mm/hotplug: prepare shrink_{zone, pgdat}_span for sub-section removal

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.

[osalvador@suse.de: fix shrink_{zone,node}_span]
  Link: http://lkml.kernel.org/r/20190717090725.23618-3-osalvador@suse.de
Link: http://lkml.kernel.org/r/156092351496.979959.12703722803097017492.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>	[ppc64]
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Wei Yang <richardw.yang@linux.intel.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 25 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index cf9d979a6498..85467914ad23 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -318,12 +318,8 @@ 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_SUBSECTION) {
+                if (unlikely(!pfn_valid(start_pfn)))
                         continue;
 
                 if (unlikely(pfn_to_nid(start_pfn) != nid))
@@ -343,15 +339,12 @@ 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_SUBSECTION) {
+                if (unlikely(!pfn_valid(pfn)))
                         continue;
 
                 if (unlikely(pfn_to_nid(pfn) != nid))
@@ -373,7 +366,6 @@ 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);
@@ -410,17 +402,15 @@ 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_SUBSECTION) {
+                if (unlikely(!pfn_valid(pfn)))
                         continue;
 
                 if (page_zone(pfn_to_page(pfn)) != zone)
                         continue;
 
-                 /* If the section is current section, it continues the loop */
-                if (start_pfn == pfn)
+                /* Skip range to be removed */
+                if (pfn >= start_pfn && pfn < end_pfn)
                         continue;
 
                 /* If we find valid section, we have nothing to do */
@@ -441,7 +431,6 @@ 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) {
@@ -478,17 +467,15 @@ 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_SUBSECTION) {
+                if (unlikely(!pfn_valid(pfn)))
                         continue;
 
                 if (pfn_to_nid(pfn) != nid)
                         continue;
 
-                 /* If the section is current section, it continues the loop */
-                if (start_pfn == pfn)
+                /* Skip range to be removed */
+                if (pfn >= start_pfn && pfn < end_pfn)
                         continue;
 
                 /* If we find valid section, we have nothing to do */