From 9feedc9d831e18ae6d0d15aa562e5e46ba53647b Mon Sep 17 00:00:00 2001 From: Jiang Liu Date: Wed, 12 Dec 2012 13:52:12 -0800 Subject: 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 Cc: Wen Congyang Cc: David Rientjes Cc: Maciej Rutecki Tested-by: Chris Clayton Cc: "Rafael J . Wysocki" Cc: Mel Gorman Cc: Minchan Kim Cc: KAMEZAWA Hiroyuki Cc: Michal Hocko Cc: Jianguo Wu Cc: Johannes Weiner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/bootmem.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'mm/bootmem.c') diff --git a/mm/bootmem.c b/mm/bootmem.c index 26d057a..19262ac 100644 --- a/mm/bootmem.c +++ b/mm/bootmem.c @@ -229,6 +229,22 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata) 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 @@ -238,6 +254,7 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata) unsigned long __init free_all_bootmem_node(pg_data_t *pgdat) { register_page_bootmem_info_node(pgdat); + reset_node_lowmem_managed_pages(pgdat); return free_all_bootmem_core(pgdat->bdata); } @@ -250,6 +267,10 @@ unsigned long __init free_all_bootmem(void) { unsigned long total_pages = 0; bootmem_data_t *bdata; + struct pglist_data *pgdat; + + for_each_online_pgdat(pgdat) + reset_node_lowmem_managed_pages(pgdat); list_for_each_entry(bdata, &bdata_list, list) total_pages += free_all_bootmem_core(bdata); -- cgit v1.1