linux-kernel - Re: [PATCH] mm: fix misuse of update_mmu_cache() in do_anonymous

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Message-ID: <1a69af58-b9d2-6319-9db7-f92428b87612@redhat.com>
Date:   Mon, 26 Sep 2022 10:42:23 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Qi Zheng <zhengqi.arch@...edance.com>,
        Muchun Song <muchun.song@...ux.dev>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linux MM <linux-mm@...ck.org>, linux-kernel@...r.kernel.org,
        chris@...kel.net, jcmvbkbc@...il.com, maobibo@...ngson.cn
Subject: Re: [PATCH] mm: fix misuse of update_mmu_cache() in
 do_anonymous_page()

On 26.09.22 10:41, Qi Zheng wrote:
> 
> 
> On 2022/9/26 16:32, David Hildenbrand wrote:
>> On 25.09.22 03:43, Muchun Song wrote:
>>>
>>>
>>>> On Sep 24, 2022, at 13:32, Qi Zheng <zhengqi.arch@...edance.com> wrote:
>>>>
>>>> As message in commit 7df676974359 ("mm/memory.c: Update local TLB
>>>> if PTE entry exists") said, we should update local TLB only on the
>>>> second thread. So fix the misuse of update_mmu_cache() by using
>>>> update_mmu_tlb() in the do_anonymous_page().
>>>>
>>>> Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
>>>
>>> The change looks good to me. However, I am not sure what is the
>>> user-visible
>>> effect to xtensa users. So Cc xtensa’s maintainer and the author of
>>> 7df676974359
>>> to double check this.
>>
>> And if there is one, do we have a fixes tag?
> 
> IIUC, there's only a performance difference here, so maybe there's no
> need to add the fixes tag?

Maybe be careful with the usage of "fix" in subject/description then and 
point that out in the description :)

-- 
Thanks,

David / dhildenb