Re: [PATCH] mm: compact: fix zoneindex in compact

[Chen Feng]

On 2016/5/20 1:45, Vlastimil Babka wrote:
> On 19.5.2016 19:23, Hugh Dickins wrote:
>> On Thu, 19 May 2016, Vlastimil Babka wrote:
>>> On 05/19/2016 02:11 PM, Vlastimil Babka wrote:
>>>> On 05/19/2016 01:58 PM, Chen Feng wrote:
>>>>> While testing the kcompactd in my platform 3G MEM only DMA ZONE.
>>>>> I found the kcompactd never wakeup. It seems the zoneindex
>>>>> has already minus 1 before. So the traverse here should be <=.
>>>>
>>>> Ouch, thanks!
>>>>
>>>>> Signed-off-by: Chen Feng <puck.chen@xxxxxxxxxxxxx>
>>>>
>>>> Fixes: 0f87baf4f7fb ("mm: wake kcompactd before kswapd's short sleep")
>>>
>>> Bah, not that one.
>>>
>>> Fixes: accf62422b3a ("mm, kswapd: replace kswapd compaction with waking
>>> up kcompactd")
>>>
>>>> Cc: stable@xxxxxxxxxxxxxxx
>>>> Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
>>>>
>>>>> ---
>>>>>  mm/compaction.c | 2 +-
>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/mm/compaction.c b/mm/compaction.c
>>>>> index 8fa2540..e5122d9 100644
>>>>> --- a/mm/compaction.c
>>>>> +++ b/mm/compaction.c
>>>>> @@ -1742,7 +1742,7 @@ static bool kcompactd_node_suitable(pg_data_t *pgdat)
>>>>>  	struct zone *zone;
>>>>>  	enum zone_type classzone_idx = pgdat->kcompactd_classzone_idx;
>>>>>  
>>>>> -	for (zoneid = 0; zoneid < classzone_idx; zoneid++) {
>>>>> +	for (zoneid = 0; zoneid <= classzone_idx; zoneid++) {
>>>>>  		zone = &pgdat->node_zones[zoneid];
>>>>>  
>>>>>  		if (!populated_zone(zone))
>>
>> Ignorant question: kcompactd_do_work() just below has a similar loop:
> 
> You spelled "Important" wrong.
> 
>> should that one be saying "zoneid <= cc.classzone_idx" too?
> 
> Yes. Chen, can you send updated patch (also with the ack/cc/fixes tags I added?)
> 
kcompactd_do_work()

This fix already added by Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>

I will not sent it.

> Thanks!
> 
>> Hugh
>>
> 
> 
> .
>