From: Michael Holzheu <holzheu@xxxxxxxxxxxxxxxxxx>
Subject: [PATCH 2/2] makedumpfile: Use max_pfn from mem_map array
Date: Tue, 25 Mar 2014 17:14:20 +0100
> There are dump mechansims like s390 stand-alond dump or KVM virsh dump
> that write the physical memory of a machine and are not aware of the
> dumped operating system. For those dump mechanisms it can happen
> that for the Linux kernel of the dumped system the "mem=" kernel
> parameter has been specified. In this case max_mapnr that makedumpfile
> gets from the ELF header can be bigger than the maximum page frame number
> used by the dumped Linux kernel.
>
> With this patch makedumpfile gets the maximum page frame number from
> the mem_map array and adjusts info->max_mapnr if this value is smaller
> than the value calculated from the ELF header.
>
> Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com>
> ---
> makedumpfile.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> --- a/makedumpfile.c
> +++ b/makedumpfile.c
> @@ -2829,7 +2829,8 @@ get_mem_map_without_mm(void)
> int
> get_mem_map(void)
> {
> - int ret;
> + unsigned long max_pfn = 0;
> + int ret, i;
Please define max_pfn as unsigned long long.
And for i,
>
> switch (get_mem_type()) {
> case SPARSEMEM:
> @@ -2861,6 +2862,17 @@ get_mem_map(void)
> ret = FALSE;
> break;
> }
> + /*
> + * Adjust "max_mapnr" for the case that Linux uses less memory
> + * than is dumped. For example when "mem=" has been used for the
> + * dumped system.
> + */
> + for (i = 0; i < info->num_mem_map; i++) {
info->num_mem_map is defined as unsigned int. I guess some warning
about comparison with different signedness occurs.
> + if (info->mem_map_data[i].mem_map == NOT_MEMMAP_ADDR)
> + continue;
> + max_pfn = MAX(max_pfn, info->mem_map_data[i].pfn_end);
> + }
> + info->max_mapnr = MIN(info->max_mapnr, max_pfn);
> return ret;
> }
>
>
Thanks.
HATAYAMA, Daisuke
