linux-kernel - Re: [PATCH] mm/hugetlb: two-phase hugepage allocation when reservation is high

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Message-ID: <b276a150-92f3-408c-b146-7408b68ec778@redhat.com>
Date: Wed, 27 Aug 2025 14:37:33 +0200
From: David Hildenbrand <david@...hat.com>
To: "Li,Rongqing" <lirongqing@...du.com>,
 "muchun.song@...ux.dev" <muchun.song@...ux.dev>,
 "osalvador@...e.de" <osalvador@...e.de>,
 "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
 "linux-mm@...ck.org" <linux-mm@...ck.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "giorgitchankvetadze1997@...il.com" <giorgitchankvetadze1997@...il.com>
Cc: "Xu,Wenjie(ACG CCN)" <xuwenjie04@...du.com>
Subject: Re: [PATCH] mm/hugetlb: two-phase hugepage allocation when
 reservation is high

On 27.08.25 14:33, Li,Rongqing wrote:
>> Not sure if something like the following could fly:
>>
>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c index
>> 1f42186a85ea4..dfb4d717b8a02 100644
>> --- a/mm/hugetlb.c
>> +++ b/mm/hugetlb.c
>> @@ -3595,8 +3595,6 @@ static unsigned long __init
>> hugetlb_pages_alloc_boot(struct hstate *h)
>>           unsigned long jiffies_end;
>>
>>           job.thread_fn   = hugetlb_pages_alloc_boot_node;
>> -       job.start       = 0;
>> -       job.size        = h->max_huge_pages;
>>
>>           /*
>>            * job.max_threads is 25% of the available cpu threads by default.
>> @@ -3620,10 +3618,24 @@ static unsigned long __init
>> hugetlb_pages_alloc_boot(struct hstate *h)
>>           }
>>
>>           job.max_threads = hugepage_allocation_threads;
>> -       job.min_chunk   = h->max_huge_pages /
>> hugepage_allocation_threads;
>>
>>           jiffies_start = jiffies;
>> -       padata_do_multithreaded(&job);
>> +       /* TODO: comment why we retry and how it interacts with
>> vmemmap op. */
>> +       while (h->nr_huge_pages != h->max_huge_pages) {
>> +               unsigned long remaining = h->max_huge_pages -
>> + h->nr_huge_pages;
>> +
>> +               job.start       = h->nr_huge_pages;
>> +               job.size        = remaining;
>> +               job.min_chunk   = remaining /
>> hugepage_allocation_threads;
>> +               padata_do_multithreaded(&job);
>> +
>> +               if (hugetlb_vmemmap_optimizable(h))
>> +                       break;
> 
> It should be:
>             if (!hugetlb_vmemmap_optimizable(h))
>                       break;

Very right.

-- 
Cheers

David / dhildenb