linux-kernel - Re: [PATCH v4 2/2] HWPOISON: soft offlining for non-lru movable page

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Date:   Mon, 30 Jan 2017 23:04:13 +0800
From:   Yisheng Xie <ysxie@...mail.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        n-horiguchi@...jp.nec.com, akpm@...ux-foundation.org,
        minchan@...nel.org, vbabka@...e.cz, guohanjun@...wei.com,
        qiuxishi@...wei.com
Subject: Re: [PATCH v4 2/2] HWPOISON: soft offlining for non-lru movable page

Hi, Michal,
Sorry for late reply.

On 01/26/2017 05:27 PM, Michal Hocko wrote:
> On Wed 25-01-17 23:05:38, ysxie@...mail.com wrote:
>> From: Yisheng Xie <xieyisheng1@...wei.com>
>>
>> This patch is to extends soft offlining framework to support
>> non-lru page, which already support migration after
>> commit bda807d44454 ("mm: migrate: support non-lru movable page
>> migration")
>>
>> When memory corrected errors occur on a non-lru movable page,
>> we can choose to stop using it by migrating data onto another
>> page and disable the original (maybe half-broken) one.
>>
>> Signed-off-by: Yisheng Xie <xieyisheng1@...wei.com>
>> Suggested-by: Michal Hocko <mhocko@...nel.org>
>> Suggested-by: Minchan Kim <minchan@...nel.org>
>> Reviewed-by: Minchan Kim <minchan@...nel.org>
>> Acked-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
>> CC: Vlastimil Babka <vbabka@...e.cz>
>> ---
>>  mm/memory-failure.c | 26 ++++++++++++++++----------
>>  1 file changed, 16 insertions(+), 10 deletions(-)
>>
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index f283c7e..56e39f8 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -1527,7 +1527,8 @@ static int get_any_page(struct page *page, unsigned long pfn, int flags)
>>  {
>>  	int ret = __get_any_page(page, pfn, flags);
>>  
>> -	if (ret == 1 && !PageHuge(page) && !PageLRU(page)) {
>> +	if (ret == 1 && !PageHuge(page) &&
>> +	    !PageLRU(page) && !__PageMovable(page)) {
>>  		/*
>>  		 * Try to free it.
>>  		 */
> Is this sufficient? Not that I am familiar with get_any_page() but
> __get_any_page doesn't seem to be aware of movable pages and neither
> shake_page is.
Sorry,maybe I do not quite get what you mean.
 If the page can be migrated, it can skip "shake_page and __get_any_page once more" here,
though it is not a free page. right ?
Please let me know if I miss anything.

>> @@ -1649,7 +1650,10 @@ static int __soft_offline_page(struct page *page, int flags)
>>  	 * Try to migrate to a new page instead. migrate.c
>>  	 * handles a large number of cases for us.
>>  	 */
>> -	ret = isolate_lru_page(page);
>> +	if (PageLRU(page))
>> +		ret = isolate_lru_page(page);
>> +	else if (!isolate_movable_page(page, ISOLATE_UNEVICTABLE))
>> +		ret = -EBUSY;
> As pointed out in the previous response isolate_movable_page should
> really have the same return value contract as [__]isolate_lru_page
Yes, I agree with your suggestion. I will rewrite it in later patch if it is suitable.
as I mention before.

Thanks again for your reviewing.

Yisheng Xie
>>  	/*
>>  	 * Drop page reference which is came from get_any_page()
>>  	 * successful isolate_lru_page() already took another one.