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[PATCH 10/14] mm: prepare to move subsection_map_init() to mm/sparse-vmemmap.c

David Hildenbrand (Arm) posted 14 patches 2 weeks, 6 days ago
There is a newer version of this series
[PATCH 10/14] mm: prepare to move subsection_map_init() to mm/sparse-vmemmap.c
Posted by David Hildenbrand (Arm) 2 weeks, 6 days ago 
We want to move subsection_map_init() to mm/sparse-vmemmap.c.

To prepare for getting rid of subsection_map_init() in mm/sparse.c
completely, use a static inline function for !CONFIG_SPARSEMEM_VMEMMAP.

While at it, move the declaration to internal.h and rename it to
"sparse_init_subsection_map()".

Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
---
 include/linux/mmzone.h |  3 ---
 mm/internal.h          | 12 ++++++++++++
 mm/mm_init.c           |  2 +-
 mm/sparse.c            |  6 +-----
 4 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 7bd0134c241c..b694c69dee04 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -2002,8 +2002,6 @@ struct mem_section_usage {
 	unsigned long pageblock_flags[0];
 };
 
-void subsection_map_init(unsigned long pfn, unsigned long nr_pages);
-
 struct page;
 struct page_ext;
 struct mem_section {
@@ -2396,7 +2394,6 @@ static inline unsigned long next_present_section_nr(unsigned long section_nr)
 #define sparse_vmemmap_init_nid_early(_nid) do {} while (0)
 #define sparse_vmemmap_init_nid_late(_nid) do {} while (0)
 #define pfn_in_present_section pfn_valid
-#define subsection_map_init(_pfn, _nr_pages) do {} while (0)
 #endif /* CONFIG_SPARSEMEM */
 
 /*
diff --git a/mm/internal.h b/mm/internal.h
index f98f4746ac41..5f5c45d80aca 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -960,12 +960,24 @@ void memmap_init_range(unsigned long, int, unsigned long, unsigned long,
 		unsigned long, enum meminit_context, struct vmem_altmap *, int,
 		bool);
 
+/*
+ * mm/sparse.c
+ */
 #ifdef CONFIG_SPARSEMEM
 void sparse_init(void);
 #else
 static inline void sparse_init(void) {}
 #endif /* CONFIG_SPARSEMEM */
 
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+void sparse_init_subsection_map(unsigned long pfn, unsigned long nr_pages);
+#else
+static inline void sparse_init_subsection_map(unsigned long pfn,
+		unsigned long nr_pages)
+{
+}
+#endif /* CONFIG_SPARSEMEM_VMEMMAP */
+
 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
 
 /*
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 969048f9b320..3c5f18537cd1 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1898,7 +1898,7 @@ static void __init free_area_init(void)
 		pr_info("  node %3d: [mem %#018Lx-%#018Lx]\n", nid,
 			(u64)start_pfn << PAGE_SHIFT,
 			((u64)end_pfn << PAGE_SHIFT) - 1);
-		subsection_map_init(start_pfn, end_pfn - start_pfn);
+		sparse_init_subsection_map(start_pfn, end_pfn - start_pfn);
 	}
 
 	/* Initialise every node */
diff --git a/mm/sparse.c b/mm/sparse.c
index b57c81e99340..7b0bfea73a9b 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -185,7 +185,7 @@ static void subsection_mask_set(unsigned long *map, unsigned long pfn,
 	bitmap_set(map, idx, end - idx + 1);
 }
 
-void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
+void __init sparse_init_subsection_map(unsigned long pfn, unsigned long nr_pages)
 {
 	int end_sec_nr = pfn_to_section_nr(pfn + nr_pages - 1);
 	unsigned long nr, start_sec_nr = pfn_to_section_nr(pfn);
@@ -207,10 +207,6 @@ void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
 		nr_pages -= pfns;
 	}
 }
-#else
-void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
-{
-}
 #endif
 
