path: root/mm/sparse.c
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authorXishi Qiu <qiuxishi@huawei.com>2012-07-31 16:43:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-07-31 18:42:43 -0700
commitca57df79d4f64e1a4886606af4289d40636189c5 (patch)
treee56d0411e552dec588778caaaa5e7d9885dd1a2c /mm/sparse.c
parent51a07e50b230d14e1b8bef50d66655d003fa006c (diff)
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 <qiuxishi@huawei.com> Signed-off-by: Jiang Liu <liuj97@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: David Rientjes <rientjes@google.com> Cc: Keping Chen <chenkeping@huawei.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/sparse.c')
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/sparse.c b/mm/sparse.c
index c7bb952400c..950981fd07c 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -493,6 +493,9 @@ void __init sparse_init(void)
struct page **map_map;
+ /* 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)