Re: [PATCH v2 10/12] memory-hotplug: memory_hotplug: clear zone when removing the memory

Wen Congyang
2012-10-30T01:44:48Z

At 10/29/2012 11:34 PM, Jianguo Wu Wrote:
> On 2012/10/23 18:30, wency@cn.fujitsu.com wrote:
>> From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>>
>> 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@google.com>
>> CC: Jiang Liu <liuj97@gmail.com>
>> CC: Len Brown <len.brown@intel.com>
>> CC: Christoph Lameter <cl@linux.com>
>> Cc: Minchan Kim <minchan.kim@gmail.com>
>> CC: Andrew Morton <akpm@linux-foundation.org>
>> CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>> ---
>> mm/memory_hotplug.c | 207 +++++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 files changed, 207 insertions(+), 0 deletions(-)
>>
>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>> index 03153cf..55a228d 100644
>> --- a/mm/memory_hotplug.c
>> +++ b/mm/memory_hotplug.c
>> @@ -312,10 +312,213 @@ static int __meminit __add_section(int nid, struct zone *zone,
>> 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)
>
> if (unlikely(pfn_to_nid(start_pfn) != nid))

Thanks for pointing it out. I will fix it soon.

Wen Congyang

>
>> + 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)
>
> 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 *zone, struct mem_section *ms)
>> 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);
>>
>
>