On Mon, Jul 2, 2012 at 7:54 PM, Jiang Liu <jiang.liu@xxxxxxxxxx> wrote: > On 2012-7-3 4:43, Yinghai Lu wrote: >> On Sun, Jul 1, 2012 at 7:01 PM, Jiang Liu <jiang.liu@xxxxxxxxxx> wrote: >>> Hi Yinghai, >>> The patch fails compilation as below: >>> mm/page_alloc.c:151: error: initializer element is not constant >>> mm/page_alloc.c:151: error: expected ‘,’ or ‘;’ before ‘__attribute__’ >>> >>> On IA64, HUGETLB_PAGE_ORDER has dependency on variable hpage_shift. >>> # define HUGETLB_PAGE_ORDER (HPAGE_SHIFT - PAGE_SHIFT) >>> # define HPAGE_SHIFT hpage_shift >>> >>> And hpage_shift could be changed by early parameter "hugepagesz". >>> So seems will still need to keep function set_pageblock_order(). >> >> ah, then use use _DEFAULT instead and later could update that in earlyparam. >> >> So attached -v2 should work. > Hi Yinghai, > > I'm afraid the v2 will break powerpc. Currently only IA64 and PowerPC > supports variable hugetlb size. > > HPAGE_SHIFT is a variable default to 0 on powerpc. But seems PowerPC > is doing something wrong here, according to it's mm initialization > sequence as below: > start_kernel() > setup_arch() > paging_init() > free_area_init_node() > set_pageblock_order() > refer to HPAGE_SHIFT (still 0) > init_rest() > do_initcalls() > hugetlbpage_init() > setup HPAGE_SHIFT > That means pageblock_order is always set to "MAX_ORDER - 1", not sure > whether this is intended. And it has the same issue as IA64 of wasting > memory if CONFIG_SPARSE is enabled. adding BenH, need to know if it is powerpc intended. > > So it would be better to keep function set_pageblock_order(), it will > fix the memory wasting on both IA64 and PowerPC. Should setup pageblock_order as early as possible to avoid confusing. Thanks Yinghai -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href