RE: [PATCH 2/2] thp: support split page table lock

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> writes:

> Naoya Horiguchi wrote:
>> Thp related code also uses per process mm->page_table_lock now.
>> So making it fine-grained can provide better performance.
>> 
>> This patch makes thp support split page table lock by using page->ptl
>> of the pages storing "pmd_trans_huge" pmds.
>> 
>> Some functions like pmd_trans_huge_lock() and page_check_address_pmd()
>> are expected by their caller to pass back the pointer of ptl, so this
>> patch adds to those functions new arguments for that. Rather than that,
>> this patch gives only straightforward replacement.
>> 
>> ChangeLog v3:
>>  - fixed argument of huge_pmd_lockptr() in copy_huge_pmd()
>>  - added missing declaration of ptl in do_huge_pmd_anonymous_page()
>> 
>> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>
> Generally, looks good. Few notes:
>
> I believe you need to convert __pte_alloc() to new locking. Not sure about
> __pte_alloc_kernel().
> Have you check all rest mm->page_table_lock, that they shouldn't be
> converted to new locking?

May be we can have a CONFIG_DEBUG_VM version of pmd_populate that check 
check with assert_spin_locked ?


-aneesh

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