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SubjectRe: [PATCH 27/46] x86, mm: Add alloc_low_pages(num)
On Mon, 12 Nov 2012, Yinghai Lu wrote:
> 32bit kmap mapping needs pages to be used for low to high.
> At this point those pages are still from pgt_buf_* from BRK, so it is
> ok now.
> But we want to move early_ioremap_page_table_range_init() out of
> init_memory_mapping() and only call it one time later, that will
> make page_table_range_init/page_table_kmap_check/alloc_low_page to
> use memblock to get page.
>
> memblock allocation for pages are from high to low.
> So will get panic from page_table_kmap_check() that has BUG_ON to do
> ordering checking.
>
> This patch add alloc_low_pages to make it possible to allocate serveral
> pages at first, and hand out pages one by one from low to high.
>
> -v2: add one line comment about xen requirements.

where is it?

> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
> arch/x86/mm/init.c | 33 +++++++++++++++++++++------------
> arch/x86/mm/mm_internal.h | 6 +++++-
> 2 files changed, 26 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index 9d51af72..f5e0120 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -25,36 +25,45 @@ unsigned long __meminitdata pgt_buf_top;
>
> static unsigned long min_pfn_mapped;
>
> -__ref void *alloc_low_page(void)
> +__ref void *alloc_low_pages(unsigned int num)
> {
> unsigned long pfn;
> - void *adr;
> + int i;
>
> #ifdef CONFIG_X86_64
> if (after_bootmem) {
> - adr = (void *)get_zeroed_page(GFP_ATOMIC | __GFP_NOTRACK);
> + unsigned int order;
>
> - return adr;
> + order = get_order((unsigned long)num << PAGE_SHIFT);
> + return (void *)__get_free_pages(GFP_ATOMIC | __GFP_NOTRACK |
> + __GFP_ZERO, order);
> }
> #endif
>
> - if ((pgt_buf_end + 1) >= pgt_buf_top) {
> + if ((pgt_buf_end + num) >= pgt_buf_top) {
> unsigned long ret;
> if (min_pfn_mapped >= max_pfn_mapped)
> panic("alloc_low_page: ran out of memory");
> ret = memblock_find_in_range(min_pfn_mapped << PAGE_SHIFT,
> max_pfn_mapped << PAGE_SHIFT,
> - PAGE_SIZE, PAGE_SIZE);
> + PAGE_SIZE * num , PAGE_SIZE);
> if (!ret)
> panic("alloc_low_page: can not alloc memory");
> - memblock_reserve(ret, PAGE_SIZE);
> + memblock_reserve(ret, PAGE_SIZE * num);
> pfn = ret >> PAGE_SHIFT;
> - } else
> - pfn = pgt_buf_end++;
> + } else {
> + pfn = pgt_buf_end;
> + pgt_buf_end += num;
> + }
> +
> + for (i = 0; i < num; i++) {
> + void *adr;
> +
> + adr = __va((pfn + i) << PAGE_SHIFT);
> + clear_page(adr);
> + }
>
> - adr = __va(pfn * PAGE_SIZE);
> - clear_page(adr);
> - return adr;
> + return __va(pfn << PAGE_SHIFT);
> }
>
> /* need 4 4k for initial PMD_SIZE, 4k for 0-ISA_END_ADDRESS */
> diff --git a/arch/x86/mm/mm_internal.h b/arch/x86/mm/mm_internal.h
> index b3f993a..7e3b88e 100644
> --- a/arch/x86/mm/mm_internal.h
> +++ b/arch/x86/mm/mm_internal.h
> @@ -1,6 +1,10 @@
> #ifndef __X86_MM_INTERNAL_H
> #define __X86_MM_INTERNAL_H
>
> -void *alloc_low_page(void);
> +void *alloc_low_pages(unsigned int num);
> +static inline void *alloc_low_page(void)
> +{
> + return alloc_low_pages(1);
> +}
>
> #endif /* __X86_MM_INTERNAL_H */
> --
> 1.7.7
>


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