Re: [PATCH 2/6] mm/hwpoison: don't need to hold compound lock for hugetlbfs page

[Wanpeng Li <liwanp@linux.vnet.ibm.com>]

Hi Naoya,
On Thu, Aug 22, 2013 at 11:52:52AM -0400, Naoya Horiguchi wrote:
>On Thu, Aug 22, 2013 at 05:48:23PM +0800, Wanpeng Li wrote:
>> compound lock is introduced by commit e9da73d67("thp: compound_lock."), 
>> it is used to serialize put_page against __split_huge_page_refcount(). 
>> In addition, transparent hugepages will be splitted in hwpoison handler 
>> and just one subpage will be poisoned. There is unnecessary to hold 
>> compound lock for hugetlbfs page. This patch replace compound_trans_order 
>> by compond_order in the place where the page is hugetlbfs page.
>> 
>> Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
>> ---
>>  mm/memory-failure.c | 10 +++++-----
>>  1 file changed, 5 insertions(+), 5 deletions(-)
>> 
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index 2c13aa7..5092e06 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -206,7 +206,7 @@ static int kill_proc(struct task_struct *t, unsigned long addr, int trapno,
>>  #ifdef __ARCH_SI_TRAPNO
>>  	si.si_trapno = trapno;
>>  #endif
>> -	si.si_addr_lsb = compound_trans_order(compound_head(page)) + PAGE_SHIFT;
>> +	si.si_addr_lsb = compound_order(compound_head(page)) + PAGE_SHIFT;
>>  
>>  	if ((flags & MF_ACTION_REQUIRED) && t == current) {
>>  		si.si_code = BUS_MCEERR_AR;
>> @@ -983,7 +983,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
>>  static void set_page_hwpoison_huge_page(struct page *hpage)
>>  {
>>  	int i;
>> -	int nr_pages = 1 << compound_trans_order(hpage);
>> +	int nr_pages = 1 << compound_order(hpage);
>>  	for (i = 0; i < nr_pages; i++)
>>  		SetPageHWPoison(hpage + i);
>>  }
>> @@ -991,7 +991,7 @@ static void set_page_hwpoison_huge_page(struct page *hpage)
>>  static void clear_page_hwpoison_huge_page(struct page *hpage)
>>  {
>>  	int i;
>> -	int nr_pages = 1 << compound_trans_order(hpage);
>> +	int nr_pages = 1 << compound_order(hpage);
>>  	for (i = 0; i < nr_pages; i++)
>>  		ClearPageHWPoison(hpage + i);
>>  }
>> @@ -1491,7 +1491,7 @@ static int soft_offline_huge_page(struct page *page, int flags)
>>  	} else {
>>  		set_page_hwpoison_huge_page(hpage);
>>  		dequeue_hwpoisoned_huge_page(hpage);
>> -		atomic_long_add(1 << compound_trans_order(hpage),
>> +		atomic_long_add(1 << compound_order(hpage),
>>  				&num_poisoned_pages);
>>  	}
>>  	return ret;
>> @@ -1551,7 +1551,7 @@ int soft_offline_page(struct page *page, int flags)
>>  		if (PageHuge(page)) {
>>  			set_page_hwpoison_huge_page(hpage);
>>  			dequeue_hwpoisoned_huge_page(hpage);
>> -			atomic_long_add(1 << compound_trans_order(hpage),
>> +			atomic_long_add(1 << compound_order(hpage),
>>  					&num_poisoned_pages);
>>  		} else {
>>  			SetPageHWPoison(page);
>
>We have one more compound_trans_order() in unpoison_memory(), so could you
>replace that too?
>

See my reply to patch 3/6.

Regards,
Wanpeng Li 

>With that change ...
>Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>
>Thanks,
>Naoya Horiguchi

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