When a memory is added, we update zone's and pgdat's start_pfn and spanned_pages in the function __add_zone(). So we should revert them when the memory is removed. The patch adds a new function __remove_zone() to do this. CC: David Rientjes <rientjes@xxxxxxxxxx> CC: Jiang Liu <liuj97@xxxxxxxxx> CC: Len Brown <len.brown@xxxxxxxxx> CC: Christoph Lameter <cl@xxxxxxxxx> Cc: Minchan Kim <minchan.kim@xxxxxxxxx> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx> --- mm/memory_hotplug.c | 207 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 207 insertions(+) Index: linux-3.6/mm/memory_hotplug.c =================================================================== --- linux-3.6.orig/mm/memory_hotplug.c 2012-10-04 18:30:21.182698427 +0900 +++ linux-3.6/mm/memory_hotplug.c 2012-10-04 18:30:31.767709165 +0900 @@ -312,10 +312,213 @@ static int __meminit __add_section(int n return register_new_memory(nid, __pfn_to_section(phys_start_pfn)); } +/* find the smallest valid pfn in the range [start_pfn, end_pfn) */ +static int 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))) + continue; + + if (unlikely(pfn_to_nid(start_pfn)) != nid) + continue; + + if (zone && zone != page_zone(pfn_to_page(start_pfn))) + continue; + + return start_pfn; + } + + return 0; +} + +/* find the biggest valid pfn in the range [start_pfn, end_pfn). */ +static int 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))) + continue; + + if (unlikely(pfn_to_nid(pfn)) != nid) + continue; + + if (zone && zone != page_zone(pfn_to_page(pfn))) + continue; + + return pfn; + } + + return 0; +} + +static void shrink_zone_span(struct zone *zone, unsigned long start_pfn, + unsigned long end_pfn) +{ + unsigned long zone_start_pfn = zone->zone_start_pfn; + unsigned long zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages; + unsigned long pfn; + struct mem_section *ms; + int nid = zone_to_nid(zone); + + zone_span_writelock(zone); + if (zone_start_pfn == start_pfn) { + /* + * If the section is smallest section in the zone, it need + * shrink zone->zone_start_pfn and zone->zone_spanned_pages. + * In this case, we find second smallest valid mem_section + * for shrinking zone. + */ + pfn = find_smallest_section_pfn(nid, zone, end_pfn, + zone_end_pfn); + if (pfn) { + zone->zone_start_pfn = pfn; + zone->spanned_pages = zone_end_pfn - pfn; + } + } else if (zone_end_pfn == end_pfn) { + /* + * If the section is biggest section in the zone, it need + * shrink zone->spanned_pages. + * In this case, we find second biggest valid mem_section for + * shrinking zone. + */ + pfn = find_biggest_section_pfn(nid, zone, zone_start_pfn, + start_pfn); + if (pfn) + zone->spanned_pages = pfn - zone_start_pfn + 1; + } + + /* + * The section is not biggest or smallest mem_section in the zone, it + * only creates a hole in the zone. So in this case, we need not + * change the zone. But perhaps, the zone has only hole data. Thus + * 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))) + continue; + + if (page_zone(pfn_to_page(pfn)) != zone) + continue; + + /* If the section is current section, it continues the loop */ + if (start_pfn == pfn) + continue; + + /* If we find valid section, we have nothing to do */ + zone_span_writeunlock(zone); + return; + } + + /* The zone has no valid section */ + zone->zone_start_pfn = 0; + zone->spanned_pages = 0; + zone_span_writeunlock(zone); +} + +static void shrink_pgdat_span(struct pglist_data *pgdat, + unsigned long start_pfn, unsigned long end_pfn) +{ + unsigned long pgdat_start_pfn = pgdat->node_start_pfn; + unsigned long pgdat_end_pfn = + pgdat->node_start_pfn + pgdat->node_spanned_pages; + unsigned long pfn; + struct mem_section *ms; + int nid = pgdat->node_id; + + if (pgdat_start_pfn == start_pfn) { + /* + * If the section is smallest section in the pgdat, it need + * shrink pgdat->node_start_pfn and pgdat->node_spanned_pages. + * In this case, we find second smallest valid mem_section + * for shrinking zone. + */ + pfn = find_smallest_section_pfn(nid, NULL, end_pfn, + pgdat_end_pfn); + if (pfn) { + pgdat->node_start_pfn = pfn; + pgdat->node_spanned_pages = pgdat_end_pfn - pfn; + } + } else if (pgdat_end_pfn == end_pfn) { + /* + * If the section is biggest section in the pgdat, it need + * shrink pgdat->node_spanned_pages. + * In this case, we find second biggest valid mem_section for + * shrinking zone. + */ + pfn = find_biggest_section_pfn(nid, NULL, pgdat_start_pfn, + start_pfn); + if (pfn) + pgdat->node_spanned_pages = pfn - pgdat_start_pfn + 1; + } + + /* + * If the section is not biggest or smallest mem_section in the pgdat, + * it only creates a hole in the pgdat. So in this case, we need not + * change the pgdat. + * But perhaps, the pgdat has only hole data. Thus it check the 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))) + continue; + + if (pfn_to_nid(pfn) != nid) + continue; + + /* If the section is current section, it continues the loop */ + if (start_pfn == pfn) + continue; + + /* If we find valid section, we have nothing to do */ + return; + } + + /* The pgdat has no valid section */ + pgdat->node_start_pfn = 0; + pgdat->node_spanned_pages = 0; +} + +static void __remove_zone(struct zone *zone, unsigned long start_pfn) +{ + struct pglist_data *pgdat = zone->zone_pgdat; + int nr_pages = PAGES_PER_SECTION; + int zone_type; + unsigned long flags; + + zone_type = zone - pgdat->node_zones; + + pgdat_resize_lock(zone->zone_pgdat, &flags); + shrink_zone_span(zone, start_pfn, start_pfn + nr_pages); + shrink_pgdat_span(pgdat, start_pfn, start_pfn + nr_pages); + pgdat_resize_unlock(zone->zone_pgdat, &flags); +} + static int __remove_section(struct zone *zone, struct mem_section *ms) { unsigned long flags; struct pglist_data *pgdat = zone->zone_pgdat; + unsigned long start_pfn; + int scn_nr; int ret = -EINVAL; if (!valid_section(ms)) @@ -325,6 +528,10 @@ static int __remove_section(struct zone if (ret) return ret; + scn_nr = __section_nr(ms); + start_pfn = section_nr_to_pfn(scn_nr); + __remove_zone(zone, start_pfn); + pgdat_resize_lock(pgdat, &flags); sparse_remove_one_section(zone, ms); pgdat_resize_unlock(pgdat, &flags); -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html