2022-07-12 02:29:07

by Miaohe Lin

Subject: Re: [PATCH] mm/compaction: fix set skip in fast_find_migrateblock

Add Cc Andrew and linux-kernel email list.

On 2022/7/11 20:32, Zhou Chuyi wrote:
> From: zhouchuyi <[email protected]>
>
> 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 <[email protected]>

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!

> break;
> }
> }
>

2022-07-12 09:05:48

by Chuyi Zhou

Subject: Re: [External] Re: [PATCH] mm/compaction: fix set skip in fast_find_migrateblock

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 <[email protected]>
>>
>> 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 <[email protected]>
>
> 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;
>> }
>> }
>>
>