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![Mel Gorman](/assets/img/avatar_default.png)
The iterator for_each_zone_zonelist() uses a struct zoneref *z cursor when scanning zonelists to keep track of where in the zonelist it is. The zoneref that is returned corresponds to the the next zone that is to be scanned, not the current one. It was intended to be treated as an opaque list. When the page allocator is scanning a zonelist, it marks elements in the zonelist corresponding to zones that are temporarily full. As the zonelist is being updated, it uses the cursor here; if (NUMA_BUILD) zlc_mark_zone_full(zonelist, z); This is intended to prevent rescanning in the near future but the zoneref cursor does not correspond to the zone that has been found to be full. This is an easy misunderstanding to make so this patch corrects the problem by changing zoneref cursor to be the current zone being scanned instead of the next one. Signed-off-by: Mel Gorman <mel@csn.ul.ie> Cc: Andy Whitcroft <apw@shadowen.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: <stable@kernel.org> [2.6.26.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
74 lines
1.5 KiB
C
74 lines
1.5 KiB
C
/*
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* linux/mm/mmzone.c
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*
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* management codes for pgdats and zones.
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*/
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#include <linux/stddef.h>
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#include <linux/mmzone.h>
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#include <linux/module.h>
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struct pglist_data *first_online_pgdat(void)
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{
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return NODE_DATA(first_online_node);
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}
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struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
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{
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int nid = next_online_node(pgdat->node_id);
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if (nid == MAX_NUMNODES)
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return NULL;
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return NODE_DATA(nid);
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}
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/*
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* next_zone - helper magic for for_each_zone()
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*/
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struct zone *next_zone(struct zone *zone)
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{
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pg_data_t *pgdat = zone->zone_pgdat;
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if (zone < pgdat->node_zones + MAX_NR_ZONES - 1)
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zone++;
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else {
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pgdat = next_online_pgdat(pgdat);
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if (pgdat)
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zone = pgdat->node_zones;
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else
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zone = NULL;
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}
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return zone;
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}
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static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
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{
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#ifdef CONFIG_NUMA
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return node_isset(zonelist_node_idx(zref), *nodes);
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#else
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return 1;
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#endif /* CONFIG_NUMA */
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}
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/* Returns the next zone at or below highest_zoneidx in a zonelist */
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struct zoneref *next_zones_zonelist(struct zoneref *z,
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enum zone_type highest_zoneidx,
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nodemask_t *nodes,
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struct zone **zone)
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{
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/*
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* Find the next suitable zone to use for the allocation.
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* Only filter based on nodemask if it's set
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*/
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if (likely(nodes == NULL))
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while (zonelist_zone_idx(z) > highest_zoneidx)
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z++;
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else
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while (zonelist_zone_idx(z) > highest_zoneidx ||
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(z->zone && !zref_in_nodemask(z, nodes)))
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z++;
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*zone = zonelist_zone(z);
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return z;
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}
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