From: Lance Yang <lance.yang@linux.dev>
To: luizcap@redhat.com
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
david@kernel.org, baolin.wang@linux.alibaba.com, ziy@nvidia.com,
lance.yang@linux.dev, 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: Re: [PATCH v8 14/14] mm: thp: always enable mTHP support
Date: Sat, 3 Oct 2026 11:13:01 +0800 [thread overview]
Message-ID: <20261003031301.48957-1-lance.yang@linux.dev> (raw)
In-Reply-To: <752f528f0fed5cdc9de12b54260b0495d4e5a6cb.1789695931.git.luizcap@redhat.com>
On Thu, Sep 17, 2026 at 09:45:35PM -0400, Luiz Capitulino wrote:
>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
Nit: "and PUD" can go.
David mentioned
"
There is no need to disable PUD-orders, as shmem does not support PUD-orders
(unlike DAX). So you can keep it simpler here.
"
in v4
https://lore.kernel.org/all/ff7bcd65-d444-4da1-890e-75504303ec3f@kernel.org/
Cheers, Lance
next prev parent reply other threads:[~2026-10-03 3:13 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-18 1:45 [PATCH v8 00/14] " Luiz Capitulino
2026-09-18 1:45 ` [PATCH v8 01/14] docs: tmpfs: remove implementation detail reference Luiz Capitulino
2026-09-18 1:45 ` [PATCH v8 02/14] mm: shmem: shmem_getattr(): set blksize to highest supported THP order Luiz Capitulino
2026-10-02 19:11 ` David Hildenbrand (Arm)
2026-09-18 1:45 ` [PATCH v8 03/14] mm: introduce pgtable_has_pmd_leaves() Luiz Capitulino
2026-09-22 2:07 ` Zi Yan
2026-10-02 19:13 ` David Hildenbrand (Arm)
2026-09-18 1:45 ` [PATCH v8 04/14] drivers: dax: use pgtable_has_pmd_leaves() Luiz Capitulino
2026-09-22 2:08 ` Zi Yan
2026-10-02 19:15 ` David Hildenbrand (Arm)
2026-09-18 1:45 ` [PATCH v8 05/14] drivers: nvdimm: " Luiz Capitulino
2026-10-02 19:18 ` David Hildenbrand (Arm)
2026-09-18 1:45 ` [PATCH v8 06/14] mm: debug_vm_pgtable: " Luiz Capitulino
2026-10-02 19:19 ` David Hildenbrand (Arm)
2026-09-18 1:45 ` [PATCH v8 07/14] mm: shmem: allow THP support determination at folio allocation time Luiz Capitulino
2026-09-22 2:20 ` Zi Yan
2026-09-23 1:37 ` Luiz Capitulino
2026-10-02 19:23 ` David Hildenbrand (Arm)
2026-09-18 1:45 ` [PATCH v8 08/14] s390: move has_transparent_hugepage() out of THP guard Luiz Capitulino
2026-09-22 2:21 ` Zi Yan
2026-10-02 19:24 ` David Hildenbrand (Arm)
2026-09-18 1:45 ` [PATCH v8 09/14] powerpc: " Luiz Capitulino
2026-10-02 19:28 ` David Hildenbrand (Arm)
2026-09-18 1:45 ` [PATCH v8 10/14] mips: " Luiz Capitulino
2026-10-02 19:29 ` David Hildenbrand (Arm)
2026-09-18 1:45 ` [PATCH v8 11/14] x86: " Luiz Capitulino
2026-09-18 1:45 ` [PATCH v8 12/14] treewide: introduce arch_has_pmd_leaves() Luiz Capitulino
2026-09-22 2:26 ` Zi Yan
2026-09-18 1:45 ` [PATCH v8 13/14] mm: replace thp_disabled_by_hw() with pgtable_has_pmd_leaves() Luiz Capitulino
2026-10-02 19:32 ` David Hildenbrand (Arm)
2026-09-18 1:45 ` [PATCH v8 14/14] mm: thp: always enable mTHP support Luiz Capitulino
2026-09-18 9:01 ` Baolin Wang
2026-09-21 10:29 ` Usama Arif
2026-09-22 2:06 ` Luiz Capitulino
2026-10-03 3:13 ` Lance Yang [this message]
2026-09-18 10:37 ` [PATCH v8 00/14] " Usama Arif
2026-09-18 14:01 ` Luiz Capitulino
2026-09-18 20:23 ` David Hildenbrand (Arm)
2026-09-21 10:36 ` Usama Arif
2026-09-22 2:11 ` Luiz Capitulino
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