Hello,
>On Tue, 30 Sep 2014 17:02:01 +0800
>Baoquan He <bhe at redhat.com> wrote:
>
>> On 09/29/14 at 03:14pm, Michael Holzheu wrote:
>> > Implement is_vmalloc_addr() using /proc/iommem parsing to enable the new
>> > makedumpfile option "--mem-usage".
>> >
>> > Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com>
>>
>>
>> Hi Michael,
>>
>> This idea looks good to me. One question, should it be put in
>> arch/s390.c since this is only for s390? Then iomem_for_each_line() need
>> be declared in makedumpfile.h .
>>
>> If later it's needed by other arch, can be taken out to makedumpfile.c,
>> that should be better. Surely this is only my personal concern, if
>> Atsushi like to accept it, I am fine too.
>
>Hello Atsushi,
>
>What is your preference regarding this question?
>
>Michael
In the first place, this is_vmalloc_addr() for s390 isn't a good
implementation because it works only on 1st kernel due to the
dependence on /proc/iomem. is_vmalloc_addr_XXX() are general functions,
they can be called from any path besides --mem-usage.
I think the Michael's first idea below is better since it implements
is_real_addr() only for --mem-usage as a common function for all
architectures, it's explicit design.
>@@ -854,7 +854,7 @@ int get_kcore_dump_loads(void)
>
> for (i = 0; i < num_pt_loads; ++i) {
> struct pt_load_segment *p = &pt_loads[i];
>- if (is_vmalloc_addr(p->virt_start))
>+ if (!is_real_addr(p->virt_start))
> continue;
> loads++;
> }
However, this code will not work since the argument of is_real_addr()
must be physical address. Even unluckily, /proc/kcore's PT_LOAD looks
useless for VtoP converting because PhysAddr is always 0:
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
NOTE 0x00000000000002a8 0x0000000000000000 0x0000000000000000
0x0000000000000a84 0x0000000000000000 0
LOAD 0x00007fffff601000 0xffffffffff600000 0x0000000000000000
0x0000000000001000 0x0000000000001000 RWE 1000
LOAD 0x00007fff81001000 0xffffffff81000000 0x0000000000000000
0x0000000000a1b000 0x0000000000a1b000 RWE 1000
LOAD 0x0000490000001000 0xffffc90000000000 0x0000000000000000
0x00001fffffffffff 0x00001fffffffffff RWE 1000
LOAD 0x00007fffa0001000 0xffffffffa0000000 0x0000000000000000
0x000000005f000000 0x000000005f000000 RWE 1000
...
So the way using /proc/iomem seems inappropriate, we have to consider other
approaches (but I still don't have any good ideas...)
Thanks,
Atsushi Kumagai
