From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 38234525A89 for ; Fri, 18 Sep 2026 20:23:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789762997; cv=none; b=hNLrKwhpeN7HrmQf3CKlz+pbR9jglzntPZW0d81JnzhUkGDchfdfQjabl8goAfmwSjQNPYeQXq4BAhAOmTHCZIjCQ9lvr2J8AKbh7L58OU0MFMfCQ7Ciqv63m4fO49BKPRpmFwbGAEuD3OZHTxugFuQ+kdmVkGaWP3yPnmxxY+o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789762997; c=relaxed/simple; bh=mts4fRVKUarRTv/D/cqu2O4V5O+wURxs/swnsjdvbMg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TrGm9tChUsFEIvGRUSW9sYtSrWAdUN9lIOtxskzQd7BoZ2fTr4oP6Md3RLRxO0AoBoaJueAmLmc2A8X4PFCTo0jHvWu5uqmokqO5Ia09hI4kZ9bYZNG/voJ/7yfyM38Rro8JxM3WqYhEV1pQRt9wQ8ukNu3bjYezqKjAsXmnXOw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KRO8mE4Q; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KRO8mE4Q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9135F1F000FF; Fri, 18 Sep 2026 20:23:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789762996; bh=jMNQNlEwmiuLJhmuM/5YUT/yMbKaucQuszeHmhLwONQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=KRO8mE4QI67Tt6rV1s06qXUHa62HU5/c3vJdk5Kvt4K3j0K5o2TVsxOrGu2Yxmaqo 5SShVgxZl+gxU5lWsrFbEoQXw5DEKoQPvT1fgfTvNC8LnIlEm7Kq766oJFDPBoJTe6 3WKxEYUmchY6Yh9SQ9LP8FDiicFYMo1BTf2qKzvJIzXEj61VtOjSgHEm7pm3vcy2rH /T52FJcA77bfDgOtl7fJL+kwn1MUi6qmYOp/enaPBcsamt307qP0I9F+Op+o+Tyh+X nOBD/gsStGGdqZEztyNYLHllBv51Ww8MFz8lHTosZQW1S1UIXX9heNvUTNPSNoueVW nB+hzx5ZKV/+Q== Message-ID: Date: Fri, 18 Sep 2026 22:23:06 +0200 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 v8 00/14] mm: thp: always enable mTHP support To: Luiz Capitulino , Usama Arif , linux-kernel@vger.kernel.org, linux-mm@kvack.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, 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, dev.jain@arm.com References: <970c8f34-3cf4-4c6c-931c-b132e3bc6838@redhat.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/18/26 16:01, Luiz Capitulino wrote: > > > On 9/18/26 6:37 AM, Usama Arif wrote: >> >> >> On 18/09/2026 02:45, Luiz Capitulino wrote: >>> Introduction >>> ============ >>> >>> 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. >> >> >> Hi Luiz, >> >> Sorry for asking this so late in the series, but which CPUs lack support for >> PMD sized pages? >> >> Is this series mainly for PowerPC? > > No :) > > The architectures that have conditional PMD page support (ie. discovered > at run-time via has_transparent_hugepage()) are x86, s390, powerpc and > mips. > > For x86 for example, even on 64-bit there are cases where the PSE bit > may not be present (eg. some errata and by hypervisor CPUID masking). > > That being said, the main goal of the series is that > has_transparent_hugepage() is overloaded: it has different semantics on > those architectures and is used to gate all THP support (which is not > the right thing to do for mTHP). Yes, and I hope that we can then follow-up with similar PUD support cleanup to rework some of that CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD magic. -- Cheers, David