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    SubjectRe: [PATCH] hugetlbfs: correct handling of negative input to /proc/sys/vm/nr_hugepages
    On Thu, 24 Feb 2011, Mel Gorman wrote:

    > On Wed, Feb 23, 2011 at 04:18:18PM -0800, Andrew Morton wrote:
    > > On Tue, 22 Feb 2011 10:02:36 +0000
    > > Mel Gorman <mel@csn.ul.ie> wrote:
    > >
    > > > On Mon, Feb 21, 2011 at 04:47:49PM +0100, Petr Holasek wrote:
    > > > > When user insert negative value into /proc/sys/vm/nr_hugepages it will result
    > > > > in the setting a random number of HugePages in system (can be easily showed
    > > > > at /proc/meminfo output).
    > > >
    > > > I bet you a shiny penny that the value of HugePages becomes the maximum
    > > > number that could be allocated by the system at the time rather than a
    > > > random value.
    > >
    > > That seems to be the case from my reading. In which case the patch
    > > removes probably-undocumented and possibly-useful existing behavior.
    > >
    >
    > It's not proof that no one does this but I'm not aware of any documentation
    > related to hugetlbfs that recommends writing negative values to take advantage
    > of this side-effect. It's more likely they simply wrote a very large number
    > to nr_hugepages if they wanted "as many hugepages as possible" as it makes
    > more intuitive sense than asking for a negative amount of pages. hugeadm at
    > least is not depending on this behaviour AFAIK.

    That is correct, hugeadm never writes negative values to huge page pool sizes.
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