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Date: Fri, 24 Oct 2025 16:54:44 +0200
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Subject: Re: [PATCH v3 03/13] powerpc/mm: implement arch_flush_lazy_mmu_mode()
To: David Hildenbrand <david@redhat.com>, linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org, Alexander Gordeev <agordeev@linux.ibm.com>,
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References: <20251015082727.2395128-1-kevin.brodsky@arm.com>
 <20251015082727.2395128-4-kevin.brodsky@arm.com>
 <60c55686-87dd-46d0-884e-80f7d423663b@redhat.com>
 <604f26cb-46c6-4533-8110-0b174eed821d@arm.com>
 <5d5a85ec-0213-4af3-92a9-c02bb13da073@redhat.com>
Content-Language: en-GB
From: Kevin Brodsky <kevin.brodsky@arm.com>
In-Reply-To: <5d5a85ec-0213-4af3-92a9-c02bb13da073@redhat.com>
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On 24/10/2025 16:42, David Hildenbrand wrote:
> On 24.10.25 14:09, Kevin Brodsky wrote:
>> On 23/10/2025 21:36, David Hildenbrand wrote:
>>> On 15.10.25 10:27, Kevin Brodsky wrote:
>>>> [...]
>>>>
>>>> diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush-hash.h
>>>> b/arch/powerpc/include/asm/book3s/64/tlbflush-hash.h
>>>> index 146287d9580f..7704dbe8e88d 100644
>>>> --- a/arch/powerpc/include/asm/book3s/64/tlbflush-hash.h
>>>> +++ b/arch/powerpc/include/asm/book3s/64/tlbflush-hash.h
>>>> @@ -41,6 +41,16 @@ static inline void arch_enter_lazy_mmu_mode(void)
>>>>        batch->active = 1;
>>>>    }
>>>>    +static inline void arch_flush_lazy_mmu_mode(void)
>>>> +{
>>>> +    struct ppc64_tlb_batch *batch;
>>>> +
>>>> +    batch = this_cpu_ptr(&ppc64_tlb_batch);
>>>
>>> The downside is the double this_cpu_ptr() now on the
>>> arch_leave_lazy_mmu_mode() path.
>>
>> This is only temporary, patch 9 removes it from arch_enter(). I don't
>> think having a redundant this_cpu_ptr() for a few commits is really a
>> concern?
>
> Oh, right. Consider mentioning in the patch description
>
> "Note that follow-up patches will remove the double this_cpu_ptr() on
> the arch_leave_lazy_mmu_mode() path again." 

Sounds good, will do.

- Kevin