linux-kernel - Re: [PATCH 7/7] migrate_pages(): fix failure counting for retry

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Date:   Mon, 27 Jun 2022 14:21:31 +0800
From:   "Huang, Ying" <ying.huang@...el.com>
To:     Baolin Wang <baolin.wang@...ux.alibaba.com>
Cc:     <akpm@...ux-foundation.org>, <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>, <shy828301@...il.com>, <ziy@...dia.com>
Subject: Re: [PATCH 7/7] migrate_pages(): fix failure counting for retry

Baolin Wang <baolin.wang@...ux.alibaba.com> writes:

> On 6/27/2022 10:25 AM, Huang Ying wrote:
>> After 10 retries, we will give up and the remaining pages will be
>> counted as failure in nr_failed and nr_thp_failed.  We should count
>> the failure in nr_failed_pages too.  This is done in this patch.
>> Signed-off-by: "Huang, Ying" <ying.huang@...el.com>
>> Fixes: 5984fabb6e82 ("mm: move_pages: report the number of non-attempted pages")
>> Cc: Baolin Wang <baolin.wang@...ux.alibaba.com>
>> Cc: Zi Yan <ziy@...dia.com>
>> Cc: Yang Shi <shy828301@...il.com>
>> ---
>>   mm/migrate.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index 70a0e1f34c03..e42bd409d3aa 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -1344,6 +1344,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>>   	int thp_retry = 1;
>>   	int nr_failed = 0;
>>   	int nr_failed_pages = 0;
>> +	int nr_retry_pages = 0;
>>   	int nr_succeeded = 0;
>>   	int nr_thp_succeeded = 0;
>>   	int nr_thp_failed = 0;
>> @@ -1364,6 +1365,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>>   	for (pass = 0; pass < 10 && (retry || thp_retry); pass++) {
>>   		retry = 0;
>>   		thp_retry = 0;
>> +		nr_retry_pages = 0;
>>     		list_for_each_entry_safe(page, page2, from, lru) {
>>   			/*
>> @@ -1449,12 +1451,14 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>>   				nr_thp_failed += thp_retry;
>>   				if (!no_subpage_counting)
>>   					nr_failed += retry;
>> +				nr_failed_pages += nr_retry_pages;
>
> Can you move this a little forward to update 'nr_failed_pages' in one
> place, which seems more readable?
> nr_failed_pages += nr_subpages + nr_retry_pages;

Sure.  Will do this in the next version!

> Otherwise,
> Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>

Thanks!

Best Regards,
Huang, Ying

>
>>   				goto out;
>>   			case -EAGAIN:
>>   				if (is_thp)
>>   					thp_retry++;
>>   				else
>>   					retry++;
>> +				nr_retry_pages += nr_subpages;
>>   				break;
>>   			case MIGRATEPAGE_SUCCESS:
>>   				nr_succeeded += nr_subpages;
>> @@ -1481,6 +1485,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>>   	if (!no_subpage_counting)
>>   		nr_failed += retry;
>>   	nr_thp_failed += thp_retry;
>> +	nr_failed_pages += nr_retry_pages;
>>   	/*
>>   	 * Try to migrate subpages of fail-to-migrate THPs, no nr_failed
>>   	 * counting in this round, since all subpages of a THP is counted