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Message-ID: <d855de6c-766e-cf77-feeb-a0130052ddd4@bytedance.com>
Date:   Tue, 12 Jul 2022 16:44:53 +0800
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Subject: Re: [External] Re: [PATCH] mm/compaction: fix set skip in
 fast_find_migrateblock
To:     Miaohe Lin <linmiaohe@huawei.com>, linux-mm@kvack.org
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
References: <20220711123213.66068-1-zhouchuyi@bytedance.com>
 <8af11329-93d4-3bbd-fe4c-343663c00a1b@huawei.com>
From:   =?UTF-8?B?5ZGo5L+25piT?= <zhouchuyi@bytedance.com>
In-Reply-To: <8af11329-93d4-3bbd-fe4c-343663c00a1b@huawei.com>
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在 2022/7/12 上午10:26, Miaohe Lin 写道:
> Add Cc Andrew and linux-kernel email list.
> 
> On 2022/7/11 20:32, Zhou Chuyi wrote:
>> From: zhouchuyi <zhouchuyi@bytedance.com>
>>
>> When we successfully find a pageblock in fast_find_migrateblock(), the block will be set skip-flag through set_pageblock_skip(). However, when entering isolate_migratepages_block(), the whole pageblock will be skipped due to the branch 'if (!valid_page && IS_ALIGNED(low_pfn, pageblock_nr_pages))'. Eventually we will goto isolate_abort and isolate nothing.
>> Signed-off-by: zhouchuyi <zhouchuyi@bytedance.com>
> 
> It seems we should tweak the commit log to satisfy the checkpatch.pl first.
> 
>> ---
>>   mm/compaction.c | 1 -
>>   1 file changed, 1 deletion(-)
>>
>> diff --git a/mm/compaction.c b/mm/compaction.c
>> index 1f89b969c..a1a2b50c8 100644
>> --- a/mm/compaction.c
>> +++ b/mm/compaction.c
>> @@ -1852,7 +1852,6 @@ static unsigned long fast_find_migrateblock(struct compact_control *cc)
>>   					pfn = cc->zone->zone_start_pfn;
>>   				cc->fast_search_fail = 0;
>>   				found_block = true;
>> -				set_pageblock_skip(freepage);
> 
> This looks like a real problem. Should we add a Fixes tag here? What's the runtime effect of it?
> 
> Thanks for your patch!
sorry for this mistakes, I'm a beginner of Linux kernel. I will fix this 
problems in v2
> 
>>   				break;
>>   			}
>>   		}
>>
>