lance) - Added new patch changing shmem_getattr() to set blksize according to highest supported THP order (Baolin) - Added new patches to move has_transparent_hugepage() out of CONFIG_TRANSPARENT_HUGEPAGE guards (Sashiko) - shmem_allowable_huge_orders(): rename variable and only disable PMD_ORDER (David) - Added to include/linux/pgtable.h (Sashiko) - Added new tags and removed Reviewed-by from changed patches v4 -- - Used 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 (14): docs: tmpfs: remove implementation detail reference mm: shmem: shmem_getattr(): set blksize to highest supported THP order 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: allow THP support determination at folio allocation time s390: move has_transparent_hugepage() out of THP guard powerpc: move has_transparent_hugepage() out of THP guard mips: move has_transparent_hugepage() out of THP guard x86: move has_transparent_hugepage() out of THP guard 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 | 6 ++-- arch/mips/mm/tlb-r4k.c | 8 ++--- 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 | 18 ++++++------ arch/powerpc/include/asm/book3s/64/radix.h | 14 ++++----- arch/powerpc/mm/book3s64/hash_pgtable.c | 8 ++--- arch/s390/include/asm/pgtable.h | 6 ++-- arch/x86/include/asm/pgtable.h | 12 ++++---- drivers/dax/dax-private.h | 2 +- drivers/nvdimm/pfn_devs.c | 6 ++-- include/linux/huge_mm.h | 7 ----- include/linux/pgtable.h | 20 +++++++++++-- mm/debug_vm_pgtable.c | 20 ++++++------- mm/huge_memory.c | 27 ++++++++++++----- mm/memory.c | 11 ++++++- mm/mm_init.c | 1 + mm/shmem.c | 29 ++++++++++++------- 19 files changed, 120 insertions(+), 84 deletions(-) -- 2.55.0