From nobody Thu Apr 9 10:43:51 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 801BD38F94A for ; Wed, 8 Apr 2026 20:23:35 +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=1775679816; cv=none; b=TcjHJRnJMmL0KsvZ7C1xKfd8tVMYUuVl7Q8KEASqYGBleC8YQ9KICg2y6ZHeTm/uIkTjE/VuspPoQTbGVpMWOl2940aDsDPlof+BXEv7G+Lh3wBJCHZiFR3YJ9Ivzyq0jnc4h+PbIYebYdkL51JPEGTpcRfhhxE/77hnyl9vsZY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775679816; c=relaxed/simple; bh=iArTyi2V/4c9LLoSsOUqpFzZcNSNLXWOzYr1MEiSCFk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RkY9U1sTQ9EmOJoOfBmk7+uK+RC4FN2uBxIiqDmbkfkGdJ+Qx6IzNg6/z1b7T2NxVYTC/sdckHMIj2mpoR8IxfY11WJRy68PiOBQObT0yCtc2ll2IjBKs9EcjqceNN1I0kWz8/sZT4XR3d+2MQFLuL0rXD5IBeILPjiJi/WzL2g= 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=ZQuFmBoU; 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="ZQuFmBoU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1775679814; 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=+7hGKGZGeLjF560FpYHuHn8OsBr5eDLDlL3Qi8Vk24g=; b=ZQuFmBoUGHw8TJTY78oF+bZh6TCO9PQeO3j9R8uh6tAhfYLz2UpxKkHLbW9cfYGDo/TXK+ Zq8hfJiS3lNeZAi5zFvnUb5vzLG1Ai0sRpyHdVjKoEPsLvDgltCafEB2QAFDX2MCKJXUY1 AEBTyQth1JDzLQ28SuW72R4+mBuRONI= Received: from mx-prod-mc-03.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-570-2BpvvUxYPdC4kJPgcnusLw-1; Wed, 08 Apr 2026 16:23:30 -0400 X-MC-Unique: 2BpvvUxYPdC4kJPgcnusLw-1 X-Mimecast-MFC-AGG-ID: 2BpvvUxYPdC4kJPgcnusLw_1775679808 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-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9CAA51955F16; Wed, 8 Apr 2026 20:23:28 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.88.140]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 4FFE2180075B; Wed, 8 Apr 2026 20:23:27 +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 v3 09/10] mm: thp: always enable mTHP support Date: Wed, 8 Apr 2026 16:23:04 -0400 Message-ID: <6dea717fe8c86003e7da33c9a7623b834649d5ee.1775679721.git.luizcap@redhat.com> 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" If PMD-sized pages are not supported on an architecture (ie. the arch implements arch_has_pmd_leaves() and it returns false) then the current code disables all THP, including mTHP. This commit fixes this by allowing mTHP to be always enabled for all archs. When PMD-sized pages are not supported, its sysfs entry won't be created and their mapping will be disallowed at page-fault time. Similarly, this commit implements the following changes for shmem: - In shmem_allowable_huge_orders(): drop the pgtable_has_pmd_leaves() check so that mTHP sizes are considered - In shmem_alloc_and_add_folio(): don't consider PMD and PUD orders when PMD-sized pages are not supported by the CPU Signed-off-by: Luiz Capitulino --- mm/huge_memory.c | 13 ++++++++----- mm/shmem.c | 4 +++- 2 files changed, 11 insertions(+), 6 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 86e489c0a150..6de3d8ebc35c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -118,6 +118,9 @@ unsigned long __thp_vma_allowable_orders(struct vm_area= _struct *vma, else supported_orders =3D THP_ORDERS_ALL_FILE_DEFAULT; =20 + if (!pgtable_has_pmd_leaves()) + supported_orders &=3D ~(BIT(PMD_ORDER) | BIT(PUD_ORDER)); + orders &=3D supported_orders; if (!orders) return 0; @@ -125,7 +128,7 @@ unsigned long __thp_vma_allowable_orders(struct vm_area= _struct *vma, if (!vma->vm_mm) /* vdso */ return 0; =20 - if (!pgtable_has_pmd_leaves() || vma_thp_disabled(vma, vm_flags, forced_c= ollapse)) + if (vma_thp_disabled(vma, vm_flags, forced_collapse)) return 0; =20 /* khugepaged doesn't collapse DAX vma, but page fault is fine. */ @@ -787,7 +790,7 @@ static int __init hugepage_init_sysfs(struct kobject **= hugepage_kobj) * disable all other sizes. powerpc's PMD_ORDER isn't a compile-time * constant so we have to do this here. */ - if (!anon_orders_configured) + if (!anon_orders_configured && pgtable_has_pmd_leaves()) huge_anon_orders_inherit =3D BIT(PMD_ORDER); =20 *hugepage_kobj =3D kobject_create_and_add("transparent_hugepage", mm_kobj= ); @@ -809,6 +812,9 @@ static int __init hugepage_init_sysfs(struct kobject **= hugepage_kobj) } =20 orders =3D THP_ORDERS_ALL_ANON | THP_ORDERS_ALL_FILE_DEFAULT; + if (!pgtable_has_pmd_leaves()) + orders &=3D ~(BIT(PMD_ORDER) | BIT(PUD_ORDER)); + order =3D highest_order(orders); while (orders) { thpsize =3D thpsize_create(order, *hugepage_kobj); @@ -908,9 +914,6 @@ static int __init hugepage_init(void) int err; struct kobject *hugepage_kobj; =20 - if (!pgtable_has_pmd_leaves()) - return -EINVAL; - /* * hugepages can't be allocated by the buddy allocator */ diff --git a/mm/shmem.c b/mm/shmem.c index 613393eae5a9..b49a30475cb0 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1839,7 +1839,7 @@ unsigned long shmem_allowable_huge_orders(struct inod= e *inode, vm_flags_t vm_flags =3D vma ? vma->vm_flags : 0; unsigned int global_orders; =20 - if (!pgtable_has_pmd_leaves() || (vma && vma_thp_disabled(vma, vm_flags, = shmem_huge_force))) + if (vma && vma_thp_disabled(vma, vm_flags, shmem_huge_force)) return 0; =20 global_orders =3D shmem_huge_global_enabled(inode, index, write_end, @@ -1947,6 +1947,8 @@ static struct folio *shmem_alloc_and_add_folio(struct= vm_fault *vmf, =20 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) orders =3D 0; + else if (!pgtable_has_pmd_leaves()) + orders &=3D ~(BIT(PMD_ORDER) | BIT(PUD_ORDER)); =20 if (orders > 0) { suitable_orders =3D shmem_suitable_orders(inode, vmf, --=20 2.53.0