From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 DB6123B95EC for ; Fri, 18 Sep 2026 01:47:11 +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=1789696056; cv=none; b=tT/jpQH9OlU23i2OylX+LDtK5XkDLJcqYqYwonOoUUL4JalbvgQIyJyqAgRbqsvnTJHk5js26ugTeD1dam2TRCpyBpAU/ssnnZegBubcc9bBdnPs048lkS83D90iTWDpzaHhBVY2Bl3zefj2MJiv3FWIa+X58Nd1TQe2lpdVSKo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789696056; c=relaxed/simple; bh=jH9ShoSZX0rAxFQGNEuxIH4YWfhH0wY9gnTRKR71iP8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=FWIFlUI5zvwXyDT9MfP8y/emj2ctnoNcO9jFiMM5xS9stoKzDNvZ3X+10l6V66+sOjzH6Dn/Mn4Oa/ULEE4qk4dQegC0pYF0V5EjnfqIe6JIdjC3Ve7vPpAjgR06mGWsd8aqY8aogQed7E8AQVGb+1cLet+oSXjKWdm3qAWGa4M= 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=OnhIaxhJ; 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="OnhIaxhJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1789696029; 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=9ovPTbvLEJJOqEFcDDpslczGlymPsHZBK7w/POdlYcQ=; b=OnhIaxhJ98ReFQnAdFW/xNkFIJ1j+IAzxGjORZ+48XZKITH7qZPcZbp7ydUcC+K9ImIePe 0YhUrZwwAi3yVrj0ovXyysFtRgX61BIEEUEwfbZNb9CBe/cwMPOL7pHKEixMulMklrU8Hk b6rgrprMt/5kWSY+XxYAxTvVznqoaik= 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-458-ngUFKrJONAmcmwzqvcMYeA-1; Thu, 17 Sep 2026 21:47:04 -0400 X-MC-Unique: ngUFKrJONAmcmwzqvcMYeA-1 X-Mimecast-MFC-AGG-ID: ngUFKrJONAmcmwzqvcMYeA_1789696021 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (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 8A7F61954229; Fri, 18 Sep 2026 01:47:01 +0000 (UTC) Received: from lcapitul-thinkpadt14gen3.rmtcaqc.csb (headnet05.pony-001.prod.iad2.dc.redhat.com [10.2.32.117]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id E4B9718002A6; Fri, 18 Sep 2026 01:46:57 +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, 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, usama.arif@linux.dev Subject: [PATCH v8 14/14] mm: thp: always enable mTHP support Date: Thu, 17 Sep 2026 21:45:35 -0400 Message-ID: <752f528f0fed5cdc9de12b54260b0495d4e5a6cb.1789695931.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 10.30.177.111 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 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 a06025b87e7c..a2d6de3ea988 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -189,6 +189,15 @@ 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; @@ -196,7 +205,7 @@ 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. */ @@ -979,7 +988,7 @@ 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); @@ -1001,6 +1010,15 @@ 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); @@ -1091,9 +1109,6 @@ 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 bc2de3a7c1ea..8c0f7e3efeeb 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2046,11 +2046,14 @@ 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); /* @@ -2058,7 +2061,7 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode, * sysfs configs. */ if (!vma || !vma_is_anon_shmem(vma) || shmem_huge_force) - return global_orders; + return global_orders & ~disabled_orders; /* * Following the 'deny' semantics of the top level, force the huge @@ -2072,7 +2075,7 @@ 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); @@ -2083,6 +2086,7 @@ 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; } @@ -5630,7 +5634,7 @@ 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