Sub-section hotplug support reduces the unit of operation of hotplug
from section-sized-units (PAGES_PER_SECTION) to sub-section-sized units
(PAGES_PER_SUBSECTION). Teach shrink_{zone,pgdat}_span() to consider
PAGES_PER_SUBSECTION boundaries as the points where pfn_valid(), not
valid_section(), can toggle.
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
include/linux/mmzone.h | 2 ++
mm/memory_hotplug.c | 29 ++++++++---------------------
2 files changed, 10 insertions(+), 21 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index cffde898e345..b13f0cddf75e 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1164,6 +1164,8 @@ static inline unsigned long section_nr_to_pfn(unsigned long sec)
#define SECTION_ACTIVE_SIZE ((1UL << SECTION_SIZE_BITS) / BITS_PER_LONG)
#define SECTION_ACTIVE_MASK (~(SECTION_ACTIVE_SIZE - 1))
+#define PAGES_PER_SUB_SECTION (SECTION_ACTIVE_SIZE / PAGE_SIZE)
+#define PAGE_SUB_SECTION_MASK (~(PAGES_PER_SUB_SECTION-1))
struct mem_section_usage {
/*
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index a76fc6a6e9fe..0d379da0f1a8 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -325,12 +325,8 @@ static unsigned long find_smallest_section_pfn(int nid, struct zone *zone,
unsigned long start_pfn,
unsigned long end_pfn)
{
- struct mem_section *ms;
-
- for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SECTION) {
- ms = __pfn_to_section(start_pfn);
-
- if (unlikely(!valid_section(ms)))
+ for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SUB_SECTION) {
+ if (unlikely(!pfn_valid(start_pfn)))
continue;
if (unlikely(pfn_to_nid(start_pfn) != nid))
@@ -350,15 +346,12 @@ static unsigned long find_biggest_section_pfn(int nid, struct zone *zone,
unsigned long start_pfn,
unsigned long end_pfn)
{
- struct mem_section *ms;
unsigned long pfn;
/* pfn is the end pfn of a memory section. */
pfn = end_pfn - 1;
- for (; pfn >= start_pfn; pfn -= PAGES_PER_SECTION) {
- ms = __pfn_to_section(pfn);
-
- if (unlikely(!valid_section(ms)))
+ for (; pfn >= start_pfn; pfn -= PAGES_PER_SUB_SECTION) {
+ if (unlikely(!pfn_valid(pfn)))
continue;
if (unlikely(pfn_to_nid(pfn) != nid))
@@ -380,7 +373,6 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
unsigned long z = zone_end_pfn(zone); /* zone_end_pfn namespace clash */
unsigned long zone_end_pfn = z;
unsigned long pfn;
- struct mem_section *ms;
int nid = zone_to_nid(zone);
zone_span_writelock(zone);
@@ -417,10 +409,8 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
* it check the zone has only hole or not.
*/
pfn = zone_start_pfn;
- for (; pfn < zone_end_pfn; pfn += PAGES_PER_SECTION) {
- ms = __pfn_to_section(pfn);
-
- if (unlikely(!valid_section(ms)))
+ for (; pfn < zone_end_pfn; pfn += PAGES_PER_SUB_SECTION) {
+ if (unlikely(!pfn_valid(pfn)))
continue;
if (page_zone(pfn_to_page(pfn)) != zone)
@@ -448,7 +438,6 @@ static void shrink_pgdat_span(struct pglist_data *pgdat,
unsigned long p = pgdat_end_pfn(pgdat); /* pgdat_end_pfn namespace clash */
unsigned long pgdat_end_pfn = p;
unsigned long pfn;
- struct mem_section *ms;
int nid = pgdat->node_id;
if (pgdat_start_pfn == start_pfn) {
@@ -485,10 +474,8 @@ static void shrink_pgdat_span(struct pglist_data *pgdat,
* has only hole or not.
*/
pfn = pgdat_start_pfn;
- for (; pfn < pgdat_end_pfn; pfn += PAGES_PER_SECTION) {
- ms = __pfn_to_section(pfn);
-
- if (unlikely(!valid_section(ms)))
+ for (; pfn < pgdat_end_pfn; pfn += PAGES_PER_SUB_SECTION) {
+ if (unlikely(!pfn_valid(pfn)))
continue;
if (pfn_to_nid(pfn) != nid)
