Received-SPF: pass (google.com: domain of linux-kernel+bounces-82645-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Message-ID: <f3b53f0e-58ce-4b2d-ba91-f347da73f9f3@kylinos.cn>
Date: Tue, 27 Feb 2024 11:14:27 +0800
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH] powerpc/mm: Code cleanup for __hash_page_thp
Content-Language: en-US
To: Michael Ellerman <mpe@ellerman.id.au>, npiggin@gmail.com,
 christophe.leroy@csgroup.eu, aneesh.kumar@kernel.org,
 naveen.n.rao@linux.ibm.com
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
References: <20240125092624.537564-1-chentao@kylinos.cn>
 <87h6hva4b0.fsf@mail.lhotse>
From: Kunwu Chan <chentao@kylinos.cn>
In-Reply-To: <87h6hva4b0.fsf@mail.lhotse>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit

Thanks for the reply.

On 2024/2/26 18:49, Michael Ellerman wrote:
> Kunwu Chan <chentao@kylinos.cn> writes:
>> This part was commented from commit 6d492ecc6489
>> ("powerpc/THP: Add code to handle HPTE faults for hugepages")
>> in about 11 years before.
>>
>> If there are no plans to enable this part code in the future,
>> we can remove this dead code.
> 
> I agree the code can go. But I'd like it to be replaced with a comment
> explaining what the dead code was trying to say.
Thanks, i'll update a new patch with the following comment:
     /*
     * No CPU has hugepages but lacks no execute, so we
     * don't need to worry about cpu no CPU_FTR_COHERENT_ICACHE feature case
     */

> 
> cheers
> 
>> diff --git a/arch/powerpc/mm/book3s64/hash_hugepage.c b/arch/powerpc/mm/book3s64/hash_hugepage.c
>> index c0fabe6c5a12..127a3a2c174b 100644
>> --- a/arch/powerpc/mm/book3s64/hash_hugepage.c
>> +++ b/arch/powerpc/mm/book3s64/hash_hugepage.c
>> @@ -59,16 +59,6 @@ int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
>>   
>>   	rflags = htab_convert_pte_flags(new_pmd, flags);
>>   
>> -#if 0
>> -	if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
>> -
>> -		/*
>> -		 * No CPU has hugepages but lacks no execute, so we
>> -		 * don't need to worry about that case
>> -		 */
>> -		rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
>> -	}
>> -#endif
>>   	/*
>>   	 * Find the slot index details for this ea, using base page size.
>>   	 */
>> -- 
>> 2.39.2
-- 
Thanks,
   Kunwu