Re: [PATCH v3 06/12] mm: track active portions of a section at boot

From: Andrew Morton
Date: Thu Jan 19 2017 - 19:14:33 EST


On Thu, 19 Jan 2017 14:07:13 -0800 Dan Williams <dan.j.williams@xxxxxxxxx> wrote:

> Prepare for hot{plug,remove} of sub-ranges of a section by tracking a
> section active bitmask, each bit representing 2MB (SECTION_SIZE (128M) /
> map_active bitmask length (64)).
>
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -1083,6 +1083,8 @@ struct mem_section_usage {
> unsigned long pageblock_flags[0];
> };
>
> +void section_active_init(unsigned long pfn, unsigned long nr_pages);
> +
> struct page;
> struct page_ext;
> struct mem_section {
> @@ -1224,6 +1226,7 @@ void sparse_init(void);
> #else
> #define sparse_init() do {} while (0)
> #define sparse_index_init(_sec, _nid) do {} while (0)
> +#define section_active_init(_pfn, _nr_pages) do {} while (0)

Using a #define for this is crappy. A static inline does typechecking
and can suppress unused-var warnings in callers.

> #endif /* CONFIG_SPARSEMEM */
>
> /*
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 68ccf5bcdbb2..9a3ab6c245a8 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6352,10 +6352,12 @@ void __init free_area_init_nodes(unsigned long *max_zone_pfn)
>
> /* Print out the early node map */
> pr_info("Early memory node ranges\n");
> - for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid)
> + for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
> pr_info(" node %3d: [mem %#018Lx-%#018Lx]\n", nid,
> (u64)start_pfn << PAGE_SHIFT,
> ((u64)end_pfn << PAGE_SHIFT) - 1);
> + section_active_init(start_pfn, end_pfn - start_pfn);

section_active_init() can be __init, methinks. We don't want to carry
the extra .text after boot.

--- a/include/linux/mmzone.h~mm-track-active-portions-of-a-section-at-boot-fix
+++ a/include/linux/mmzone.h
@@ -1083,7 +1083,7 @@ struct mem_section_usage {
unsigned long pageblock_flags[0];
};

-void section_active_init(unsigned long pfn, unsigned long nr_pages);
+void __init section_active_init(unsigned long pfn, unsigned long nr_pages);

struct page;
struct page_ext;
@@ -1226,6 +1226,10 @@ void sparse_init(void);
#else
#define sparse_init() do {} while (0)
#define sparse_index_init(_sec, _nid) do {} while (0)
+static inline void section_active_init(unsigned long pfn,
+ unsigned long nr_pages)
+{
+}
#define section_active_init(_pfn, _nr_pages) do {} while (0)
#endif /* CONFIG_SPARSEMEM */

--- a/mm/sparse.c~mm-track-active-portions-of-a-section-at-boot-fix
+++ a/mm/sparse.c
@@ -168,13 +168,13 @@ void __meminit mminit_validate_memmodel_
}
}

-static int section_active_index(phys_addr_t phys)
+static int __init section_active_index(phys_addr_t phys)
{
return (phys & ~(PA_SECTION_MASK)) / SECTION_ACTIVE_SIZE;
}

-static unsigned long section_active_mask(unsigned long pfn,
- unsigned long nr_pages)
+static unsigned long __init section_active_mask(unsigned long pfn,
+ unsigned long nr_pages)
{
int idx_start, idx_size;
phys_addr_t start, size;
@@ -195,7 +195,7 @@ static unsigned long section_active_mask
return ((1UL << idx_size) - 1) << idx_start;
}

-void section_active_init(unsigned long pfn, unsigned long nr_pages)
+void __init section_active_init(unsigned long pfn, unsigned long nr_pages)
{
int end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
int i, start_sec = pfn_to_section_nr(pfn);
_