Received-SPF: pass (google.com: domain of linux-kernel+bounces-178450-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
From: ran xiaokai <ranxiaokai627@163.com>
To: david@redhat.com
Cc: ran.xiaokai@zte.com.cn,
	akpm@linux-foundation.org,
	linux-kernel@vger.kernel.org,
	linux-mm@kvack.org,
	shy828301@gmail.com,
	willy@infradead.org,
	xu.xin16@zte.com.cn,
	ziy@nvidia.com
Subject: Re: [PATCH linux-next] mm/huge_memory: mark racy access on huge_anon_orders_always
Date: Tue, 14 May 2024 08:44:03 +0000
Message-Id: <20240514084403.661740-1-ranxiaokai627@163.com>
In-Reply-To: <10529556-e22d-4afa-803d-c75511ce8425@redhat.com>
References: <10529556-e22d-4afa-803d-c75511ce8425@redhat.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

Hi, David

Thanks for taking time to review!

>> From: Ran Xiaokai <ran.xiaokai@zte.com.cn>
>> 
>> huge_anon_orders_always and huge_anon_orders_always are accessed
>
> "huge_anon_orders_always" mentioned twice.

yes, my mistake.

>> lockless, it is better to use the READ_ONCE() wrapper.
>> This is not fixing any visible bug, hopefully this can cease some
>> KCSAN complains in the future.
>> Also do that for huge_anon_orders_madvise.
>> 
>> Signed-off-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
>> ---
>>   include/linux/huge_mm.h | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>> 
>> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
>> index de0c89105076..6573430ea600 100644
>> --- a/include/linux/huge_mm.h
>> +++ b/include/linux/huge_mm.h
>> @@ -122,8 +122,8 @@ static inline bool hugepage_flags_enabled(void)
>>   	 * So we don't need to look at huge_anon_orders_inherit.
>>   	 */
>>   	return hugepage_global_enabled() ||
>> -	       huge_anon_orders_always ||
>> -	       huge_anon_orders_madvise;
>> +			READ_ONCE(huge_anon_orders_always) ||
>> +			READ_ONCE(huge_anon_orders_madvise);
>
> Don't mess up the alignment please.

yes.

I will wait for other feedbacks and then send out a v2 version.

>>   }
>> 
>>   static inline int highest_order(unsigned long orders)
>
> Acked-by: David Hildenbrand <david@redhat.com>