Message-ID: <4ed1ebe6-0579-1f1b-6dae-7fd04f40b3d1@linux.alibaba.com>
Date:   Wed, 15 Mar 2023 09:27:42 +0800
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Subject: Re: [PATCH 2/2] mm: compaction: fix the possible deadlock when
 isolating hugetlb pages
To:     Mike Kravetz <mike.kravetz@oracle.com>
Cc:     akpm@linux-foundation.org, mgorman@techsingularity.net,
        osalvador@suse.de, vbabka@suse.cz, william.lam@bytedance.com,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
References: <1bc1c955b03603c4e14f56dfbbef9f637f18dbbd.1678703534.git.baolin.wang@linux.alibaba.com>
 <a24a86fbae09711e61dc4424aa7aebff718e9995.1678703534.git.baolin.wang@linux.alibaba.com>
 <20230313170838.GA3044@monkey>
 <db50d82c-07f1-6a87-6960-7810c54f8093@linux.alibaba.com>
 <20230314172725.GA4769@monkey>
From:   Baolin Wang <baolin.wang@linux.alibaba.com>
In-Reply-To: <20230314172725.GA4769@monkey>
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On 3/15/2023 1:27 AM, Mike Kravetz wrote:
> On 03/14/23 12:11, Baolin Wang wrote:
>> On 3/14/2023 1:08 AM, Mike Kravetz wrote:
>>> On 03/13/23 18:37, Baolin Wang wrote:
>>>
>>> It would seem that the pfn of a hugetlb page would always be a multiple of
>>> COMPACT_CLUSTER_MAX so we would drop the lock.  However, I am not sure if
>>> that is ALWAYS true and would prefer something like the code you suggested.
>>
>> Well, this is not always true, suppose the CONT-PTE hugetlb on ARM arch,
>> which contains 16 contiguous normal pages.
>>
> 
> Right.  I keep forgetting about the CONT-* page sizes on arm :(
> 
> In any case, I think explicitly dropping the lock as you have done is a
> good idea.
> 
> Feel free to add,
> 
> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>

Thanks for reviewing.