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Date: Sun, 12 Jul 2026 00:12:30 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Muchun Song <songmuchun@bytedance.com>
Cc: David Hildenbrand <david@kernel.org>, Shuah Khan <shuah@kernel.org>,
 Lorenzo Stoakes <ljs@kernel.org>, "Liam R . Howlett" <liam@infradead.org>,
 Vlastimil Babka <vbabka@kernel.org>, Mike Rapoport <rppt@kernel.org>, Suren
 Baghdasaryan <surenb@google.com>, Michal Hocko <mhocko@suse.com>,
 linux-mm@kvack.org, linux-kernel@vger.kernel.org,
 linux-kselftest@vger.kernel.org, muchun.song@linux.dev
Subject: Re: [PATCH] selftests/mm: remove obsolete hugetlb vmemmap test
Message-Id: <20260712001230.5c3491ee33460c98bef8c22a@linux-foundation.org>
In-Reply-To: <20260710092427.3459121-1-songmuchun@bytedance.com>
References: <20260710092427.3459121-1-songmuchun@bytedance.com>
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On Fri, 10 Jul 2026 17:24:27 +0800 Muchun Song <songmuchun@bytedance.com> wrote:

> The hugetlb vmemmap selftest was added to check the old HVO
> layout where tail vmemmap pages reused the head page.  That
> assumption no longer matches the current HVO mapping layout.
> 
> HVO now keeps a private backing page for the head vmemmap page
> and remaps redundant tail vmemmap pages to a shared read-only
> backing page.  The old page flag check is therefore testing an
> obsolete implementation detail rather than the current ABI or
> behavior.
> 
> Remove the stale test and its build, run, and ignore entries.
> 
> ...
>
> --- a/tools/testing/selftests/mm/.gitignore
> +++ b/tools/testing/selftests/mm/.gitignore
> @@ -3,11 +3,9 @@ cow
>  hugepage-mmap
>  hugepage-mremap
>  hugepage-shm
> -hugepage-vmemmap
>  hugetlb-mmap
>  hugetlb-mremap
>  hugetlb-shm
> -hugetlb-vmemmap
>  hugetlb-madvise
>  hugetlb-read-hwpoison
>  hugetlb-soft-offline

We should leave these .gitignore entries in place.  Please see
https://lore.kernel.org/CAHk-=wiHK5_oBUdUiNAaevmN9f-ORe+QBqbRefAZaw-RbgEn3w@mail.gmail.com

I'll queue a -fix for this.