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From: David Hildenbrand <david@redhat.com>
To: Zi Yan <ziy@nvidia.com>,
	linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	"Matthew Wilcox (Oracle)" <willy@infradead.org>,
	Ryan Roberts <ryan.roberts@arm.com>,
	Hugh Dickins <hughd@google.com>,
	Yang Shi <yang@os.amperecomputing.com>,
	Miaohe Lin <linmiaohe@huawei.com>,
	Kefeng Wang <wangkefeng.wang@huawei.com>,
	Yu Zhao <yuzhao@google.com>, John Hubbard <jhubbard@nvidia.com>,
	linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] selftests/mm: make file-backed THP split work by setting force option
Date: Wed, 22 Jan 2025 16:27:35 +0100	[thread overview]
Message-ID: <d66cea11-9522-43f4-8590-2e11ed43a8e5@redhat.com> (raw)
In-Reply-To: <D78P942WWF1O.IKY64R8JAIJG@nvidia.com>

On 22.01.25 16:16, Zi Yan wrote:
> On Wed Jan 22, 2025 at 9:26 AM EST, David Hildenbrand wrote:
>> On 22.01.25 13:40, Zi Yan wrote:
>>> Commit acd7ccb284b8 ("mm: shmem: add large folio support for tmpfs")
>>> changes huge=always to allocate THP/mTHP based on write size and
>>> split_huge_page_test does not write PMD size data, so file-back THP is not
>>> created during the test.
>>
>> Just curious, why can't we write PMD size data instead, to avoid messing
>> with the "force" option?
> 
> It also works. I used "force", because I notice that it is intended for
> testing. Using it might be more future proof, in case huge=always changes
> its semantics again in the future.

I recall discussing with Hugh in an upstream call that "force" is a 
relict from older times, so naturally I would have just adjusted the 
test case to trigger the PMD scenario. No strong opinion, though, was 
just wondering.

-- 
Cheers,

David / dhildenb



  reply	other threads:[~2025-01-22 15:27 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-01-22 12:40 Zi Yan
2025-01-22 12:40 ` [PATCH 2/3] mm/huge_memory: allow split shmem large folio to any lower order Zi Yan
2025-01-22 14:27   ` David Hildenbrand
2025-01-22 12:40 ` [PATCH 3/3] selftests/mm: test splitting file-backed THP " Zi Yan
2025-01-22 14:26 ` [PATCH 1/3] selftests/mm: make file-backed THP split work by setting force option David Hildenbrand
2025-01-22 15:16   ` Zi Yan
2025-01-22 15:27     ` David Hildenbrand [this message]
2025-01-22 15:42       ` Zi Yan

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