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/nobootmem.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'mm/nobootmem.c') diff --git a/mm/nobootmem.c b/mm/nobootmem.c index bd82f6b31411..714d5d650470 100644 --- a/mm/nobootmem.c +++ b/mm/nobootmem.c @@ -116,6 +116,8 @@ static unsigned long __init __free_memory_core(phys_addr_t start, return 0; __free_pages_memory(start_pfn, end_pfn); + fixup_zone_present_pages(pfn_to_nid(start >> PAGE_SHIFT), + start_pfn, end_pfn); return end_pfn - start_pfn; } @@ -126,6 +128,7 @@ unsigned long __init free_low_memory_core_early(int nodeid) phys_addr_t start, end, size; u64 i; + reset_zone_present_pages(); for_each_free_mem_range(i, MAX_NUMNODES, &start, &end, NULL) count += __free_memory_core(start, end); -- cgit v1.2.3