Re: [PATCH v2] memblock: move reserve_bootmem_range() to memblock.c and make it static

[Lorenzo Stoakes (Oracle)]

On Mon, Mar 23, 2026 at 09:20:42AM +0200, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@xxxxxxxxxx>
>
> reserve_bootmem_region() is only called from
> memmap_init_reserved_pages() and it was in mm/mm_init.c because of its
> dependecies on static init_deferred_page().
>
> Since init_deferred_page() is not static anymore, move
> reserve_bootmem_region(), rename it to memmap_init_reserved_range() and
> make it static.
>
> Update the comment describing it to better reflect what the function
> does and drop bogus comment about reserved pages in free_bootmem_page().
>
> Update memblock test stubs to reflect the core changes.
>
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>

LGTM and passed local tests so:

Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@xxxxxxxxxx>

> ---
>  include/linux/bootmem_info.h      |  4 ----
>  include/linux/mm.h                |  3 ---
>  mm/memblock.c                     | 31 ++++++++++++++++++++++++++++---
>  mm/mm_init.c                      | 25 -------------------------
>  tools/include/linux/mm.h          |  2 --
>  tools/testing/memblock/internal.h |  9 +++++++++
>  tools/testing/memblock/mmzone.c   |  4 ----
>  7 files changed, 37 insertions(+), 41 deletions(-)
>
> diff --git a/include/linux/bootmem_info.h b/include/linux/bootmem_info.h
> index 4c506e76a808..492ceeb1cdf8 100644
> --- a/include/linux/bootmem_info.h
> +++ b/include/linux/bootmem_info.h
> @@ -44,10 +44,6 @@ static inline void free_bootmem_page(struct page *page)
>  {
>  	enum bootmem_type type = bootmem_type(page);
>
> -	/*
> -	 * The reserve_bootmem_region sets the reserved flag on bootmem
> -	 * pages.
> -	 */
>  	VM_BUG_ON_PAGE(page_ref_count(page) != 2, page);
>
>  	if (type == SECTION_INFO || type == MIX_SECTION_INFO)
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index abb4963c1f06..764d10fdfb5d 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3686,9 +3686,6 @@ extern unsigned long free_reserved_area(void *start, void *end,
>
>  extern void adjust_managed_page_count(struct page *page, long count);
>
> -extern void reserve_bootmem_region(phys_addr_t start,
> -				   phys_addr_t end, int nid);
> -
>  /* Free the reserved page into the buddy system, so it gets managed. */
>  void free_reserved_page(struct page *page);
>
> diff --git a/mm/memblock.c b/mm/memblock.c
> index b3ddfdec7a80..d504205cdbf5 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -973,7 +973,7 @@ __init void memmap_init_kho_scratch_pages(void)
>  	/*
>  	 * Initialize struct pages for free scratch memory.
>  	 * The struct pages for reserved scratch memory will be set up in
> -	 * reserve_bootmem_region()
> +	 * memmap_init_reserved_pages()
>  	 */
>  	__for_each_mem_range(i, &memblock.memory, NULL, NUMA_NO_NODE,
>  			     MEMBLOCK_KHO_SCRATCH, &start, &end, &nid) {
> @@ -2240,6 +2240,31 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
>  	return end_pfn - start_pfn;
>  }
>
> +/*
> + * Initialised pages do not have PageReserved set. This function is called
> + * for each reserved range and marks the pages PageReserved.
> + * When deferred initialization of struct pages is enabled it also ensures
> + * that struct pages are properly initialised.
> + */
> +static void __init memmap_init_reserved_range(phys_addr_t start,
> +					      phys_addr_t end, int nid)
> +{
> +	unsigned long pfn;
> +
> +	for_each_valid_pfn(pfn, PFN_DOWN(start), PFN_UP(end)) {
> +		struct page *page = pfn_to_page(pfn);
> +
> +		init_deferred_page(pfn, nid);
> +
> +		/*
> +		 * no need for atomic set_bit because the struct
> +		 * page is not visible yet so nobody should
> +		 * access it yet.
> +		 */
> +		__SetPageReserved(page);
> +	}
> +}
> +
>  static void __init memmap_init_reserved_pages(void)
>  {
>  	struct memblock_region *region;
> @@ -2259,7 +2284,7 @@ static void __init memmap_init_reserved_pages(void)
