On 01.06.21 10:37, Dong Aisheng wrote:

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

quoted

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.

Just because it's in Andrews tree doesn't mean it will end up upstream. ;)

Anyhow, no really strong opinion, it's simply unnecessary code churn 
that makes bisecting harder without real value IMHO.

-- 
Thanks,

David / dhildenb