linux-kernel - Re: [PATCH v8 3/7] mm,hugetlb: Drop clearing of flag from prep_new_huge

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Message-ID: <cf4a3e6d-f69a-cf0b-dc66-b55ad06a1d1c@redhat.com>
Date:   Thu, 15 Apr 2021 14:41:41 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Michal Hocko <mhocko@...e.com>, Oscar Salvador <osalvador@...e.de>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Muchun Song <songmuchun@...edance.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 3/7] mm,hugetlb: Drop clearing of flag from
 prep_new_huge_page

On 15.04.21 13:41, Michal Hocko wrote:
> On Thu 15-04-21 12:35:40, Oscar Salvador wrote:
>> Pages allocated after boot get its private field cleared by means
>> of post_alloc_hook().
> 
> You surely meant to say s@...t@...e/cma allocator@ here

I think this also includes allocating gigantic pages via 
alloc_contig_pages() directly. post_alloc_hook() covers both.

> 
>> Pages allocated during boot, that is directly from the memblock allocator,
>> get cleared by paging_init()->..->memmap_init_zone->..->__init_single_page()
>> before any memblock allocation.
>>
>> Based on this ground, let us remove the clearing of the flag from
>> prep_new_huge_page() as it is not needed.
> 
> I would also mention that this is a leftover from 6c0371490140
> ("hugetlb: convert PageHugeFreed to HPageFreed flag"). Previously the
> explicit clearing was necessary because compound allocations do not get
> this initialization (see prep_compound_page).
> 
>> Signed-off-by: Oscar Salvador <osalvador@...e.de>
> 
> with that
> Acked-by: Michal Hocko <mhocko@...e.com>
> 

Reviewed-by: David Hildenbrand <david@...hat.com>


-- 
Thanks,

David / dhildenb