/* * 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 */