Re: [PATCH 1/2] mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE

From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Zi Yan <ziy@nvidia.com>
Cc: Gregory Price <gourry@gourry.net>,
	linux-kernel@vger.kernel.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Huacai Chen <chenhuacai@kernel.org>,
	WANG Xuerui <kernel@xen0n.name>,
	Madhavan Srinivasan <maddy@linux.ibm.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	"Christophe Leroy (CS GROUP)" <chleroy@kernel.org>,
	Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Lorenzo Stoakes <ljs@kernel.org>,
	"Liam R. Howlett" <Liam.Howlett@oracle.com>,
	Vlastimil Babka <vbabka@kernel.org>,
	Mike Rapoport <rppt@kernel.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Michal Hocko <mhocko@suse.com>,
	Matthew Brost <matthew.brost@intel.com>,
	Joshua Hahn <joshua.hahnjy@gmail.com>,
	Rakie Kim <rakie.kim@sk.com>, Byungchul Park <byungchul@sk.com>,
	Ying Huang <ying.huang@linux.alibaba.com>,
	Alistair Popple <apopple@nvidia.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Clark Williams <clrkwllms@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev,
	linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
	linux-s390@vger.kernel.org, linux-mm@kvack.org,
	linux-rt-devel@lists.linux.dev
Subject: Re: [PATCH 1/2] mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE
Date: Thu, 19 Mar 2026 19:15:10 +0100	[thread overview]
Message-ID: <feaf8a33-c716-418a-af32-aae4f1949a4b@kernel.org> (raw)
In-Reply-To: <1559C268-444B-4A64-A0B8-21B2FE49A5E2@nvidia.com>

On 3/19/26 19:12, Zi Yan wrote:
> On 19 Mar 2026, at 14:08, David Hildenbrand (Arm) wrote:
> 
>> On 3/19/26 16:24, Gregory Price wrote:
>>>
>>> HOTREMOVE has long been a thorn in my side, I appreciate you cleaning
>>> this up.
>>
>> On a long cardrive today I was wondering: do we still need a separate
>> MEMORY_HOTREMOVE
> 
> You mean merge HOTREMOVE into HOTPLUG?

Yes, only have a single config.

> I wondered the same. Is there
> a reason to only have HOTPLUG without HOTREMOVE?
In the past some architectures (e.g., s390x) did not support HOTREMOVE.
Then it made sense. I'm not sure if someone would want to build a kernel
with HOTPLUG but not have the bit of overhead for unplug+migration.

So I would guess nothing major speaks against it.

-- 
Cheers,

David