linux-kernel - Re: [PATCH 2/2] mm: compaction: fix the possible deadlock when isolating hugetlb pages

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Date:   Wed, 15 Mar 2023 09:27:42 +0800
From:   Baolin Wang <baolin.wang@...ux.alibaba.com>
To:     Mike Kravetz <mike.kravetz@...cle.com>
Cc:     akpm@...ux-foundation.org, mgorman@...hsingularity.net,
        osalvador@...e.de, vbabka@...e.cz, william.lam@...edance.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] mm: compaction: fix the possible deadlock when
 isolating hugetlb pages



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@...cle.com>

Thanks for reviewing.