[PATCH V6 2/2] mm/debug: Add tests validating architecture page table helpers

[Anshuman Khandual]

On 10/15/2019 05:16 PM, Michal Hocko wrote:
> On Tue 15-10-19 14:51:42, Anshuman Khandual wrote:
>> This adds tests which will validate architecture page table helpers and
>> other accessors in their compliance with expected generic MM semantics.
>> This will help various architectures in validating changes to existing
>> page table helpers or addition of new ones.
>>
>> Test page table and memory pages creating it's entries at various level are
>> all allocated from system memory with required size and alignments. But if
>> memory pages with required size and alignment could not be allocated, then
>> all depending individual tests are just skipped afterwards. This test gets
>> called right after init_mm_internals() required for alloc_contig_range() to
>> work correctly.
>>
>> This gets build and run when CONFIG_DEBUG_VM_PGTABLE is selected along with
>> CONFIG_VM_DEBUG. Architectures willing to subscribe this test also need to
>> select CONFIG_ARCH_HAS_DEBUG_VM_PGTABLE which for now is limited to x86 and
>> arm64. Going forward, other architectures too can enable this after fixing
>> build or runtime problems (if any) with their page table helpers.
> 
> A highlevel description of tests and what they are testing for would be
> really appreciated. Who wants to run these tests and why/when? What kind
> of bugs would get detected? In short why do we really need/want this
> code in the tree?

Sure, will do.