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/*
* linux/mm/mmzone.c
*
* management codes for pgdats and zones.
*/
#include <linux/stddef.h>
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/module.h>
struct pglist_data *first_online_pgdat(void)
{
return NODE_DATA(first_online_node);
}
struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
{
int nid = next_online_node(pgdat->node_id);
if (nid == MAX_NUMNODES)
return NULL;
return NODE_DATA(nid);
}
/*
* next_zone - helper magic for for_each_zone()
*/
struct zone *next_zone(struct zone *zone)
{
pg_data_t *pgdat = zone->zone_pgdat;
if (zone < pgdat->node_zones + MAX_NR_ZONES - 1)
zone++;
else {
pgdat = next_online_pgdat(pgdat);
if (pgdat)
zone = pgdat->node_zones;
else
zone = NULL;
}
return zone;
}
static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
{
#ifdef CONFIG_NUMA
return node_isset(zonelist_node_idx(zref), *nodes);
#else
return 1;
#endif /* CONFIG_NUMA */
}
/* Returns the next zone at or below highest_zoneidx in a zonelist */
struct zoneref *next_zones_zonelist(struct zoneref *z,
enum zone_type highest_zoneidx,
nodemask_t *nodes,
struct zone **zone)
{
/*
* Find the next suitable zone to use for the allocation.
* Only filter based on nodemask if it's set
*/
if (likely(nodes == NULL))
while (zonelist_zone_idx(z) > highest_zoneidx)
z++;
else
while (zonelist_zone_idx(z) > highest_zoneidx ||
(z->zone && !zref_in_nodemask(z, nodes)))
z++;
*zone = zonelist_zone(z);
return z;
}
#ifdef CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
int memmap_valid_within(unsigned long pfn,
struct page *page, struct zone *zone)
{
if (page_to_pfn(page) != pfn)
return 0;
if (page_zone(page) != zone)
return 0;
return 1;
}
#endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
#ifdef CONFIG_SMP
/* Called when a more accurate view of NR_FREE_PAGES is needed */
unsigned long zone_nr_free_pages(struct zone *zone)
{
unsigned long nr_free_pages = zone_page_state(zone, NR_FREE_PAGES);
/*
* While kswapd is awake, it is considered the zone is under some
* memory pressure. Under pressure, there is a risk that
* per-cpu-counter-drift will allow the min watermark to be breached
* potentially causing a live-lock. While kswapd is awake and
* free pages are low, get a better estimate for free pages
*/
if (nr_free_pages < zone->percpu_drift_mark &&
!waitqueue_active(&zone->zone_pgdat->kswapd_wait))
return zone_page_state_snapshot(zone, NR_FREE_PAGES);
return nr_free_pages;
}
#endif /* CONFIG_SMP */
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