On 04/29/2020 10:27 PM, HAGIO KAZUHITO(萩尾 一仁) wrote:
> Hi Pingfan,
>
>> -----Original Message-----
>> Hi Kazu and Cascardo,
>>
>> I encounter a weird problem when running makedumpfile on a s390 machine.
>>
>> Our production kernel uses extreme sparse memory model, and has the
>> following:
>>
>> in mm/sparse.c
>>
>> #ifdef CONFIG_SPARSEMEM_EXTREME
>> struct mem_section **mem_section;
>> #else
>> struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
>> ____cacheline_internodealigned_in_smp;
>> #endif
>>
>> So in makedumpfile.c, get_mem_section(), it got a failed result when the
>> first call site to validate_mem_section(), then it should success at the
>> second call site to validate_mem_section(), which is inside if
>> (is_sparsemem_extreme()) condition.
>
> I think your production kernel should have kernel commit a0b1280368d1
> ("kdump: write correct address of mem_section into vmcoreinfo"), so the
> first call should return TRUE and the second one should return FALSE.
Yes, it is.
>
>>
>> But the actual result is not like expected.
>>
>> After introducing
>> commit e113f1c974c820f9633dc0073eda525d7575f365 [PATCH] cope with
>> not-present mem section
>>
>> I got two successful calls to validate_mem_section(), and finally failed
>> at the condition
>> ret = symbol_valid ^ pointer_valid;
>> if (!ret) {
>> ERRMSG("Could not validate mem_section.\n");
>> }
>>
>>
>> Do you have any idea?
>
> Presumably this will be what I expected that it might be possible.
> I can apply the patch below this time, what about this?
> https://github.com/k-hagio/makedumpfile-old/commit/ce883df3864a5744ac0f1eff47de06b5074edb5f.patch
looks good.
>
> or, we can also investigate why the second call returns TRUE, and
> fix the conditions in the validate_mem_section()..
This is due to the relaxed condition check after applying my commit
commit e113f1c974("[PATCH] cope with not-present mem section")
diff --git a/makedumpfile.c b/makedumpfile.c
index ae7336a..607e07f 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -3406,8 +3406,6 @@ section_mem_map_addr(unsigned long addr, unsigned
long *map_mask)
map = ULONG(mem_section + OFFSET(mem_section.section_mem_map));
mask = SECTION_MAP_MASK;
*map_mask = map & ~mask;
- if (map == 0x0)
- *map_mask |= SECTION_MARKED_PRESENT;
map &= mask;
free(mem_section);
@@ -3453,10 +3451,8 @@ validate_mem_section(unsigned long *mem_sec,
mem_map = NOT_MEMMAP_ADDR;
} else {
mem_map = section_mem_map_addr(section, &map_mask);
+ /* for either no mem_map or hot-removed */
if (!(map_mask & SECTION_MARKED_PRESENT)) {
- return FALSE; ------> a strict check
- }
- if (mem_map == 0) {
mem_map = NOT_MEMMAP_ADDR;
} else {
mem_map = sparse_decode_mem_map(mem_map,
Before my patch, it return FALSE for any non NULL value without
SECTION_MARKED_PRESENT. But my patch relaxes the restriction and
consider it as hot-removed mem_section and keeps the parsing on.
Thanks,
Pingfan
>
> Thanks,
> Kazu
> _______________________________________________
> kexec mailing list
> kexec@xxxxxxxxxxxxxxxxxxx
> http://lists.infradead.org/mailman/listinfo/kexec
>
_______________________________________________
kexec mailing list
kexec@xxxxxxxxxxxxxxxxxxx
http://lists.infradead.org/mailman/listinfo/kexec
