From: Xishi Qiu <[email protected]>
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 <[email protected]>
Signed-off-by: Jiang Liu <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: Yinghai Lu <[email protected]>
Cc: KAMEZAWA Hiroyuki <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Keping Chen <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
mm/internal.h | 2 ++
mm/page_alloc.c | 4 ++--
mm/sparse.c | 3 +++
3 files changed, 7 insertions(+), 2 deletions(-)
diff -puN mm/internal.h~mm-setup-pageblock_order-before-its-used-by-sparsemem
mm/internal.h
--- a/mm/internal.h~mm-setup-pageblock_order-before-its-used-by-sparsemem
+++ a/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 -puN mm/page_alloc.c~mm-setup-pageblock_order-before-its-used-by-sparsemem
mm/page_alloc.c
--- a/mm/page_alloc.c~mm-setup-pageblock_order-before-its-used-by-sparsemem
+++ a/mm/page_alloc.c
@@ -4304,7 +4304,7 @@ static inline void setup_usemap(struct p
#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_
* 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 -puN mm/sparse.c~mm-setup-pageblock_order-before-its-used-by-sparsemem
mm/sparse.c
--- a/mm/sparse.c~mm-setup-pageblock_order-before-its-used-by-sparsemem
+++ a/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)
_
--
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