Re: [PATCH] mm: fix account pmd page to the process

From	zhong jiang <zhongjiang@huawei.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] mm: fix account pmd page to the process
Date	2016-06-17 13:20 +0200
Message-ID	<rKZYB-5P6-7@gated-at.bofh.it> (permalink)
References	<rKDEJ-7Kx-7@gated-at.bofh.it> <rKHIl-1K6-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 2016/6/16 23:42, Michal Hocko wrote:
> On Thu 16-06-16 19:36:11, zhongjiang wrote:
>> From: zhong jiang <zhongjiang@huawei.com>
>>
>> when a process acquire a pmd table shared by other process, we
>> increase the account to current process. otherwise, a race result
>> in other tasks have set the pud entry. so it no need to increase it.
>>
>> Signed-off-by: zhong jiang <zhongjiang@huawei.com>
>> ---
>>  mm/hugetlb.c | 5 ++---
>>  1 file changed, 2 insertions(+), 3 deletions(-)
>>
>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>> index 19d0d08..3b025c5 100644
>> --- a/mm/hugetlb.c
>> +++ b/mm/hugetlb.c
>> @@ -4189,10 +4189,9 @@ pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
>>  	if (pud_none(*pud)) {
>>  		pud_populate(mm, pud,
>>  				(pmd_t *)((unsigned long)spte & PAGE_MASK));
>> -	} else {
>> +	} else 
>>  		put_page(virt_to_page(spte));
>> -		mm_inc_nr_pmds(mm);
>> -	}
> The code is quite puzzling but is this correct? Shouldn't we rather do
> mm_dec_nr_pmds(mm) in that path to undo the previous inc?
  Yes, you are right. I will modify it in V2.
 
  Thanks
  zhongjiang
>
>> +
>>  	spin_unlock(ptl);
>>  out:
>>  	pte = (pte_t *)pmd_alloc(mm, pud, addr);
>> -- 
>> 1.8.3.1

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Re: [PATCH] mm: fix account pmd page to the process Michal Hocko <mhocko@kernel.org> - 2016-06-16 17:50 +0200
  Re: [PATCH] mm: fix account pmd page to the process Michal Hocko <mhocko@kernel.org> - 2016-06-16 17:50 +0200
    Re: [PATCH] mm: fix account pmd page to the process Mike Kravetz <mike.kravetz@oracle.com> - 2016-06-16 18:10 +0200
      Re: [PATCH] mm: fix account pmd page to the process Michal Hocko <mhocko@kernel.org> - 2016-06-16 18:40 +0200
        Re: [PATCH] mm: fix account pmd page to the process Mike Kravetz <mike.kravetz@oracle.com> - 2016-06-16 18:50 +0200
          Re: [PATCH] mm: fix account pmd page to the process "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-06-17 14:30 +0200
            Re: [PATCH] mm: fix account pmd page to the process Michal Hocko <mhocko@kernel.org> - 2016-06-17 15:10 +0200
              Re: [PATCH] mm: fix account pmd page to the process "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-06-17 16:30 +0200
            Re: [PATCH] mm: fix account pmd page to the process Mike Kravetz <mike.kravetz@oracle.com> - 2016-06-17 17:40 +0200
              Re: [PATCH] mm: fix account pmd page to the process zhong jiang <zhongjiang@huawei.com> - 2016-06-18 07:10 +0200
  Re: [PATCH] mm: fix account pmd page to the process zhong jiang <zhongjiang@huawei.com> - 2016-06-17 13:20 +0200

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