From ca57df79d4f64e1a4886606af4289d40636189c5 Mon Sep 17 00:00:00 2001 From: Xishi Qiu Date: Tue, 31 Jul 2012 16:43:19 -0700 Subject: [PATCH] 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 ++ mm/page_alloc.c | 4 ++-- mm/sparse.c | 3 +++ 3 files changed, 7 insertions(+), 2 deletions(-) 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); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 94fc475c3f94..6c7e3bd93a85 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4304,7 +4304,7 @@ static inline void setup_usemap(struct pglist_data *pgdat, #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE /* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */ -static inline void __init set_pageblock_order(void) +void __init set_pageblock_order(void) { unsigned int order; @@ -4332,7 +4332,7 @@ static inline void __init set_pageblock_order(void) * include/linux/pageblock-flags.h for the values of pageblock_order based on * the kernel config */ -static inline void set_pageblock_order(void) +void __init set_pageblock_order(void) { } diff --git a/mm/sparse.c b/mm/sparse.c index c7bb952400c8..950981fd07c5 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -493,6 +493,9 @@ void __init sparse_init(void) struct page **map_map; #endif + /* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */ + set_pageblock_order(); + /* * map is using big page (aka 2M in x86 64 bit) * usemap is less one page (aka 24 bytes) -- 2.20.1