linux-kernel - Re: [PATCH v4] mm: shrink skip folio mapped by an exiting task

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Message-ID: <016ce193-9b19-4621-817b-782fd3dd6449@vivo.com>
Date: Mon, 8 Jul 2024 17:25:57 +0800
From: zhiguojiang <justinjiang@...o.com>
To: Matthew Wilcox <willy@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, Barry Song <baohua@...nel.org>,
 opensource.kernel@...o.com,
 Qianfeng Rong <rongqianfeng@...o.corp-partner.google.com>
Subject: Re: [PATCH v4] mm: shrink skip folio mapped by an exiting task



在 2024/7/8 11:34, Matthew Wilcox 写道:
> On Mon, Jul 08, 2024 at 11:15:17AM +0800, Zhiguo Jiang wrote:
>> If an anon folio reclaimed by shrink_inactive_list is mapped by an
>> exiting task, this anon folio will be firstly swaped-out into
>> swapspace in shrink flow and then this swap folio is freed in task
>> exit flow. But if this folio mapped by an exiting task can skip
>> shrink and be freed directly in task exiting flow, which will save
>> swap-out time and alleviate the load of the tasks exiting process.
>> The file folio is also similar.
> How is the file folio similar?  File folios are never written to swap,
> and they'll be written back from the page cache whenever the filesystem
> decides it's a good time to do so.
>
>>   mm/rmap.c | 10 ++++++++++
>>   1 file changed, 10 insertions(+)
>>   mode change 100644 => 100755 mm/rmap.c
> Uh, what?  Why would you make this file executable?
>
>> diff --git a/mm/rmap.c b/mm/rmap.c
>> index 26806b49a86f..16b7ed04bcbe
>> --- a/mm/rmap.c
>> +++ b/mm/rmap.c
>> @@ -843,6 +843,16 @@ static bool folio_referenced_one(struct folio *folio,
>>   	int referenced = 0;
>>   	unsigned long start = address, ptes = 0;
>>   
>> +	/* Skip the unshared folios mapped only by the single
>> +	 * exiting process.
>> +	 */
> Comments start with a /* on a line by itself.
>
>> +	if ((!atomic_read(&vma->vm_mm->mm_users) ||
>> +		test_bit(MMF_OOM_SKIP, &vma->vm_mm->flags)) &&
>> +		!test_bit(VM_SHARED, &vma->vm_flags)) {
>> +		pra->referenced = -1;
>> +		return false;
> This indentation is unreadable.  Follow the style used in the rest of
> the file.
Update in patch v5.
https://lore.kernel.org/linux-mm/20240708090413.888-1-justinjiang@vivo.com/
Thanks
>