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Message-ID: <f839ae47-2776-4684-a331-564554426ae2@linux.dev>
Date: Mon, 27 May 2024 15:41:21 +0800
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Subject: Re: [PATCH 1/4] mm/ksm: refactor out try_to_merge_with_zero_page()
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To: David Hildenbrand <david@redhat.com>,
 Andrew Morton <akpm@linux-foundation.org>, aarcange@redhat.com,
 hughd@google.com, shr@devkernel.io
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
 zhouchengming@bytedance.com
References: <20240524-b4-ksm-scan-optimize-v1-0-053b31bd7ab4@linux.dev>
 <20240524-b4-ksm-scan-optimize-v1-1-053b31bd7ab4@linux.dev>
 <18259f7c-d57e-4504-91ec-90b7c87aad01@redhat.com>
 <36d4f3a6-c426-4455-b5be-2ab503d380ad@linux.dev>
 <18ad1a9f-8f00-41c1-9c77-ac3252061852@redhat.com>
From: Chengming Zhou <chengming.zhou@linux.dev>
In-Reply-To: <18ad1a9f-8f00-41c1-9c77-ac3252061852@redhat.com>
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On 2024/5/27 15:18, David Hildenbrand wrote:
> Am 27.05.24 um 06:36 schrieb Chengming Zhou:
>> On 2024/5/24 23:12, David Hildenbrand wrote:
>>> On 24.05.24 10:56, Chengming Zhou wrote:
>>>> In preparation for later changes, refactor out a new function called
>>>> try_to_merge_with_zero_page(), which tries to merge with zero page.
>>>>
>>>> Signed-off-by: Chengming Zhou <chengming.zhou@linux.dev>
>>>> ---
>>>>    mm/ksm.c | 67 +++++++++++++++++++++++++++++++++++-----------------------------
>>>>    1 file changed, 37 insertions(+), 30 deletions(-)
>>>>
>>>> diff --git a/mm/ksm.c b/mm/ksm.c
>>>> index 4dc707d175fa..cbd4ba7ea974 100644
>>>> --- a/mm/ksm.c
>>>> +++ b/mm/ksm.c
>>>> @@ -1531,6 +1531,41 @@ static int try_to_merge_one_page(struct vm_area_struct *vma,
>>>>        return err;
>>>>    }
>>>>    +/* This function returns 0 if the pages were merged, -EFAULT otherwise. */
>>>
>>> No it doesn't. Check the "err = 0" case.
>>>
>>
>> Right, how about this: This function returns 0 if the page were merged or the vma
>> is out of date, which means we don't need to continue, -EFAULT otherwise.
> 
> Maybe slightly adjusted:
> 
> This function returns 0 if the pages were merged or if they are no longer merging candidates (e.g., VMA stale), -EFAULT otherwise.
> 

Great, will change to this. Thanks!