In function sparse_add/remove_one_section(), pgdat_resize_lock is used
to protect initialization/release of one mem_section. This looks not
necessary for current implementation.
Following is the current call trace of sparse_add/remove_one_section()
mem_hotplug_begin()
arch_add_memory()
add_pages()
__add_pages()
__add_section()
sparse_add_one_section()
mem_hotplug_done()
mem_hotplug_begin()
arch_remove_memory()
__remove_pages()
__remove_section()
sparse_remove_one_section()
mem_hotplug_done()
which shows these functions is protected by the global mem_hotplug_lock.
It won't face contention when accessing the mem_section.
Since the information needed in sparse_add_one_section() is node id to
allocate proper memory. This patch also changes the prototype of
sparse_add_one_section() to pass node id directly. This is intended to
reduce misleading that sparse_add_one_section() would touch pgdat.
Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
---
v2:
* adjust changelog to show this procedure is serialized by global
mem_hotplug_lock
---
include/linux/memory_hotplug.h | 2 +-
mm/memory_hotplug.c | 2 +-
mm/sparse.c | 17 +++++------------
3 files changed, 7 insertions(+), 14 deletions(-)
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 45a5affcab8a..3787d4e913e6 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -333,7 +333,7 @@ extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
unsigned long nr_pages, struct vmem_altmap *altmap);
extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
extern bool is_memblock_offlined(struct memory_block *mem);
-extern int sparse_add_one_section(struct pglist_data *pgdat,
+extern int sparse_add_one_section(int nid,
unsigned long start_pfn, struct vmem_altmap *altmap);
extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
unsigned long map_offset, struct vmem_altmap *altmap);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index f626e7e5f57b..5b3a3d7b4466 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -253,7 +253,7 @@ static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
if (pfn_valid(phys_start_pfn))
return -EEXIST;
- ret = sparse_add_one_section(NODE_DATA(nid), phys_start_pfn, altmap);
+ ret = sparse_add_one_section(nid, phys_start_pfn, altmap);
if (ret < 0)
return ret;
diff --git a/mm/sparse.c b/mm/sparse.c
index 33307fc05c4d..a4fdbcb21514 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -662,25 +662,24 @@ static void free_map_bootmem(struct page *memmap)
* set. If this is <=0, then that means that the passed-in
* map was not consumed and must be freed.
*/
-int __meminit sparse_add_one_section(struct pglist_data *pgdat,
- unsigned long start_pfn, struct vmem_altmap *altmap)
+int __meminit sparse_add_one_section(int nid, unsigned long start_pfn,
+ struct vmem_altmap *altmap)
{
unsigned long section_nr = pfn_to_section_nr(start_pfn);
struct mem_section *ms;
struct page *memmap;
unsigned long *usemap;
- unsigned long flags;
int ret;
/*
* no locking for this, because it does its own
* plus, it does a kmalloc
*/
- ret = sparse_index_init(section_nr, pgdat->node_id);
+ ret = sparse_index_init(section_nr, nid);
if (ret < 0 && ret != -EEXIST)
return ret;
ret = 0;
- memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, altmap);
+ memmap = kmalloc_section_memmap(section_nr, nid, altmap);
if (!memmap)
return -ENOMEM;
usemap = __kmalloc_section_usemap();
@@ -689,8 +688,6 @@ int __meminit sparse_add_one_section(struct pglist_data *pgdat,
return -ENOMEM;
}
- pgdat_resize_lock(pgdat, &flags);
-
ms = __pfn_to_section(start_pfn);
if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
ret = -EEXIST;
@@ -707,7 +704,6 @@ int __meminit sparse_add_one_section(struct pglist_data *pgdat,
sparse_init_one_section(ms, section_nr, memmap, usemap);
out:
- pgdat_resize_unlock(pgdat, &flags);
if (ret < 0) {
kfree(usemap);
__kfree_section_memmap(memmap, altmap);
@@ -769,10 +765,8 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
unsigned long map_offset, struct vmem_altmap *altmap)
{
struct page *memmap = NULL;
- unsigned long *usemap = NULL, flags;
- struct pglist_data *pgdat = zone->zone_pgdat;
+ unsigned long *usemap = NULL;
- pgdat_resize_lock(pgdat, &flags);
if (ms->section_mem_map) {
usemap = ms->pageblock_flags;
memmap = sparse_decode_mem_map(ms->section_mem_map,
@@ -780,7 +774,6 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
ms->section_mem_map = 0;
ms->pageblock_flags = NULL;
}
- pgdat_resize_unlock(pgdat, &flags);
clear_hwpoisoned_pages(memmap + map_offset,
PAGES_PER_SECTION - map_offset);
--
2.15.1
