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Date:   Tue, 17 May 2022 09:34:52 +0200
From:   Oscar Salvador <osalvador@suse.de>
To:     Muchun Song <songmuchun@bytedance.com>
Cc:     corbet@lwn.net, mike.kravetz@oracle.com, akpm@linux-foundation.org,
        mcgrof@kernel.org, keescook@chromium.org, yzaikin@google.com,
        david@redhat.com, masahiroy@kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        duanxiongchun@bytedance.com, smuchun@gmail.com
Subject: Re: [PATCH v12 1/7] mm: hugetlb_vmemmap: disable
 hugetlb_optimize_vmemmap when struct page crosses page boundaries
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 <20220516102211.41557-2-songmuchun@bytedance.com>
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On Mon, May 16, 2022 at 06:22:05PM +0800, 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@bytedance.com>
> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
> Acked-by: David Hildenbrand <david@redhat.com>

Reviewed-by: Oscar Salvador <osalvador@suse.de>

-- 
Oscar Salvador
SUSE Labs