From nobody Wed Feb 11 05:14:41 2026 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 D9EAD311979 for ; Mon, 9 Feb 2026 22:14:53 +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=1770675295; cv=none; b=fcZkIgoVFQZpIz1C6eyD6D1aFctBvzdgWL8H9h5nvvELxHxzmrfocr43bS8oU07sT1884tjag3GaaSOyeA4NGfwvMnoQCCE4h3liTelAv3NbSL15wbgJ7CRQIdZUw9Y6Vdmwhclh5oWqMHHVsbRWBDn9o0UtmXZoMVC4suK1GaQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770675295; c=relaxed/simple; bh=Xim7z9ude0Zoty6IkIGXRqDnjc7Xbawb1ub+f64UUdk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ehflV7AAk6MOfyAsDDkrVIkz6zUbocxHEXJxlfhPJGoXkER8499YDt/Q7FvaKHjX1s0uT/H9d+D522fF5j8TumDTdgdLQC8ACncH0zs40xtm2DPLbHQycRoqBpNBLyaoFWOnQ7VZsU0zWTp7bHij9Q2C5qW+31+2eKCqjiGuvSI= 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=GoztIG9S; 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="GoztIG9S" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1770675292; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rGs9hCTZyZ7Pjx1oR/68kmPjlLwJFnt3KGvTvJCfD2s=; b=GoztIG9SpB8rWsVfhZzwp04Z/GV6lW6esLcsI7DJj/a4mbqq5ZZHdUZWpo/s6bzCTRm5SE 6umq0bZkFjMVocM9qa6ALHXUnYzwHXxd1yUXXEL+Q8H8G/0SVZfouppUfbBOJMal2vdzPq 4/Tv6MWlyCeRW8CUeXXX/+n6unE17TU= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-652-FgOUuNvCPre4UmMlbkiGkw-1; Mon, 09 Feb 2026 17:14:49 -0500 X-MC-Unique: FgOUuNvCPre4UmMlbkiGkw-1 X-Mimecast-MFC-AGG-ID: FgOUuNvCPre4UmMlbkiGkw_1770675288 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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5A5E11800464; Mon, 9 Feb 2026 22:14:48 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.65.66]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id C6ACA1800464; Mon, 9 Feb 2026 22:14:46 +0000 (UTC) From: Luiz Capitulino To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, david@kernel.org, baolin.wang@linux.alibaba.com Cc: ryan.roberts@arm.com, akpm@linux-foundation.org, lorenzo.stoakes@oracle.com Subject: [PATCH v2 02/11] mm: introduce pgtable_has_pmd_leaves() Date: Mon, 9 Feb 2026 17:14:24 -0500 Message-ID: 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-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Content-Type: text/plain; charset="utf-8" Currently, we have two helpers that check for PMD-sized pages but have different names and slightly different semantics: - has_transparent_hugepage(): the name suggests it checks if THP is enabled, but when CONFIG_TRANSPARENT_HUGEPAGE=3Dy and the architecture implements this helper, it actually checks if the CPU supports PMD-sized pages - thp_disabled_by_hw(): the name suggests it checks if THP is disabled by the hardware, but it just returns a cached value acquired with has_transparent_hugepage(). This helper is used in fast paths This commit introduces a new helper called pgtable_has_pmd_leaves() which is intended to replace both has_transparent_hugepage() and thp_disabled_by_hw(). pgtable_has_pmd_leaves() has very clear semantics: it returns true if the CPU supports PMD-sized pages and false otherwise. It always returns a cached value, so it can be used in fast paths. The new helper requires an initialization step which is performed by init_arch_has_pmd_leaves(). We call init_arch_has_pmd_leaves() very early during boot in start_kernel() so that users of the API can call it from __setup() handlers. The next commits will convert users of both has_transparent_hugepage() and thp_disabled_by_hw() to pgtable_has_pmd_leaves(). Signed-off-by: Luiz Capitulino --- include/linux/pgtable.h | 7 +++++++ init/main.c | 1 + mm/memory.c | 8 ++++++++ 3 files changed, 16 insertions(+) diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 652f287c1ef6..6733f90a1da4 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -2017,6 +2017,13 @@ static inline const char *pgtable_level_to_str(enum = pgtable_level level) } } =20 +extern bool __arch_has_pmd_leaves; +static inline bool pgtable_has_pmd_leaves(void) +{ + return __arch_has_pmd_leaves; +} +void __init init_arch_has_pmd_leaves(void); + #endif /* !__ASSEMBLY__ */ =20 #if !defined(MAX_POSSIBLE_PHYSMEM_BITS) && !defined(CONFIG_64BIT) diff --git a/init/main.c b/init/main.c index b84818ad9685..ad1209fffcde 100644 --- a/init/main.c +++ b/init/main.c @@ -1036,6 +1036,7 @@ void start_kernel(void) smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */ early_numa_node_init(); boot_cpu_hotplug_init(); + init_arch_has_pmd_leaves(); =20 print_kernel_cmdline(saved_command_line); /* parameters may set static keys */ diff --git a/mm/memory.c b/mm/memory.c index da360a6eb8a4..4c25a3c453c6 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -177,6 +177,14 @@ static int __init init_zero_pfn(void) } early_initcall(init_zero_pfn); =20 +bool __arch_has_pmd_leaves __read_mostly; +EXPORT_SYMBOL(__arch_has_pmd_leaves); + +void __init init_arch_has_pmd_leaves(void) +{ + __arch_has_pmd_leaves =3D has_transparent_hugepage(); +} + void mm_trace_rss_stat(struct mm_struct *mm, int member) { trace_rss_stat(mm, member); --=20 2.53.0