The patch titled
Subject: mm, sparse: drop pgdat_resize_lock in sparse_add/remove_one_section()
has been added to the -mm tree. Its filename is
mm-sparse-drop-pgdat_resize_lock-in-sparse_add-remove_one_section.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-sparse-drop-pgdat_resize_lock-in-sparse_add-remove_one_section.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-sparse-drop-pgdat_resize_lock-in-sparse_add-remove_one_section.patch
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------------------------------------------------------
From: Wei Yang <richard.weiyang@xxxxxxxxx>
Subject: mm, sparse: drop pgdat_resize_lock in sparse_add/remove_one_section()
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.
Link: http://lkml.kernel.org/r/20181128091243.19249-1-richard.weiyang@xxxxxxxxx
Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/include/linux/memory_hotplug.h~mm-sparse-drop-pgdat_resize_lock-in-sparse_add-remove_one_section
+++ a/include/linux/memory_hotplug.h
@@ -335,7 +335,7 @@ extern void move_pfn_range_to_zone(struc
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(int nid, struct mem_section *ms,
unsigned long map_offset, struct vmem_altmap *altmap);
--- a/mm/memory_hotplug.c~mm-sparse-drop-pgdat_resize_lock-in-sparse_add-remove_one_section
+++ a/mm/memory_hotplug.c
@@ -253,7 +253,7 @@ static int __meminit __add_section(int n
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;
--- a/mm/sparse.c~mm-sparse-drop-pgdat_resize_lock-in-sparse_add-remove_one_section
+++ a/mm/sparse.c
@@ -662,25 +662,24 @@ static void free_map_bootmem(struct page
* 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(str
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(str
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);
@@ -778,10 +774,8 @@ void sparse_remove_one_section(int nid,
unsigned long map_offset, struct vmem_altmap *altmap)
{
struct page *memmap = NULL;
- unsigned long *usemap = NULL, flags;
- struct pglist_data *pgdat = NODE_DATA(nid);
+ 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,
@@ -789,7 +783,6 @@ void sparse_remove_one_section(int nid,
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);
_
Patches currently in -mm which might be from richard.weiyang@xxxxxxxxx are
mm-page_alloc-fix-calculation-of-pgdat-nr_zones.patch
mm-slub-remove-validation-on-cpu_slab-in-__flush_cpu_slab.patch
mm-slub-page-is-always-non-null-for-node_match.patch
mm-slub-record-final-state-of-slub-action-in-deactivate_slab.patch
mm-slub-improve-performance-by-skipping-checked-node-in-get_any_partial.patch
mm-remove-reset-of-pcp-counter-in-pageset_init.patch
vmscan-return-node_reclaim_noscan-in-node_reclaim-when-config_numa-is-n.patch
drivers-base-memoryc-remove-an-unnecessary-check-on-nr_mem_sections.patch
mm-check-nr_initialised-with-pages_per_section-directly-in-defer_init.patch
mm-sparse-drop-pgdat_resize_lock-in-sparse_add-remove_one_section.patch
