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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
        David Hildenbrand <david@redhat.com>
Cc:     linux-mm@kvack.org, linux-arch@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH 10/10] mm, treewide: Redefine MAX_ORDER sanely
In-Reply-To: <20230315113133.11326-11-kirill.shutemov@linux.intel.com>
References: <20230315113133.11326-1-kirill.shutemov@linux.intel.com>
 <20230315113133.11326-11-kirill.shutemov@linux.intel.com>
Date:   Wed, 22 Mar 2023 14:26:59 +1100
Message-ID: <871qlhv530.fsf@mpe.ellerman.id.au>
MIME-Version: 1.0
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"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> writes:
> MAX_ORDER currently defined as number of orders page allocator supports:
> user can ask buddy allocator for page order between 0 and MAX_ORDER-1.
>
> This definition is counter-intuitive and lead to number of bugs all over
> the kernel.
>
> Change the definition of MAX_ORDER to be inclusive: the range of orders
> user can ask from buddy allocator is 0..MAX_ORDER now.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> ---
...
>  arch/powerpc/Kconfig                          | 27 ++++++-------
>  arch/powerpc/configs/85xx/ge_imp3a_defconfig  |  2 +-
>  arch/powerpc/configs/fsl-emb-nonhw.config     |  2 +-
>  arch/powerpc/mm/book3s64/iommu_api.c          |  2 +-
>  arch/powerpc/mm/hugetlbpage.c                 |  2 +-
>  arch/powerpc/platforms/powernv/pci-ioda.c     |  2 +-

Reviewed-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)

cheers