From ca57df79d4f64e1a4886606af4289d40636189c5 Mon Sep 17 00:00:00 2001 From: Xishi Qiu Date: Tue, 31 Jul 2012 16:43:19 -0700 Subject: mm: setup pageblock_order before it's used by sparsemem On architectures with CONFIG_HUGETLB_PAGE_SIZE_VARIABLE set, such as Itanium, pageblock_order is a variable with default value of 0. It's set to the right value by set_pageblock_order() in function free_area_init_core(). But pageblock_order may be used by sparse_init() before free_area_init_core() is called along path: sparse_init() ->sparse_early_usemaps_alloc_node() ->usemap_size() ->SECTION_BLOCKFLAGS_BITS ->((1UL << (PFN_SECTION_SHIFT - pageblock_order)) * NR_PAGEBLOCK_BITS) The uninitialized pageblock_size will cause memory wasting because usemap_size() returns a much bigger value then it's really needed. For example, on an Itanium platform, sparse_init() pageblock_order=0 usemap_size=24576 free_area_init_core() before pageblock_order=0, usemap_size=24576 free_area_init_core() after pageblock_order=12, usemap_size=8 That means 24K memory has been wasted for each section, so fix it by calling set_pageblock_order() from sparse_init(). Signed-off-by: Xishi Qiu Signed-off-by: Jiang Liu Cc: Tony Luck Cc: Yinghai Lu Cc: KAMEZAWA Hiroyuki Cc: Benjamin Herrenschmidt Cc: KOSAKI Motohiro Cc: David Rientjes Cc: Keping Chen Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/internal.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'mm/internal.h') diff --git a/mm/internal.h b/mm/internal.h index da6b9b2ed3fc..3314f79d775a 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -353,3 +353,5 @@ extern u32 hwpoison_filter_enable; extern unsigned long vm_mmap_pgoff(struct file *, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); + +extern void set_pageblock_order(void); -- cgit v1.2.3