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SubjectRe: [PATCH v7u1 01/31] x86, mm: Fix page table early allocation offset checking
On Fri, 4 Jan 2013, Yinghai Lu wrote:
> During debugging loading kernel above 4G, found one page if is not used
> in BRK with early page allocation.
>
> pgt_buf_top is address that can not be used, so should check if that new
> end is above that top, otherwise last page will not be used.
>
> Fix that checking and also add print out for every allocation from BRK.
>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>

Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>


> arch/x86/mm/init.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index 6f85de8..c4293cf 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -47,7 +47,7 @@ __ref void *alloc_low_pages(unsigned int num)
> __GFP_ZERO, order);
> }
>
> - if ((pgt_buf_end + num) >= 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");
> @@ -61,6 +61,8 @@ __ref void *alloc_low_pages(unsigned int num)
> } else {
> pfn = pgt_buf_end;
> pgt_buf_end += num;
> + printk(KERN_DEBUG "BRK [%#010lx, %#010lx] PGTABLE\n",
> + pfn << PAGE_SHIFT, (pgt_buf_end << PAGE_SHIFT) - 1);
> }
>
> for (i = 0; i < num; i++) {
> --
> 1.7.10.4
>
> --
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