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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: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 X-Mimecast-MFC-PROC-ID: TcHrH3n-8yIn02cy5vBXvBG4HTPNHnByEe7mVCKkvsY_1775679808 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-Rspamd-Queue-Id: 4109440002 X-Stat-Signature: o9p6c9ytzos3th7rm5abffp365apmnr7 X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1775679814-839758 X-HE-Meta: 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 oibxVliA J+JebdN98E+zVfhe+46T70zXEIOvByKhAWNLcoWEfuDeWhUyVk2XHKik3+tREn+Lcsbrqg81EPvC8KYnL3kgj4l1Elu0E2pWf5XdUTzWV9It0oaUQXC2lPjQXNO2+i6Q+4adwPRWYQKFcvD7P3yvjgSJxZtGbBcaa26fwe9sU/qEbIiAgDO17UmhmDUDIVvPJWL7CZshbpWEH7+EMBXLGCdZTIvrXKKEwmdecvIniKTqErUVe7aDVJMnQCpOK+rmh4oHnjR8GBqdY+nqdaAq83dNRuwr2HRNyo17a8XUeTYVqk7Taqxz195nAMbVlyLD1//Tv8wVYDDmY3Wc/RNCixgVxkw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 = THP_ORDERS_ALL_FILE_DEFAULT; + if (!pgtable_has_pmd_leaves()) + supported_orders &= ~(BIT(PMD_ORDER) | BIT(PUD_ORDER)); + orders &= 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; - 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. */ @@ -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 = BIT(PMD_ORDER); *hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj); @@ -809,6 +812,9 @@ 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()) + orders &= ~(BIT(PMD_ORDER) | BIT(PUD_ORDER)); + order = highest_order(orders); while (orders) { thpsize = thpsize_create(order, *hugepage_kobj); @@ -908,9 +914,6 @@ 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 613393eae5a9..b49a30475cb0 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1839,7 +1839,7 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode, vm_flags_t vm_flags = vma ? vma->vm_flags : 0; unsigned int global_orders; - 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; global_orders = shmem_huge_global_enabled(inode, index, write_end, @@ -1947,6 +1947,8 @@ static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf, if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) orders = 0; + else if (!pgtable_has_pmd_leaves()) + orders &= ~(BIT(PMD_ORDER) | BIT(PUD_ORDER)); if (orders > 0) { suitable_orders = shmem_suitable_orders(inode, vmf, -- 2.53.0