linux-kernel - Re: [PATCH] mm: compact: fix zoneindex in compact

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Date:	Fri, 20 May 2016 09:00:04 +0800
From:	Chen Feng <puck.chen@...ilicon.com>
To:	Vlastimil Babka <vbabka@...e.cz>, Hugh Dickins <hughd@...gle.com>
CC:	<mhocko@...e.com>, <kirill.shutemov@...ux.intel.com>,
	<hannes@...xchg.org>, <tj@...nel.org>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	<suzhuangluan@...ilicon.com>, <dan.zhao@...ilicon.com>,
	<qijiwen@...ilicon.com>, <xuyiping@...ilicon.com>,
	<oliver.fu@...ilicon.com>, <puck.chen@...mail.com>
Subject: Re: [PATCH] mm: compact: fix zoneindex in compact



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@...ilicon.com>
>>>>
>>>> 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@...r.kernel.org
>>>> Acked-by: Vlastimil Babka <vbabka@...e.cz>
>>>>
>>>>> ---
>>>>>  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:
> 

Yes, my mistake.
> 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?)
> 
OK, I will send it out soon.

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