linux-kernel - Re: [PATCH v10 1/4] mm: hugetlb_vmemmap: disable hugetlb_optimize_vmemmap when struct page crosses page boundaries

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Message-ID: <f9a45337-102a-6787-4cef-3ef799490f01@redhat.com>
Date:   Thu, 12 May 2022 09:35:14 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Muchun Song <songmuchun@...edance.com>, corbet@....net,
        mike.kravetz@...cle.com, akpm@...ux-foundation.org,
        mcgrof@...nel.org, keescook@...omium.org, yzaikin@...gle.com,
        osalvador@...e.de, masahiroy@...nel.org
Cc:     linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, duanxiongchun@...edance.com, smuchun@...il.com
Subject: Re: [PATCH v10 1/4] mm: hugetlb_vmemmap: disable
 hugetlb_optimize_vmemmap when struct page crosses page boundaries

On 09.05.22 08:27, Muchun Song wrote:
> If the size of "struct page" is not the power of two but with the feature
> of minimizing overhead of struct page associated with each HugeTLB is
> enabled, then the vmemmap pages of HugeTLB will be corrupted after
> remapping (panic is about to happen in theory).  But this only exists when
> !CONFIG_MEMCG && !CONFIG_SLUB on x86_64.  However, it is not a conventional
> configuration nowadays.  So it is not a real word issue, just the result
> of a code review.
> 
> But we cannot prevent anyone from configuring that combined configure.
> This hugetlb_optimize_vmemmap should be disable in this case to fix this
> issue.
> 
> Signed-off-by: Muchun Song <songmuchun@...edance.com>
> Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>

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


-- 
Thanks,

David / dhildenb