[v1] mm: memory hot(un)plug and SPARSEMEM cleanups

[PATCH 03/14] mm/Kconfig: make CONFIG_MEMORY_HOTPLUG depend on CONFIG_SPARSEMEM_VMEMMAP

Posted by David Hildenbrand (Arm) 2 weeks, 6 days ago

Ever since commit f8f03eb5f0f9 ("mm: stop making SPARSEMEM_VMEMMAP
user-selectable"), an architecture that supports CONFIG_SPARSEMEM_VMEMMAP
(by selecting SPARSEMEM_VMEMMAP_ENABLE) can no longer enable
CONFIG_SPARSEMEM without CONFIG_SPARSEMEM_VMEMMAP.

Right now, CONFIG_MEMORY_HOTPLUG is guarded by CONFIG_SPARSEMEM.

However, CONFIG_ARCH_ENABLE_MEMORY_HOTPLUG is only enabled by
* arm64: which selects SPARSEMEM_VMEMMAP_ENABLE
* loongarch: which selects SPARSEMEM_VMEMMAP_ENABLE
* powerpc (64bit): which selects SPARSEMEM_VMEMMAP_ENABLE
* riscv (64bit): which selects SPARSEMEM_VMEMMAP_ENABLE
* s390 with SPARSEMEM: which selects SPARSEMEM_VMEMMAP_ENABLE
* x86 (64bit): which selects SPARSEMEM_VMEMMAP_ENABLE

So, we can make CONFIG_MEMORY_HOTPLUG depend on CONFIG_SPARSEMEM_VMEMMAP
without affecting any setups.

Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
---
 mm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/Kconfig b/mm/Kconfig
index ebd8ea353687..c012944938a7 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -472,7 +472,7 @@ config ARCH_ENABLE_MEMORY_HOTREMOVE
 menuconfig MEMORY_HOTPLUG
 	bool "Memory hotplug"
 	select MEMORY_ISOLATION
-	depends on SPARSEMEM
+	depends on SPARSEMEM_VMEMMAP
 	depends on ARCH_ENABLE_MEMORY_HOTPLUG
 	depends on 64BIT
 	select NUMA_KEEP_MEMINFO if NUMA
-- 
2.43.0

Re: [PATCH 03/14] mm/Kconfig: make CONFIG_MEMORY_HOTPLUG depend on CONFIG_SPARSEMEM_VMEMMAP

Posted by Mike Rapoport 2 weeks, 5 days ago

On Tue, Mar 17, 2026 at 05:56:41PM +0100, David Hildenbrand (Arm) wrote:
> Ever since commit f8f03eb5f0f9 ("mm: stop making SPARSEMEM_VMEMMAP
> user-selectable"), an architecture that supports CONFIG_SPARSEMEM_VMEMMAP
> (by selecting SPARSEMEM_VMEMMAP_ENABLE) can no longer enable
> CONFIG_SPARSEMEM without CONFIG_SPARSEMEM_VMEMMAP.
> 
> Right now, CONFIG_MEMORY_HOTPLUG is guarded by CONFIG_SPARSEMEM.
> 
> However, CONFIG_ARCH_ENABLE_MEMORY_HOTPLUG is only enabled by
> * arm64: which selects SPARSEMEM_VMEMMAP_ENABLE
> * loongarch: which selects SPARSEMEM_VMEMMAP_ENABLE
> * powerpc (64bit): which selects SPARSEMEM_VMEMMAP_ENABLE
> * riscv (64bit): which selects SPARSEMEM_VMEMMAP_ENABLE
> * s390 with SPARSEMEM: which selects SPARSEMEM_VMEMMAP_ENABLE
> * x86 (64bit): which selects SPARSEMEM_VMEMMAP_ENABLE
> 
> So, we can make CONFIG_MEMORY_HOTPLUG depend on CONFIG_SPARSEMEM_VMEMMAP
> without affecting any setups.
> 
> Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>

Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

> ---
>  mm/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/Kconfig b/mm/Kconfig
> index ebd8ea353687..c012944938a7 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -472,7 +472,7 @@ config ARCH_ENABLE_MEMORY_HOTREMOVE
>  menuconfig MEMORY_HOTPLUG
>  	bool "Memory hotplug"
>  	select MEMORY_ISOLATION
> -	depends on SPARSEMEM
> +	depends on SPARSEMEM_VMEMMAP
>  	depends on ARCH_ENABLE_MEMORY_HOTPLUG
>  	depends on 64BIT
>  	select NUMA_KEEP_MEMINFO if NUMA
> -- 
> 2.43.0
> 

-- 
Sincerely yours,
Mike.

Re: [PATCH 03/14] mm/Kconfig: make CONFIG_MEMORY_HOTPLUG depend on CONFIG_SPARSEMEM_VMEMMAP

Posted by Lorenzo Stoakes (Oracle) 2 weeks, 6 days ago

On Tue, Mar 17, 2026 at 05:56:41PM +0100, David Hildenbrand (Arm) wrote:
> Ever since commit f8f03eb5f0f9 ("mm: stop making SPARSEMEM_VMEMMAP
> user-selectable"), an architecture that supports CONFIG_SPARSEMEM_VMEMMAP
> (by selecting SPARSEMEM_VMEMMAP_ENABLE) can no longer enable
> CONFIG_SPARSEMEM without CONFIG_SPARSEMEM_VMEMMAP.
>
> Right now, CONFIG_MEMORY_HOTPLUG is guarded by CONFIG_SPARSEMEM.
>
> However, CONFIG_ARCH_ENABLE_MEMORY_HOTPLUG is only enabled by
> * arm64: which selects SPARSEMEM_VMEMMAP_ENABLE
> * loongarch: which selects SPARSEMEM_VMEMMAP_ENABLE
> * powerpc (64bit): which selects SPARSEMEM_VMEMMAP_ENABLE
> * riscv (64bit): which selects SPARSEMEM_VMEMMAP_ENABLE
> * s390 with SPARSEMEM: which selects SPARSEMEM_VMEMMAP_ENABLE
> * x86 (64bit): which selects SPARSEMEM_VMEMMAP_ENABLE
>
> So, we can make CONFIG_MEMORY_HOTPLUG depend on CONFIG_SPARSEMEM_VMEMMAP
> without affecting any setups.
>
> Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>

Some risc-y business Dave but I believe in you! So:

Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>

> ---
>  mm/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/Kconfig b/mm/Kconfig
> index ebd8ea353687..c012944938a7 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -472,7 +472,7 @@ config ARCH_ENABLE_MEMORY_HOTREMOVE
>  menuconfig MEMORY_HOTPLUG
>  	bool "Memory hotplug"
>  	select MEMORY_ISOLATION
> -	depends on SPARSEMEM
> +	depends on SPARSEMEM_VMEMMAP
>  	depends on ARCH_ENABLE_MEMORY_HOTPLUG
>  	depends on 64BIT
>  	select NUMA_KEEP_MEMINFO if NUMA
> --
> 2.43.0
>