From 7f1290f2f2a4d2c3f1b7ce8e87256e052ca23125 Mon Sep 17 00:00:00 2001 From: Jianguo Wu Date: Mon, 8 Oct 2012 16:33:06 -0700 Subject: mm: fix-up zone present pages I think zone->present_pages indicates pages that buddy system can management, it should be: zone->present_pages = spanned pages - absent pages - bootmem pages, but is now: zone->present_pages = spanned pages - absent pages - memmap pages. spanned pages: total size, including holes. absent pages: holes. bootmem pages: pages used in system boot, managed by bootmem allocator. memmap pages: pages used by page structs. This may cause zone->present_pages less than it should be. For example, numa node 1 has ZONE_NORMAL and ZONE_MOVABLE, it's memmap and other bootmem will be allocated from ZONE_MOVABLE, so ZONE_NORMAL's present_pages should be spanned pages - absent pages, but now it also minus memmap pages(free_area_init_core), which are actually allocated from ZONE_MOVABLE. When offlining all memory of a zone, this will cause zone->present_pages less than 0, because present_pages is unsigned long type, it is actually a very large integer, it indirectly caused zone->watermark[WMARK_MIN] becomes a large integer(setup_per_zone_wmarks()), than cause totalreserve_pages become a large integer(calculate_totalreserve_pages()), and finally cause memory allocating failure when fork process(__vm_enough_memory()). [root@localhost ~]# dmesg -bash: fork: Cannot allocate memory I think the bug described in http://marc.info/?l=linux-mm&m=134502182714186&w=2 is also caused by wrong zone present pages. This patch intends to fix-up zone->present_pages when memory are freed to buddy system on x86_64 and IA64 platforms. Signed-off-by: Jianguo Wu Signed-off-by: Jiang Liu Reported-by: Petr Tesarik Tested-by: Petr Tesarik Cc: "Luck, Tony" Cc: Mel Gorman Cc: Yinghai Lu Cc: Minchan Kim Cc: Johannes Weiner Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/bootmem.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'mm/bootmem.c') diff --git a/mm/bootmem.c b/mm/bootmem.c index f468185b3b28..434be4ae7a04 100644 --- a/mm/bootmem.c +++ b/mm/bootmem.c @@ -198,6 +198,8 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata) int order = ilog2(BITS_PER_LONG); __free_pages_bootmem(pfn_to_page(start), order); + fixup_zone_present_pages(page_to_nid(pfn_to_page(start)), + start, start + BITS_PER_LONG); count += BITS_PER_LONG; start += BITS_PER_LONG; } else { @@ -208,6 +210,9 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata) if (vec & 1) { page = pfn_to_page(start + off); __free_pages_bootmem(page, 0); + fixup_zone_present_pages( + page_to_nid(page), + start + off, start + off + 1); count++; } vec >>= 1; @@ -221,8 +226,11 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata) pages = bdata->node_low_pfn - bdata->node_min_pfn; pages = bootmem_bootmap_pages(pages); count += pages; - while (pages--) + while (pages--) { + fixup_zone_present_pages(page_to_nid(page), + page_to_pfn(page), page_to_pfn(page) + 1); __free_pages_bootmem(page++, 0); + } bdebug("nid=%td released=%lx\n", bdata - bootmem_node_data, count); -- cgit v1.2.3