[v2,3/4] mm/migrate.c: check pagelist in move_pages_and_store_status()
diff mbox series

Message ID 20200122011647.13636-4-richardw.yang@linux.intel.com
State New
Headers show
Series
  • cleanup on do_pages_move()
Related show

Commit Message

Wei Yang Jan. 22, 2020, 1:16 a.m. UTC
When pagelist is empty, it is not necessary to do the move and store.
Also it consolidate the empty list check in one place.

Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 mm/migrate.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

Comments

David Hildenbrand Jan. 28, 2020, 10:21 a.m. UTC | #1
On 22.01.20 02:16, Wei Yang wrote:
> When pagelist is empty, it is not necessary to do the move and store.
> Also it consolidate the empty list check in one place.
> 
> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
> Acked-by: Michal Hocko <mhocko@suse.com>
> ---
>  mm/migrate.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index a4d3bd6475e1..80d2bba57265 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1499,9 +1499,6 @@ static int do_move_pages_to_node(struct mm_struct *mm,
>  {
>  	int err;
>  
> -	if (list_empty(pagelist))
> -		return 0;
> -
>  	err = migrate_pages(pagelist, alloc_new_node_page, NULL, node,
>  			MIGRATE_SYNC, MR_SYSCALL);
>  	if (err)
> @@ -1589,6 +1586,9 @@ static int move_pages_and_store_status(struct mm_struct *mm, int node,
>  {
>  	int err;
>  
> +	if (list_empty(pagelist))
> +		return 0;
> +
>  	err = do_move_pages_to_node(mm, pagelist, node);
>  	if (err)
>  		return err;
> @@ -1676,9 +1676,6 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
>  		current_node = NUMA_NO_NODE;
>  	}
>  out_flush:
> -	if (list_empty(&pagelist))
> -		return err;


Am I wrong or are you discarding an error here? (err could be !0)
Wei Yang Jan. 29, 2020, 12:46 a.m. UTC | #2
On Tue, Jan 28, 2020 at 11:21:13AM +0100, David Hildenbrand wrote:
>On 22.01.20 02:16, Wei Yang wrote:
>> When pagelist is empty, it is not necessary to do the move and store.
>> Also it consolidate the empty list check in one place.
>> 
>> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
>> Acked-by: Michal Hocko <mhocko@suse.com>
>> ---
>>  mm/migrate.c | 9 +++------
>>  1 file changed, 3 insertions(+), 6 deletions(-)
>> 
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index a4d3bd6475e1..80d2bba57265 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -1499,9 +1499,6 @@ static int do_move_pages_to_node(struct mm_struct *mm,
>>  {
>>  	int err;
>>  
>> -	if (list_empty(pagelist))
>> -		return 0;
>> -
>>  	err = migrate_pages(pagelist, alloc_new_node_page, NULL, node,
>>  			MIGRATE_SYNC, MR_SYSCALL);
>>  	if (err)
>> @@ -1589,6 +1586,9 @@ static int move_pages_and_store_status(struct mm_struct *mm, int node,
>>  {
>>  	int err;
>>  
>> +	if (list_empty(pagelist))
>> +		return 0;
>> +
>>  	err = do_move_pages_to_node(mm, pagelist, node);
>>  	if (err)
>>  		return err;
>> @@ -1676,9 +1676,6 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
>>  		current_node = NUMA_NO_NODE;
>>  	}
>>  out_flush:
>> -	if (list_empty(&pagelist))
>> -		return err;
>
>
>Am I wrong or are you discarding an error here? (err could be !0)
>

This is not obvious in this code snippet. If you look into the source code, it
might help you get the whole picture.

The following comment says:

  Make sure we do not overwrite the existing error

So we didn't eat error here.

>
>-- 
>Thanks,
>
>David / dhildenb
David Hildenbrand Jan. 29, 2020, 9:36 a.m. UTC | #3
On 29.01.20 01:46, Wei Yang wrote:
> On Tue, Jan 28, 2020 at 11:21:13AM +0100, David Hildenbrand wrote:
>> On 22.01.20 02:16, Wei Yang wrote:
>>> When pagelist is empty, it is not necessary to do the move and store.
>>> Also it consolidate the empty list check in one place.
>>>
>>> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
>>> Acked-by: Michal Hocko <mhocko@suse.com>
>>> ---
>>>  mm/migrate.c | 9 +++------
>>>  1 file changed, 3 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/mm/migrate.c b/mm/migrate.c
>>> index a4d3bd6475e1..80d2bba57265 100644
>>> --- a/mm/migrate.c
>>> +++ b/mm/migrate.c
>>> @@ -1499,9 +1499,6 @@ static int do_move_pages_to_node(struct mm_struct *mm,
>>>  {
>>>  	int err;
>>>  
>>> -	if (list_empty(pagelist))
>>> -		return 0;
>>> -
>>>  	err = migrate_pages(pagelist, alloc_new_node_page, NULL, node,
>>>  			MIGRATE_SYNC, MR_SYSCALL);
>>>  	if (err)
>>> @@ -1589,6 +1586,9 @@ static int move_pages_and_store_status(struct mm_struct *mm, int node,
>>>  {
>>>  	int err;
>>>  
>>> +	if (list_empty(pagelist))
>>> +		return 0;
>>> +
>>>  	err = do_move_pages_to_node(mm, pagelist, node);
>>>  	if (err)
>>>  		return err;
>>> @@ -1676,9 +1676,6 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
>>>  		current_node = NUMA_NO_NODE;
>>>  	}
>>>  out_flush:
>>> -	if (list_empty(&pagelist))
>>> -		return err;
>>
>>
>> Am I wrong or are you discarding an error here? (err could be !0)
>>
> 
> This is not obvious in this code snippet. If you look into the source code, it
> might help you get the whole picture.
> 
> The following comment says:
> 
>   Make sure we do not overwrite the existing error
> 
> So we didn't eat error here.

My fault, I misread the "if (err >= 0)" (and thought it was a "if (err1
>= 0)")

Makes perfect sense, thanks!

Reviewed-by: David Hildenbrand <david@redhat.com>

Patch
diff mbox series

diff --git a/mm/migrate.c b/mm/migrate.c
index a4d3bd6475e1..80d2bba57265 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1499,9 +1499,6 @@  static int do_move_pages_to_node(struct mm_struct *mm,
 {
 	int err;
 
-	if (list_empty(pagelist))
-		return 0;
-
 	err = migrate_pages(pagelist, alloc_new_node_page, NULL, node,
 			MIGRATE_SYNC, MR_SYSCALL);
 	if (err)
@@ -1589,6 +1586,9 @@  static int move_pages_and_store_status(struct mm_struct *mm, int node,
 {
 	int err;
 
+	if (list_empty(pagelist))
+		return 0;
+
 	err = do_move_pages_to_node(mm, pagelist, node);
 	if (err)
 		return err;
@@ -1676,9 +1676,6 @@  static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
 		current_node = NUMA_NO_NODE;
 	}
 out_flush:
-	if (list_empty(&pagelist))
-		return err;
-
 	/* Make sure we do not overwrite the existing error */
 	err1 = move_pages_and_store_status(mm, current_node, &pagelist,
 				status, start, i - start);