path: root/mm/nobootmem.c
diff options
authorJiang Liu <liuj97@gmail.com>2012-12-12 13:52:12 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-12 17:38:34 -0800
commit9feedc9d831e18ae6d0d15aa562e5e46ba53647b (patch)
treecb26ff54b0f02c4905772288b27f99b8b384ad6d /mm/nobootmem.c
parentc2d23f919bafcbc2259f5257d9a7d729802f0e3a (diff)
mm: introduce new field "managed_pages" to struct zone
Currently a zone's present_pages is calcuated as below, which is inaccurate and may cause trouble to memory hotplug. spanned_pages - absent_pages - memmap_pages - dma_reserve. During fixing bugs caused by inaccurate zone->present_pages, we found zone->present_pages has been abused. The field zone->present_pages may have different meanings in different contexts: 1) pages existing in a zone. 2) pages managed by the buddy system. For more discussions about the issue, please refer to: http://lkml.org/lkml/2012/11/5/866 https://patchwork.kernel.org/patch/1346751/ This patchset tries to introduce a new field named "managed_pages" to struct zone, which counts "pages managed by the buddy system". And revert zone->present_pages to count "physical pages existing in a zone", which also keep in consistence with pgdat->node_present_pages. We will set an initial value for zone->managed_pages in function free_area_init_core() and will adjust it later if the initial value is inaccurate. For DMA/normal zones, the initial value is set to: (spanned_pages - absent_pages - memmap_pages - dma_reserve) Later zone->managed_pages will be adjusted to the accurate value when the bootmem allocator frees all free pages to the buddy system in function free_all_bootmem_node() and free_all_bootmem(). The bootmem allocator doesn't touch highmem pages, so highmem zones' managed_pages is set to the accurate value "spanned_pages - absent_pages" in function free_area_init_core() and won't be updated anymore. This patch also adds a new field "managed_pages" to /proc/zoneinfo and sysrq showmem. [akpm@linux-foundation.org: small comment tweaks] Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Maciej Rutecki <maciej.rutecki@gmail.com> Tested-by: Chris Clayton <chris2553@googlemail.com> Cc: "Rafael J . Wysocki" <rjw@sisk.pl> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/nobootmem.c')
1 files changed, 22 insertions, 0 deletions
diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index bd82f6b31411..b8294fc03df8 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -137,6 +137,22 @@ unsigned long __init free_low_memory_core_early(int nodeid)
return count;
+static void reset_node_lowmem_managed_pages(pg_data_t *pgdat)
+ struct zone *z;
+ /*
+ * In free_area_init_core(), highmem zone's managed_pages is set to
+ * present_pages, and bootmem allocator doesn't allocate from highmem
+ * zones. So there's no need to recalculate managed_pages because all
+ * highmem pages will be managed by the buddy system. Here highmem
+ * zone also includes highmem movable zone.
+ */
+ for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
+ if (!is_highmem(z))
+ z->managed_pages = 0;
* free_all_bootmem_node - release a node's free pages to the buddy allocator
* @pgdat: node to be released
@@ -146,6 +162,7 @@ unsigned long __init free_low_memory_core_early(int nodeid)
unsigned long __init free_all_bootmem_node(pg_data_t *pgdat)
+ reset_node_lowmem_managed_pages(pgdat);
/* free_low_memory_core_early(MAX_NUMNODES) will be called later */
return 0;
@@ -158,6 +175,11 @@ unsigned long __init free_all_bootmem_node(pg_data_t *pgdat)
unsigned long __init free_all_bootmem(void)
+ struct pglist_data *pgdat;
+ for_each_online_pgdat(pgdat)
+ reset_node_lowmem_managed_pages(pgdat);
* We need to use MAX_NUMNODES instead of NODE_DATA(0)->node_id
* because in some case like Node0 doesn't have RAM installed