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From: Miaohe Lin <linmiaohe@huawei.com>
To: Yin Fengwei <fengwei.yin@intel.com>
Cc: <linux-mm@kvack.org>, <naoya.horiguchi@nec.com>,
	<aaron.lu@intel.com>, <tony.luck@intel.com>,
	<qiuxu.zhuo@intel.com>, Matthew Wilcox <willy@infradead.org>
Subject: Re: [RFC PATCH] mm/memory-failure: release private data before split THP
Date: Thu, 4 Aug 2022 09:19:45 +0800	[thread overview]
Message-ID: <410bb7b3-db57-47a9-f97c-1e3441aadb23@huawei.com> (raw)
In-Reply-To: <Yupxv9+ziR+utiHX@casper.infradead.org>

On 2022/8/3 21:01, Matthew Wilcox wrote:
> On Wed, Aug 03, 2022 at 10:52:43AM +0800, Yin Fengwei wrote:
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index da39ec8afca8..08e21973b120 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -1484,7 +1484,16 @@ static int identify_page_state(unsigned long pfn, struct page *p,
>>  
>>  static int try_to_split_thp_page(struct page *page, const char *msg)
>>  {
>> +	struct page *head = compound_head(page);
>  > +
>>  	lock_page(page);
>> +	/*
>> +	 * If thp page has private data attached, thp split will fail.
>> +	 * Release private data before split thp.
>> +	 */
>> +	if (page_has_private(head))
>> +		try_to_release_page(head, GFP_KERNEL);
>> +
>>  	if (unlikely(split_huge_page(page))) {
>>  		unsigned long pfn = page_to_pfn(page);
> 
> It seems a shame to use the old page approach instead of the
> shiny new folio approach.  We're quite close to being able to remove
> try_to_release_page() in 6.1 or 6.2 so adding a new caller is a bad idea.
> How about this:
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index da39ec8afca8..765b383288b1 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1484,16 +1484,21 @@ static int identify_page_state(unsigned long pfn, struct page *p,
>  
>  static int try_to_split_thp_page(struct page *page, const char *msg)
>  {
> -	lock_page(page);
> +	struct folio *folio = page_folio(page);
> +
> +	folio_lock(folio);
> +	if (folio_test_private(folio))
> +		filemap_release_folio(folio, GFP_KERNEL);

If filemap_release_folio fails, we could avoid trying split_huge_page here?

>  	if (unlikely(split_huge_page(page))) {
>  		unsigned long pfn = page_to_pfn(page);
>  
> -		unlock_page(page);
> +		folio_unlock(folio);
>  		pr_info("%s: %#lx: thp split failed\n", msg, pfn);
> -		put_page(page);
> +		folio_put(folio);
>  		return -EBUSY;
>  	}
> -	unlock_page(page);
> +	folio = page_folio(page);

Above line (re-fetching folio) might need a comment to avoid future confusing ?

Anyway, this patch looks good to me. Thanks for fixing.

> +	folio_unlock(folio);
>  
>  	return 0;
>  }
> 
> .
> 



  parent reply	other threads:[~2022-08-04  1:19 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-03  2:52 [RFC PATCH] mm/memory-failure: release private data before split THP Yin Fengwei
2022-08-03  9:39 ` HORIGUCHI NAOYA(堀口 直也)
2022-08-03 14:42   ` Yin, Fengwei
2022-08-03 13:01 ` Matthew Wilcox
2022-08-03 13:32   ` Yin, Fengwei
2022-08-03 13:36     ` Matthew Wilcox
2022-08-03 13:40       ` Yin, Fengwei
2022-08-03 14:33       ` Yin, Fengwei
2022-08-03 15:26         ` Matthew Wilcox
2022-08-04  1:19   ` Miaohe Lin [this message]
2022-08-04  1:54     ` Yin Fengwei
2022-08-04  2:05       ` Miaohe Lin

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