[PATCH 2/2] makedumpfile: Use max_pfn from mem_map array

[Atsushi Kumagai]

Hello Michael,

>On Wed, 26 Mar 2014 10:55:07 +0100 (a/T)
>HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com> wrote:
>
>> From: Michael Holzheu <holzheu at linux.vnet.ibm.com>
>> Subject: [PATCH 2/2] makedumpfile: Use max_pfn from mem_map array
>> Date: Tue, 25 Mar 2014 17:14:20 +0100
>
>[snip]
>
>> > 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.
>
>Ok done.
>
>>
>> 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.
>
>Ah ok...
>
>With the default CFLAGS for makedumpfile-1.5.5 tarball I do not get
>any warning. When I add "-W" to CFLAGS, I get lots of warnings
>including the one you mentioned.
>
>Here the fixed patch:

Thanks, I'll merge the fixed version into v1.5.6.


Atsushi Kumagai

>---
>[PATCH 2/2] makedumpfile: Use max_pfn from mem_map array
>
>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 |   13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
>--- a/makedumpfile.c
>+++ b/makedumpfile.c
>@@ -2829,6 +2829,8 @@ get_mem_map_without_mm(void)
> int
> get_mem_map(void)
> {
>+	unsigned long long max_pfn = 0;
>+	unsigned int i;
> 	int ret;
>
> 	switch (get_mem_type()) {
>@@ -2861,6 +2863,17 @@ 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++) {
>+		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;
> }
>
>
>
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