linux-kernel - Re: [PATCH v8 1/6] ksm: support unsharing KSM-placed zero pages

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Message-ID: <4b7e4d48-f0f9-c0b0-e8e1-2678d0306252@redhat.com>
Date:   Tue, 23 May 2023 16:00:39 +0200
From:   David Hildenbrand <david@...hat.com>
To:     xu xin <xu.xin.sc@...il.com>
Cc:     akpm@...ux-foundation.org, imbrenda@...ux.ibm.com,
        jiang.xuexin@....com.cn, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, ran.xiaokai@....com.cn, xu.xin16@....com.cn,
        yang.yang29@....com.cn
Subject: Re: [PATCH v8 1/6] ksm: support unsharing KSM-placed zero pages

On 23.05.23 15:57, xu xin wrote:
>>> ---
>>>    include/linux/ksm.h | 6 ++++++
>>>    mm/ksm.c            | 5 +++--
>>>    2 files changed, 9 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/include/linux/ksm.h b/include/linux/ksm.h
>>> index 899a314bc487..7989200cdbb7 100644
>>> --- a/include/linux/ksm.h
>>> +++ b/include/linux/ksm.h
>>> @@ -26,6 +26,9 @@ int ksm_disable(struct mm_struct *mm);
>>>    
>>>    int __ksm_enter(struct mm_struct *mm);
>>>    void __ksm_exit(struct mm_struct *mm);
>>> +/* use pte_mkdirty to track a KSM-placed zero page */
>>> +#define set_pte_ksm_zero(pte)	pte_mkdirty(pte_mkspecial(pte))
>>
>> If there is only a single user (which I assume), please inline it instead.
> 
> Excuse me, I'm wondering why using inline here instead of macro is better.
> Thanks! :)

Just to clarify: not an inline function but removing the macro 
completely and just place that code directly into the single caller.

Single user, no need to put that into ksm.h -- and I'm not super happy 
about the set_pte_ksm_zero() name ;) because we get the zero-pte already 
passed in from the caller ...

-- 
Thanks,

David / dhildenb