From: "David Hildenbrand (arm)" <david@kernel.org>
To: Matthew Wilcox <willy@infradead.org>,
Usama Arif <usamaarif642@gmail.com>
Cc: ziy@nvidia.com, Andrew Morton <akpm@linux-foundation.org>,
lorenzo.stoakes@oracle.com, linux-mm@kvack.org,
hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev,
kas@kernel.org, baohua@kernel.org, dev.jain@arm.com,
baolin.wang@linux.alibaba.com, npache@redhat.com,
Liam.Howlett@oracle.com, ryan.roberts@arm.com, vbabka@suse.cz,
lance.yang@linux.dev, linux-kernel@vger.kernel.org,
kernel-team@meta.com
Subject: Re: [RFC 00/12] mm: PUD (1GB) THP implementation
Date: Mon, 2 Feb 2026 10:06:14 +0100 [thread overview]
Message-ID: <7d6f5fd3-9652-4e9d-89af-e81ce20df8ba@kernel.org> (raw)
In-Reply-To: <aYAhRjI2xNdtdvWY@casper.infradead.org>
On 2/2/26 05:00, Matthew Wilcox wrote:
> On Sun, Feb 01, 2026 at 04:50:17PM -0800, Usama Arif wrote:
>> This is an RFC series to implement 1GB PUD-level THPs, allowing
>> applications to benefit from reduced TLB pressure without requiring
>> hugetlbfs. The patches are based on top of
>> f9b74c13b773b7c7e4920d7bc214ea3d5f37b422 from mm-stable (6.19-rc6).
>
> I suggest this has not had enough testing. There are dozens of places
> in the MM which assume that if a folio is at leaast PMD size then it is
> exactly PMD size. Everywhere that calls folio_test_pmd_mappable() needs
> to be audited to make sure that it will work properly if the folio is
> larger than PMD size.
I think the hack (ehm trick) in this patch set is to do it just like dax
PUDs: only map through a PUD or through PTEs, not through PMDs.
That also avoids dealing with mapcounts until I sorted that out.
--
Cheers
David
next prev parent reply other threads:[~2026-02-02 9:06 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-02 0:50 Usama Arif
2026-02-02 0:50 ` [RFC 01/12] mm: add PUD THP ptdesc and rmap support Usama Arif
2026-02-02 10:44 ` Kiryl Shutsemau
2026-02-02 16:01 ` Zi Yan
2026-02-03 22:07 ` Usama Arif
2026-02-05 4:17 ` Matthew Wilcox
2026-02-05 4:21 ` Matthew Wilcox
2026-02-05 5:13 ` Usama Arif
2026-02-05 17:40 ` David Hildenbrand (Arm)
2026-02-05 18:05 ` Usama Arif
2026-02-05 18:11 ` Usama Arif
2026-02-02 12:15 ` Lorenzo Stoakes
2026-02-04 7:38 ` Usama Arif
2026-02-04 12:55 ` Lorenzo Stoakes
2026-02-05 6:40 ` Usama Arif
2026-02-02 0:50 ` [RFC 02/12] mm/thp: add mTHP stats infrastructure for PUD THP Usama Arif
2026-02-02 11:56 ` Lorenzo Stoakes
2026-02-05 5:53 ` Usama Arif
2026-02-02 0:50 ` [RFC 03/12] mm: thp: add PUD THP allocation and fault handling Usama Arif
2026-02-02 0:50 ` [RFC 04/12] mm: thp: implement PUD THP split to PTE level Usama Arif
2026-02-02 0:50 ` [RFC 05/12] mm: thp: add reclaim and migration support for PUD THP Usama Arif
2026-02-02 0:50 ` [RFC 06/12] selftests/mm: add PUD THP basic allocation test Usama Arif
2026-02-02 0:50 ` [RFC 07/12] selftests/mm: add PUD THP read/write access test Usama Arif
2026-02-02 0:50 ` [RFC 08/12] selftests/mm: add PUD THP fork COW test Usama Arif
2026-02-02 0:50 ` [RFC 09/12] selftests/mm: add PUD THP partial munmap test Usama Arif
2026-02-02 0:50 ` [RFC 10/12] selftests/mm: add PUD THP mprotect split test Usama Arif
2026-02-02 0:50 ` [RFC 11/12] selftests/mm: add PUD THP reclaim test Usama Arif
2026-02-02 0:50 ` [RFC 12/12] selftests/mm: add PUD THP migration test Usama Arif
2026-02-02 2:44 ` [RFC 00/12] mm: PUD (1GB) THP implementation Rik van Riel
2026-02-02 11:30 ` Lorenzo Stoakes
2026-02-02 15:50 ` Zi Yan
2026-02-04 10:56 ` Lorenzo Stoakes
2026-02-05 11:29 ` David Hildenbrand (arm)
2026-02-05 11:22 ` David Hildenbrand (arm)
2026-02-02 4:00 ` Matthew Wilcox
2026-02-02 9:06 ` David Hildenbrand (arm) [this message]
2026-02-03 21:11 ` Usama Arif
2026-02-02 11:20 ` Lorenzo Stoakes
2026-02-04 1:00 ` Usama Arif
2026-02-04 11:08 ` Lorenzo Stoakes
2026-02-04 11:50 ` Dev Jain
2026-02-04 12:01 ` Dev Jain
2026-02-05 6:08 ` Usama Arif
2026-02-02 16:24 ` Zi Yan
2026-02-03 23:29 ` Usama Arif
2026-02-04 0:08 ` Frank van der Linden
2026-02-05 5:46 ` Usama Arif
2026-02-05 18:07 ` Zi Yan
2026-02-07 23:22 ` Usama Arif
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