linux-kernel - Re: [PATCH v3 4/6] mm: Introduce a pageflag for partially mapped folios

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Message-ID: <c429f444-5f8b-4845-a9ee-3262c92109ad@gmail.com>
Date: Wed, 14 Aug 2024 11:20:40 +0100
From: Usama Arif <usamaarif642@...il.com>
To: Yu Zhao <yuzhao@...gle.com>
Cc: akpm@...ux-foundation.org, linux-mm@...ck.org, hannes@...xchg.org,
 riel@...riel.com, shakeel.butt@...ux.dev, roman.gushchin@...ux.dev,
 david@...hat.com, baohua@...nel.org, ryan.roberts@....com, rppt@...nel.org,
 willy@...radead.org, cerasuolodomenico@...il.com, corbet@....net,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, kernel-team@...a.com
Subject: Re: [PATCH v3 4/6] mm: Introduce a pageflag for partially mapped
 folios



On 14/08/2024 04:30, Yu Zhao wrote:
>> @@ -3558,7 +3564,6 @@ static unsigned long deferred_split_scan(struct shrinker *shrink,
>>  next:
>>                 folio_put(folio);
>>         }
>> -
> 
> Unintentional change above?

Yes, unintended new line, will fix it.
> 
>>         spin_lock_irqsave(&ds_queue->split_queue_lock, flags);
>>         list_splice_tail(&list, &ds_queue->split_queue);
>>         spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>> index 1fdd9eab240c..2ae2d9a18e40 100644
>> --- a/mm/hugetlb.c
>> +++ b/mm/hugetlb.c
>> @@ -1758,6 +1758,7 @@ static void __update_and_free_hugetlb_folio(struct hstate *h,
>>                 free_gigantic_folio(folio, huge_page_order(h));
>>         } else {
>>                 INIT_LIST_HEAD(&folio->_deferred_list);
>> +               folio_clear_partially_mapped(folio);
> 
> Why does it need to clear a flag that should never be set on hugeTLB folios?
> 
> HugeTLB does really use _deferred_list -- it clears it only to avoid
> bad_page() because of the overlapping fields:
>                         void *_hugetlb_subpool;
>                         void *_hugetlb_cgroup;

Yes, thats right, will remove it. Thanks!