From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [95.215.58.181]) (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 2C500387367 for ; Thu, 9 Apr 2026 08:30:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.181 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775723407; cv=none; b=R/Lvhh2N97/7pLZqnICBZqOiJB3jPDC1SzUgsu2G+nkDKo7frm3hLknN26OqQYmlf+FgAEZhtVriXH88kL66j6Zp7vUkNLnT7lcbQlNRe+HMRv99PPsmUcjxBQMJmPeKPO1vuQGzg5JnLwBUxzMSWimNQIgoBtDQ5dgJPYb4rKs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775723407; c=relaxed/simple; bh=zrfxJnAwIlkAUWMcq1K5zrvPSu/aXvn05kqjO+FRNi4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=f08nOXGX8A9Al8QZpOghnPao9HSpuMmnr09hdjMWRv1C8TRoTAlWTPcXElfMGMOL0z7FlL8ngqtFRGDE7YrPJY/ZibhS346HpKKvL8cuyjunrmzmsxZ7PnaTY35FpCymed51T3+MOgxpZbnPvXT11RwYyn7C32ZnYQ/vax82QJw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=gKn52ztF; arc=none smtp.client-ip=95.215.58.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="gKn52ztF" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1775723402; 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=TG3Qdmc3lNsKjHzcIFMYLHvMSiJZlrsl5sNm+q7Fpf4=; b=gKn52ztF2FP3C+TwXjdoMyA1rNNVY9jZ4UKAWphquuDJP/cRFaH4VO9IRBArnsN7TDAdtr Y1/36Y8WzjmU9eE4JBYNIOyEepZ+djE9yYdlZP3LRIejQXBAOh3YIjVdcDEyLokHaXJB2+ svMCUveneaKphq4wfX2ie8yFWmQJSnI= From: Lance Yang To: luizcap@redhat.com 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, ziy@nvidia.com, ljs@kernel.org, Liam.Howlett@oracle.com, npache@redhat.com, dev.jain@arm.com, Lance Yang Subject: Re: [PATCH v3 00/10] mm: thp: always enable mTHP support Date: Thu, 9 Apr 2026 16:29:36 +0800 Message-Id: <20260409082936.50302-1-lance.yang@linux.dev> In-Reply-To: References: 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-Migadu-Flow: FLOW_OUT +Cc THP Some folks seem to be missing from CC for this series. Please run scripts/get_maintainer.pl; it's your friend :) Thanks, Lance On Wed, Apr 08, 2026 at 04:22:55PM -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 bfe62a454542 ("Merge tag 'soc-fixes-7.0-2' >of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc"). > >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 (10): > 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: rename has_transparent_hugepage() to arch_has_pmd_leaves() > mm: replace thp_disabled_by_hw() with pgtable_has_pmd_leaves() > mm: thp: always enable mTHP support > mm: thp: x86: cleanup PSE feature bit usage > > 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 | 6 ------ > arch/x86/include/asm/pgtable_32.h | 6 ++++++ > 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 | 15 +++++++------- > mm/memory.c | 10 +++++++++- > mm/shmem.c | 11 +++++----- > 20 files changed, 80 insertions(+), 60 deletions(-) > >-- >2.53.0 > >