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Date: Wed, 11 Jun 2025 16:08:04 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
 nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, Alistair Popple
 <apopple@nvidia.com>, Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
 "Liam R. Howlett" <Liam.Howlett@oracle.com>, Vlastimil Babka
 <vbabka@suse.cz>, Mike Rapoport <rppt@kernel.org>, Suren Baghdasaryan
 <surenb@google.com>, Michal Hocko <mhocko@suse.com>, Zi Yan
 <ziy@nvidia.com>, Baolin Wang <baolin.wang@linux.alibaba.com>, Nico Pache
 <npache@redhat.com>, Ryan Roberts <ryan.roberts@arm.com>, Dev Jain
 <dev.jain@arm.com>, Dan Williams <dan.j.williams@intel.com>, Oscar Salvador
 <osalvador@suse.de>
Subject: Re: [PATCH v2 0/3] mm/huge_memory: vmf_insert_folio_*() and
 vmf_insert_pfn_pud() fixes
Message-Id: <20250611160804.89bc8b8cb570101e51b522e4@linux-foundation.org>
In-Reply-To: <20250611120654.545963-1-david@redhat.com>
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On Wed, 11 Jun 2025 14:06:51 +0200 David Hildenbrand <david@redhat.com> wrote:

> While working on improving vm_normal_page() and friends, I stumbled
> over this issues: refcounted "normal" pages must not be marked
> using pmd_special() / pud_special().

Why is this?

>
> ...
>
> I spent too much time trying to get the ndctl tests mentioned by Dan
> running (.config tweaks, memmap= setup, ... ), without getting them to
> pass even without these patches. Some SKIP, some FAIL, some sometimes
> suddenly SKIP on first invocation, ... instructions unclear or the tests
> are shaky. This is how far I got:

I won't include this in the [0/N] - it doesn't seem helpful for future
readers of the patchset.

I'll give the patchset a run in mm-new, but it feels like some more
baking is needed?

The [1/N] has cc:stable but there's nothing in there to explain this
decision.  How does the issues affect userspace?