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 838DE2741B6 for ; Fri, 24 Jul 2026 01:35:44 +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=1784856946; cv=none; b=qbGKtuPkh+/Al5y01hzrO1214OrKkU9UNi/R7ebkMnm+mSI7RNxb/keVeIG5OpdO6aIfKdQx/iHr4xuDcw2eaGBX3n3SANxUZ0P3wohuxuZpPdNscqKR2sk9g650bkHhoN+ji7P3djpX36veQbMdZJo4/SUH+kfHLs6DgbdFzPY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784856946; c=relaxed/simple; bh=SzlEPn3zXXD/0uUd8oDs22F/ZYp8Zi34wwK0cbg9xpU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tmYP/sjjRMvqQ4idVl545hhCPz1dPpbv0Yp80Dd+9ybxs0RonV6bDqWQu6pF3ZBq3Bb+/8oFAeiYKOkcjihbnAxC930hjMJQL/nLAPl1QCRctIXAh5yMWns28S+ORpWjKAijGcAzvfa6F217hwUK3gw1mWdlYyYDQk82dYiOJ4c= 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=Omr7iMeu; 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="Omr7iMeu" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1784856943; 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=8NGeKqua+tRU3jPUjhDe7h+RXR8SmOKilK5RCupyqUY=; b=Omr7iMeuoHN80ivSgzuIY63MDLLlGDu1ljRvNxQBqF8SLflOtRoiXKS6NGzbda5jd73LgT 5anL/+JhoR6klPAoAMGJAkq3guNXkSsjQP8NKVryYZ/WGJK34GWtGdTbYuFiq5lcn+MCw0 3QHrybUhG4igtQmQzGR9WkteM8MivAc= 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-317-1-f-MQAMNVqJKz5xu6vCGw-1; Thu, 23 Jul 2026 21:35:37 -0400 X-MC-Unique: 1-f-MQAMNVqJKz5xu6vCGw-1 X-Mimecast-MFC-AGG-ID: 1-f-MQAMNVqJKz5xu6vCGw_1784856934 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 E1B051944EB2; Fri, 24 Jul 2026 01:35:33 +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 672B6180059A; Fri, 24 Jul 2026 01:35:30 +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 14/14] mm: thp: always enable mTHP support Date: Thu, 23 Jul 2026 21:34:18 -0400 Message-ID: <1a11c6075971d7321bb115ea16a2ec2e0cdfadc0.1784856856.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: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 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 - Filter out PMD and PUD orders from allowable orders when PMD-sized pages are not supported by the CPU Reviewed-by: Baolin Wang Signed-off-by: Luiz Capitulino --- mm/huge_memory.c | 25 ++++++++++++++++++++----- mm/shmem.c | 14 +++++++++----- 2 files changed, 29 insertions(+), 10 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 78dd16513a11..385a305e7af6 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -129,6 +129,15 @@ unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma, else supported_orders = THP_ORDERS_ALL_FILE_DEFAULT; + if (!pgtable_has_pmd_leaves()) { + /* + * If the CPU does not support PMD leaves, assume for + * now that it does not support PUD leaves and disable + * both folio orders. + */ + supported_orders &= ~(BIT(PMD_ORDER) | BIT(PUD_ORDER)); + } + orders &= supported_orders; if (!orders) return 0; @@ -136,7 +145,7 @@ unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma, if (!vma->vm_mm) /* vdso */ return 0; - if (!pgtable_has_pmd_leaves() || vma_thp_disabled(vma, vm_flags, forced_collapse)) + if (vma_thp_disabled(vma, vm_flags, forced_collapse)) return 0; /* khugepaged doesn't collapse DAX vma, but page fault is fine. */ @@ -874,7 +883,7 @@ 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 = BIT(PMD_ORDER); *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); @@ -896,6 +905,15 @@ static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj) } orders = THP_ORDERS_ALL_ANON | THP_ORDERS_ALL_FILE_DEFAULT; + if (!pgtable_has_pmd_leaves()) { + /* + * If the CPU does not support PMD leaves, assume for + * now that it does not support PUD leaves and disable + * both folio orders. + */ + orders &= ~(BIT(PMD_ORDER) | BIT(PUD_ORDER)); + } + order = highest_order(orders); while (orders) { thpsize = thpsize_create(order, *hugepage_kobj); @@ -1010,9 +1028,6 @@ static int __init hugepage_init(void) int err; struct kobject *hugepage_kobj; - 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 4d2e1b91ec26..008df558af23 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1830,16 +1830,19 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode, unsigned long mask = READ_ONCE(huge_shmem_orders_always); unsigned long within_size_orders = READ_ONCE(huge_shmem_orders_within_size); vm_flags_t vm_flags = vma ? vma->vm_flags : 0; - unsigned int global_orders; + unsigned int global_orders, disabled_orders = 0; - 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; + if (!pgtable_has_pmd_leaves()) + disabled_orders = BIT(PMD_ORDER); + global_orders = shmem_huge_global_enabled(inode, index, write_end, shmem_huge_force, vma, vm_flags); /* Tmpfs huge pages allocation */ if (!vma || !vma_is_anon_shmem(vma)) - return global_orders; + return global_orders & ~disabled_orders; /* * Following the 'deny' semantics of the top level, force the huge @@ -1853,7 +1856,7 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode, * means non-PMD sized THP can not override 'huge' mount option now. */ if (shmem_huge == SHMEM_HUGE_FORCE) - return READ_ONCE(huge_shmem_orders_inherit); + return READ_ONCE(huge_shmem_orders_inherit) & ~disabled_orders; /* Allow mTHP that will be fully within i_size. */ mask |= shmem_get_orders_within_size(inode, within_size_orders, index, 0); @@ -1864,6 +1867,7 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode, if (global_orders > 0) mask |= READ_ONCE(huge_shmem_orders_inherit); + mask &= ~disabled_orders; return THP_ORDERS_ALL_FILE_DEFAULT & mask; } @@ -5395,7 +5399,7 @@ void __init shmem_init(void) * Default to setting PMD-sized THP to inherit the global setting and * disable all other multi-size THPs. */ - if (!shmem_orders_configured) + if (!shmem_orders_configured && pgtable_has_pmd_leaves()) huge_shmem_orders_inherit = BIT(HPAGE_PMD_ORDER); #endif return; -- 2.55.0