On Tue, Jun 1, 2021 at 4:22 PM David Hildenbrand [off-list ref] wrote:

On 31.05.21 11:19, Dong Aisheng wrote:

quoted

In order to distinguish the struct mem_section for a better code
readability and align with kernel doc [1] name below, change the
global mem section name to 'mem_sections' from 'mem_section'.

[1] Documentation/vm/memory-model.rst
"The `mem_section` objects are arranged in a two-dimensional array
called `mem_sections`."

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Young <redacted>
Cc: Baoquan He <redacted>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: kexec@lists.infradead.org
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
---
v1->v2:
  * no changes
---
  include/linux/mmzone.h | 10 +++++-----
  kernel/crash_core.c    |  4 ++--
  mm/sparse.c            | 16 ++++++++--------
  3 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index a6bfde85ddb0..0ed61f32d898 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h

@@ -1302,9 +1302,9 @@ struct mem_section {
  #define SECTION_ROOT_MASK   (SECTIONS_PER_ROOT - 1)

  #ifdef CONFIG_SPARSEMEM_EXTREME
-extern struct mem_section **mem_section;
+extern struct mem_section **mem_sections;
  #else
-extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
+extern struct mem_section mem_sections[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
  #endif

  static inline unsigned long *section_to_usemap(struct mem_section *ms)

@@ -1315,12 +1315,12 @@ static inline unsigned long *section_to_usemap(struct mem_section *ms)
  static inline struct mem_section *__nr_to_section(unsigned long nr)
  {
  #ifdef CONFIG_SPARSEMEM_EXTREME
-     if (!mem_section)
+     if (!mem_sections)
              return NULL;
  #endif
-     if (!mem_section[SECTION_NR_TO_ROOT(nr)])
+     if (!mem_sections[SECTION_NR_TO_ROOT(nr)])
              return NULL;
-     return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
+     return &mem_sections[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
  }
  extern unsigned long __section_nr(struct mem_section *ms);
  extern size_t mem_section_usage_size(void);

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 29cc15398ee4..fb1180d81b5a 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c

@@ -414,8 +414,8 @@ static int __init crash_save_vmcoreinfo_init(void)
      VMCOREINFO_SYMBOL(contig_page_data);
  #endif
  #ifdef CONFIG_SPARSEMEM
-     VMCOREINFO_SYMBOL_ARRAY(mem_section);
-     VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);
+     VMCOREINFO_SYMBOL_ARRAY(mem_sections);
+     VMCOREINFO_LENGTH(mem_sections, NR_SECTION_ROOTS);
      VMCOREINFO_STRUCT_SIZE(mem_section);
      VMCOREINFO_OFFSET(mem_section, section_mem_map);
      VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS);

diff --git a/mm/sparse.c b/mm/sparse.c
index d02ee6bb7cbc..6412010478f7 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c

@@ -24,12 +24,12 @@
   * 1) mem_section   - memory sections, mem_map's for valid memory
   */
  #ifdef CONFIG_SPARSEMEM_EXTREME
-struct mem_section **mem_section;
+struct mem_section **mem_sections;
  #else
-struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
+struct mem_section mem_sections[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
      ____cacheline_internodealigned_in_smp;
  #endif
-EXPORT_SYMBOL(mem_section);
+EXPORT_SYMBOL(mem_sections);

  #ifdef NODE_NOT_IN_PAGE_FLAGS
  /*

@@ -66,8 +66,8 @@ static void __init sparse_alloc_section_roots(void)

      size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
      align = 1 << (INTERNODE_CACHE_SHIFT);
-     mem_section = memblock_alloc(size, align);
-     if (!mem_section)
+     mem_sections = memblock_alloc(size, align);
+     if (!mem_sections)
              panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
                    __func__, size, align);
  }

@@ -103,14 +103,14 @@ static int __meminit sparse_index_init(unsigned long section_nr, int nid)
       *
       * The mem_hotplug_lock resolves the apparent race below.
       */
-     if (mem_section[root])
+     if (mem_sections[root])
              return 0;

      section = sparse_index_alloc(nid);
      if (!section)
              return -ENOMEM;

-     mem_section[root] = section;
+     mem_sections[root] = section;

      return 0;
  }

@@ -145,7 +145,7 @@ unsigned long __section_nr(struct mem_section *ms)
  #else
  unsigned long __section_nr(struct mem_section *ms)
  {
-     return (unsigned long)(ms - mem_section[0]);
+     return (unsigned long)(ms - mem_sections[0]);
  }
  #endif

I repeat: unnecessary code churn IMHO.

Hi David,

Thanks, i explained the reason during my last reply.
Andrew has already picked this patch to -mm tree.

Regards
Aisheng

--
Thanks,

David / dhildenb