 /* Record a memory area against a node. */
-- 
2.43.0
Re: [PATCH 10/14] mm: prepare to move subsection_map_init() to mm/sparse-vmemmap.c
Posted by Mike Rapoport 2 weeks, 5 days ago 
On Tue, Mar 17, 2026 at 05:56:48PM +0100, David Hildenbrand (Arm) wrote:
> We want to move subsection_map_init() to mm/sparse-vmemmap.c.
> 
> To prepare for getting rid of subsection_map_init() in mm/sparse.c
> completely, use a static inline function for !CONFIG_SPARSEMEM_VMEMMAP.
> 
> While at it, move the declaration to internal.h and rename it to
> "sparse_init_subsection_map()".

Do we really need to rename it?

Maybe add a "global renaming patch on top, like

s/clear_subsection_map/subsection_map_clear/
s/fill_subsection_map/subsection_map_fill/

etc
 
> Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>

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

> ---
>  include/linux/mmzone.h |  3 ---
>  mm/internal.h          | 12 ++++++++++++
>  mm/mm_init.c           |  2 +-
>  mm/sparse.c            |  6 +-----
>  4 files changed, 14 insertions(+), 9 deletions(-)

-- 
Sincerely yours,
Mike.
Re: [PATCH 10/14] mm: prepare to move subsection_map_init() to mm/sparse-vmemmap.c
Posted by David Hildenbrand (Arm) 2 weeks, 3 days ago 
On 3/18/26 09:46, Mike Rapoport wrote:
> On Tue, Mar 17, 2026 at 05:56:48PM +0100, David Hildenbrand (Arm) wrote:
>> We want to move subsection_map_init() to mm/sparse-vmemmap.c.
>>
>> To prepare for getting rid of subsection_map_init() in mm/sparse.c
>> completely, use a static inline function for !CONFIG_SPARSEMEM_VMEMMAP.
>>
>> While at it, move the declaration to internal.h and rename it to
>> "sparse_init_subsection_map()".
> 
> Do we really need to rename it?

Given that I am placing it next to sparse_init(), yes I want to rename it.

> 
> Maybe add a "global renaming patch on top, like
> 
> s/clear_subsection_map/subsection_map_clear/
> s/fill_subsection_map/subsection_map_fill/

Well, these are all internal helpers in mm/sparse.c, not exposed to
other MM bits. :)

> 
> etc
>  
>> Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
> 
> Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

Thanks!

-- 
Cheers,

David
Re: [PATCH 10/14] mm: prepare to move subsection_map_init() to mm/sparse-vmemmap.c
Posted by Lorenzo Stoakes (Oracle) 2 weeks, 6 days ago 
On Tue, Mar 17, 2026 at 05:56:48PM +0100, David Hildenbrand (Arm) wrote:
> We want to move subsection_map_init() to mm/sparse-vmemmap.c.
>
> To prepare for getting rid of subsection_map_init() in mm/sparse.c
> completely, use a static inline function for !CONFIG_SPARSEMEM_VMEMMAP.
>
> While at it, move the declaration to internal.h and rename it to
> "sparse_init_subsection_map()".

Why not init_sparse_subsection_map()??
Or sparse_init_map_subsection()????
Or <all other permutations>

Joking that's fine ;)

>
> Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>

You've initialised the sparse subsection of my heart, so:

