On Fri, Mar 16, 2012 at 11:02:16AM +0800, Dave Young wrote:
> crashkernel reservation need know the total memory size. Current get_total_mem
> simply use max_pfn - min_low_pfn. It is wrong because it will including
> memory holes in the middle.
>
> Especially for kvm guest with memory > 0xe0000000, there's below in qemu code:
> qemu split memory as below:
> if (ram_size >= 0xe0000000 ) {
> above_4g_mem_size = ram_size - 0xe0000000;
> below_4g_mem_size = 0xe0000000;
> } else {
> below_4g_mem_size = ram_size;
> }
> So for 4G mem guest, seabios will insert a 512M usable region beyond of 4G.
> Thus in above case max_pfn - min_low_pfn will be more than original memsize.
>
> Fixing this issue by using memblock_phys_mem_size() to get the total memsize.
>
> [v1 -> v2]: refresh the patch based on latest linus tree
>
> Signed-off-by: Dave Young <dyoung at redhat.com>
> Reviewed-by: WANG Cong <xiyou.wangcong at gmail.com>
Reviewed-by: Simon Horman <horms at verge.net.au>
Andrew, can you pick this up?
It has been floating around without objections for a week now.
> ---
> arch/x86/kernel/setup.c | 11 +----------
> 1 file changed, 1 insertion(+), 10 deletions(-)
>
> --- linux-2.6.orig/arch/x86/kernel/setup.c 2012-03-04 03:46:35.000000000 +0800
> +++ linux-2.6/arch/x86/kernel/setup.c 2012-03-10 12:44:58.133300788 +0800
> @@ -509,15 +509,6 @@ static void __init memblock_x86_reserve_
>
> #ifdef CONFIG_KEXEC
>
> -static inline unsigned long long get_total_mem(void)
> -{
> - unsigned long long total;
> -
> - total = max_pfn - min_low_pfn;
> -
> - return total << PAGE_SHIFT;
> -}
> -
> /*
> * Keep the crash kernel below this limit. On 32 bits earlier kernels
> * would limit the kernel to the low 512 MiB due to mapping restrictions.
> @@ -536,7 +527,7 @@ static void __init reserve_crashkernel(v
> unsigned long long crash_size, crash_base;
> int ret;
>
> - total_mem = get_total_mem();
> + total_mem = memblock_phys_mem_size();
>
> ret = parse_crashkernel(boot_command_line, total_mem,
> &crash_size, &crash_base);
> --
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