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Message-ID: <0f8d2f71-c77b-4804-b762-cc40f23f88cd@vivo.com>
Date: Fri, 2 Feb 2024 17:36:34 +0800
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v2] mm:vmscan: shrink skip folio mapped by an exiting task
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
 opensource.kernel@vivo.com, Matthew Wilcox <willy@infradead.org>
References: <20240131131244.1144-1-justinjiang@vivo.com>
 <20240202012251.1aa5afbfdf2f8b3a862bced3@linux-foundation.org>
From: zhiguojiang <justinjiang@vivo.com>
In-Reply-To: <20240202012251.1aa5afbfdf2f8b3a862bced3@linux-foundation.org>
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在 2024/2/2 17:22, Andrew Morton 写道:
> On Wed, 31 Jan 2024 21:12:44 +0800 Zhiguo Jiang <justinjiang@vivo.com> wrote:
>
>> --- a/mm/rmap.c
>> +++ b/mm/rmap.c
>> @@ -840,6 +840,13 @@ static bool folio_referenced_one(struct folio *folio,
>>   	int referenced = 0;
>>   	unsigned long start = address, ptes = 0;
>>   
>> +	/* Skip this folio if it's mapped by an exiting task */
>> +	if (unlikely(!atomic_read(&vma->vm_mm->mm_users)) ||
>> +		unlikely(test_bit(MMF_OOM_SKIP, &vma->vm_mm->flags))) {
>> +		pra->referenced = -1;
>> +		return false;
>> +	}
> The code comment explains what the code does.  This is, as usual,
> pretty obvious from reading the code!
>
> A better comment is one which explains *why* the code is doing what it
> does.
Yes, thank you for your recognition, and I also appreciate Matthew Wilcox's
professional and patient guidance in patch v1. I will study this 
seriously in the
future.

Best Regards.