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/memory_hotplug.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'mm/memory_hotplug.c') diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index f9ac0955e10a..ce690a911f1b 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -106,6 +106,7 @@ static void get_page_bootmem(unsigned long info, struct page *page, void __ref put_page_bootmem(struct page *page) { unsigned long type; + struct zone *zone; type = (unsigned long) page->lru.next; BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE || @@ -116,6 +117,12 @@ void __ref put_page_bootmem(struct page *page) set_page_private(page, 0); INIT_LIST_HEAD(&page->lru); __free_pages_bootmem(page, 0); + + zone = page_zone(page); + zone_span_writelock(zone); + zone->present_pages++; + zone_span_writeunlock(zone); + totalram_pages++; } } -- cgit v1.2.1