Re: [PATCH V2 4/6] mm: rename the global section array to mem_sections

From: David Hildenbrand
Date: Tue Jun 01 2021 - 04:23:05 EST


On 31.05.21 11:19, Dong Aisheng wrote:
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@xxxxxxxxxxxxxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: kexec@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Dong Aisheng <aisheng.dong@xxxxxxx>
---
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.

--
Thanks,

David / dhildenb