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Date:   Tue, 17 Oct 2023 12:46:36 +0200
From:   Pavel Machek <pavel@ucw.cz>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     Mikulas Patocka <mpatocka@redhat.com>,
        "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>, quic_jhugo@quicinc.com,
        snitzer@kernel.org, dm <dm-devel@redhat.com>, linux-mm@kvack.org,
        linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 00/10] Fix confusion around MAX_ORDER
Message-ID: <ZS5mDNCRkp/RGm45@duo.ucw.cz>
References: <20230315113133.11326-1-kirill.shutemov@linux.intel.com>
 <3c25ec6f-cd33-9445-a76f-6ec2c30755f5@redhat.com>
 <86e7f97a-ac6b-873d-93b2-1121a464989a@redhat.com>
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On Thu 2023-09-28 18:57:18, Paolo Bonzini wrote:
> On 9/28/23 09:50, Mikulas Patocka wrote:
> > > > Fix the bugs and then change the definition of MAX_ORDER to be
> > > > inclusive: the range of orders user can ask from buddy allocator is
> > > > 0..MAX_ORDER now.
> > I think that exclusive MAX_ORDER is more intuitive in the C language -
> > i.e. if you write "for (i =3D 0; i < MAX_ORDER; i++)", you are supposed=
 to
> > loop over all allowed values. If you declare an array "void
> > *array[MAX_ORDER];" you are supposed to hold a value for each allowed
> > order.
> >=20
> > Pascal has for loops and array dimensions with inclusive ranges - and it
> > is more prone to off-by-one errors.
>=20
> I agree it's somewhat confusing either way but the ship has sailed, the
> patch has been included in Linux for several months.

Just make sure people don't backport it to stable. Fixes: (the commit
that causes the semantic change) should do the trick.

BR,
								Pavel
--=20
People of Russia, stop Putin before his war on Ukraine escalates.

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