linux-kernel - Re: [PATCH 1/4] mm/ksm: refactor out try_to_merge_with_zero

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Message-ID: <36d4f3a6-c426-4455-b5be-2ab503d380ad@linux.dev>
Date: Mon, 27 May 2024 12:36:49 +0800
From: Chengming Zhou <chengming.zhou@...ux.dev>
To: David Hildenbrand <david@...hat.com>,
 Andrew Morton <akpm@...ux-foundation.org>, aarcange@...hat.com,
 hughd@...gle.com, shr@...kernel.io
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 zhouchengming@...edance.com
Subject: Re: [PATCH 1/4] mm/ksm: refactor out try_to_merge_with_zero_page()

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@...ux.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is out of date, which means we don't need to continue, -EFAULT otherwise.