>  		end = start + region->size;
>
>  		if (memblock_is_nomap(region))
> -			reserve_bootmem_region(start, end, nid);
> +			memmap_init_reserved_range(start, end, nid);
>
>  		memblock_set_node(start, region->size, &memblock.reserved, nid);
>  	}
> @@ -2284,7 +2309,7 @@ static void __init memmap_init_reserved_pages(void)
>  			if (!numa_valid_node(nid))
>  				nid = early_pfn_to_nid(PFN_DOWN(start));
>
> -			reserve_bootmem_region(start, end, nid);
> +			memmap_init_reserved_range(start, end, nid);
>  		}
>  	}
>  }
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index df34797691bd..ea8d3de43470 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -772,31 +772,6 @@ void __meminit init_deferred_page(unsigned long pfn, int nid)
>  	__init_deferred_page(pfn, nid);
>  }
>
> -/*
> - * Initialised pages do not have PageReserved set. This function is
> - * called for each range allocated by the bootmem allocator and
> - * marks the pages PageReserved. The remaining valid pages are later
> - * sent to the buddy page allocator.
> - */
> -void __meminit reserve_bootmem_region(phys_addr_t start,
> -				      phys_addr_t end, int nid)
> -{
> -	unsigned long pfn;
> -
> -	for_each_valid_pfn(pfn, PFN_DOWN(start), PFN_UP(end)) {
> -		struct page *page = pfn_to_page(pfn);
> -
> -		__init_deferred_page(pfn, nid);
> -
> -		/*
> -		 * no need for atomic set_bit because the struct
> -		 * page is not visible yet so nobody should
> -		 * access it yet.
> -		 */
> -		__SetPageReserved(page);
> -	}
> -}
> -
>  /* If zone is ZONE_MOVABLE but memory is mirrored, it is an overlapped init */
>  static bool __meminit
>  overlap_memmap_init(unsigned long zone, unsigned long *pfn)
> diff --git a/tools/include/linux/mm.h b/tools/include/linux/mm.h
> index 028f3faf46e7..74cbd51dbea2 100644
> --- a/tools/include/linux/mm.h
> +++ b/tools/include/linux/mm.h
> @@ -32,8 +32,6 @@ static inline phys_addr_t virt_to_phys(volatile void *address)
>  	return (phys_addr_t)address;
>  }
>
> -void reserve_bootmem_region(phys_addr_t start, phys_addr_t end, int nid);
> -
>  static inline void totalram_pages_inc(void)
>  {
>  }
> diff --git a/tools/testing/memblock/internal.h b/tools/testing/memblock/internal.h
> index 009b97bbdd22..eb02d5771f4c 100644
> --- a/tools/testing/memblock/internal.h
> +++ b/tools/testing/memblock/internal.h
> @@ -29,4 +29,13 @@ static inline unsigned long free_reserved_area(void *start, void *end,
>  	return 0;
>  }
>
> +#define for_each_valid_pfn(pfn, start_pfn, end_pfn)                     \
> +       for ((pfn) = (start_pfn); (pfn) < (end_pfn); (pfn)++)
> +
> +static inline void init_deferred_page(unsigned long pfn, int nid)
> +{
> +}
> +
> +#define __SetPageReserved(p)	((void)(p))
> +
>  #endif
> diff --git a/tools/testing/memblock/mmzone.c b/tools/testing/memblock/mmzone.c
> index d3d58851864e..e719450f81cb 100644
> --- a/tools/testing/memblock/mmzone.c
> +++ b/tools/testing/memblock/mmzone.c
> @@ -11,10 +11,6 @@ struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
>  	return NULL;
>  }
>
> -void reserve_bootmem_region(phys_addr_t start, phys_addr_t end, int nid)
> -{
> -}
> -
>  void atomic_long_set(atomic_long_t *v, long i)
>  {
>  }
> --
> 2.53.0
>

FYI I saw the below when running make in tools/testing/memblock, doesn't look
related to this change but maybe something to address?


cc -I. -I../../include -Wall -O2 -fsanitize=address -fsanitize=undefined -D CONFIG_PHYS_ADDR_T_64BIT   -c -o memblock.o memblock.c
memblock.c: In function ‘memblock_add_range.isra’:
memblock.c:710:17: warning: ‘end_rgn’ may be used uninitialized [-Wmaybe-uninitialized]
  710 |                 memblock_merge_regions(type, start_rgn, end_rgn);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
memblock.c:616:42: note: ‘end_rgn’ was declared here
  616 |         int idx, nr_new, start_rgn = -1, end_rgn;
      |                                          ^~~~~~~