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Subject: Re: [PATCH 5/6] userfaultfd: decouple fault reason from VMA flags
From: Muchun Song <muchun.song@linux.dev>
In-Reply-To: <20260823-uffd-vm-flags-v1-v1-5-3086981b33cf@kernel.org>
Date: Mon, 24 Aug 2026 16:12:41 +0800
Cc: Andrew Morton <akpm@linux-foundation.org>,
 David Hildenbrand <david@kernel.org>,
 Baolin Wang <baolin.wang@linux.alibaba.com>,
 Barry Song <baohua@kernel.org>,
 Dev Jain <dev.jain@arm.com>,
 Hugh Dickins <hughd@google.com>,
 Jann Horn <jannh@google.com>,
 Jason Gunthorpe <jgg@ziepe.ca>,
 John Hubbard <jhubbard@nvidia.com>,
 Jonathan Corbet <corbet@lwn.net>,
 Lance Yang <lance.yang@linux.dev>,
 "Liam R. Howlett" <liam@infradead.org>,
 Lorenzo Stoakes <ljs@kernel.org>,
 Masami Hiramatsu <mhiramat@kernel.org>,
 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
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 Nico Pache <nico.pache@linux.dev>,
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 Shakeel Butt <shakeel.butt@linux.dev>,
 Shuah Khan <skhan@linuxfoundation.org>,
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 Suren Baghdasaryan <surenb@google.com>,
 Usama Arif <usama.arif@linux.dev>,
 Vlastimil Babka <vbabka@kernel.org>,
 Zi Yan <ziy@nvidia.com>,
 linux-doc@vger.kernel.org,
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References: <20260823-uffd-vm-flags-v1-v1-0-3086981b33cf@kernel.org>
 <20260823-uffd-vm-flags-v1-v1-5-3086981b33cf@kernel.org>
To: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
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> On Aug 23, 2026, at 20:17, Mike Rapoport (Microsoft) <rppt@kernel.org> =
wrote:
>=20
> Introduce enum uffd_reason to define reasons for user faults rather =
than
> overload VM_UFFD_* VMA flags for that.
>=20
> Using a dedicated enum makes the code clearer and decoupling the fault
> reason from VMA flags clears the way for moving the uffd mode bits out
> of VMA namespace.
>=20
> No functional change.
>=20
> Assisted-by: copilot:claude-opus-4.6
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

Acked-by: Muchun Song <muchun.song@linux.dev> # for HugeTLB.

Thanks.