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

> ---
>  include/linux/mmzone.h |  3 ---
>  mm/internal.h          | 12 ++++++++++++
>  mm/mm_init.c           |  2 +-
>  mm/sparse.c            |  6 +-----
>  4 files changed, 14 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 7bd0134c241c..b694c69dee04 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -2002,8 +2002,6 @@ struct mem_section_usage {
>  	unsigned long pageblock_flags[0];
>  };
>
> -void subsection_map_init(unsigned long pfn, unsigned long nr_pages);
> -
>  struct page;
>  struct page_ext;
>  struct mem_section {
> @@ -2396,7 +2394,6 @@ static inline unsigned long next_present_section_nr(unsigned long section_nr)
>  #define sparse_vmemmap_init_nid_early(_nid) do {} while (0)
>  #define sparse_vmemmap_init_nid_late(_nid) do {} while (0)
>  #define pfn_in_present_section pfn_valid
> -#define subsection_map_init(_pfn, _nr_pages) do {} while (0)
>  #endif /* CONFIG_SPARSEMEM */
>
>  /*
> diff --git a/mm/internal.h b/mm/internal.h
> index f98f4746ac41..5f5c45d80aca 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -960,12 +960,24 @@ void memmap_init_range(unsigned long, int, unsigned long, unsigned long,
>  		unsigned long, enum meminit_context, struct vmem_altmap *, int,
>  		bool);
>
> +/*
> + * mm/sparse.c
> + */
>  #ifdef CONFIG_SPARSEMEM
>  void sparse_init(void);
>  #else
>  static inline void sparse_init(void) {}
>  #endif /* CONFIG_SPARSEMEM */
>
> +#ifdef CONFIG_SPARSEMEM_VMEMMAP
> +void sparse_init_subsection_map(unsigned long pfn, unsigned long nr_pages);
> +#else
> +static inline void sparse_init_subsection_map(unsigned long pfn,
> +		unsigned long nr_pages)
> +{
> +}
> +#endif /* CONFIG_SPARSEMEM_VMEMMAP */
> +
>  #if defined CONFIG_COMPACTION || defined CONFIG_CMA
>
>  /*
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index 969048f9b320..3c5f18537cd1 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -1898,7 +1898,7 @@ static void __init free_area_init(void)
>  		pr_info("  node %3d: [mem %#018Lx-%#018Lx]\n", nid,
>  			(u64)start_pfn << PAGE_SHIFT,
>  			((u64)end_pfn << PAGE_SHIFT) - 1);
> -		subsection_map_init(start_pfn, end_pfn - start_pfn);
> +		sparse_init_subsection_map(start_pfn, end_pfn - start_pfn);
>  	}
>
>  	/* Initialise every node */
> diff --git a/mm/sparse.c b/mm/sparse.c
> index b57c81e99340..7b0bfea73a9b 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -185,7 +185,7 @@ static void subsection_mask_set(unsigned long *map, unsigned long pfn,
>  	bitmap_set(map, idx, end - idx + 1);
>  }
>
> -void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
> +void __init sparse_init_subsection_map(unsigned long pfn, unsigned long nr_pages)
>  {
>  	int end_sec_nr = pfn_to_section_nr(pfn + nr_pages - 1);
>  	unsigned long nr, start_sec_nr = pfn_to_section_nr(pfn);
> @@ -207,10 +207,6 @@ void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
>  		nr_pages -= pfns;
>  	}
>  }
> -#else
> -void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
> -{
> -}
>  #endif
>
>  /* Record a memory area against a node. */
> --
> 2.43.0
>
Re: [PATCH 10/14] mm: prepare to move subsection_map_init() to mm/sparse-vmemmap.c
Posted by David Hildenbrand (Arm) 2 weeks, 3 days ago 
On 3/17/26 20:51, Lorenzo Stoakes (Oracle) wrote:
> On Tue, Mar 17, 2026 at 05:56:48PM +0100, David Hildenbrand (Arm) wrote:
>> We want to move subsection_map_init() to mm/sparse-vmemmap.c.
>>
>> To prepare for getting rid of subsection_map_init() in mm/sparse.c
>> completely, use a static inline function for !CONFIG_SPARSEMEM_VMEMMAP.
>>
>> While at it, move the declaration to internal.h and rename it to
>> "sparse_init_subsection_map()".
> 
> Why not init_sparse_subsection_map()??
> Or sparse_init_map_subsection()????
> Or <all other permutations>
> 
> Joking that's fine ;)

To match sparse_init() of course :)

-- 
Cheers,

David

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