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    SubjectRe: [PATCH] tmpfs: fix mount mpol nodelist parsing
    On Tue, 21 Feb 2006, Andrew Morton wrote:
    > Hugh Dickins <> wrote:
    > >
    > > Move the mpol= parsing to shmem_parse_mpol under CONFIG_NUMA, reject
    > > all its options as invalid if not NUMA.
    > That's a bit irritating, really. It means that userspace needs to be
    > different for NUMA kernels (or more different, which is still bad). Boot
    > into a non-NUMA kernel and whoops, no tmpfs and quite possibly no boot.

    Well spotted.

    That was a choice that gave me pause between making it and sending the
    patch. But in the end I decided we might as well. Repeating what I
    wrote to Robin about it...

    I did wonder for a while whether I'd been unhelpful to make mpol= fail
    when not CONFIG_NUMA - tiresome for someone switching between NUMA and
    non-NUMA kernels. But this is an advanced option, not something for
    everybody's /etc/fstab; and once I realized that all but the trivial
    nodelist "0" would get rejected anyway if not CONFIG_NUMA, decided it
    is best to placate the anti-bloaters with that CONFIG_NUMA after all.

    > But last time I whined about this Albert had a list of fairly
    > reasonable-sounding reasons why filesystems shouldn't silently accept
    > not-understood options.
    > But in this case, we _do_ understand them. We're just not going to do
    > anything about them.
    > I just wonder if we're being as friendly as we possibly can be to admins
    > and distro-makers.

    I doubt the distro-makers will want to be putting "mpol=" options into
    their tmpfs lines in /etc/fstab. I hope the admins of such systems
    that need it can cope.

    But perhaps I should expand the mention of CONFIG_NUMA in tmpfs.txt,
    to explain the issue, and suggest that "mpol=" be used in remounts
    rather than automatic mounts on systems where it might be a problem.
    I'll dream up some wording later.

    > [ Vaguely suprised that tmpfs isn't using match_token()... ]

    I did briefly consider that back in the days when I noticed a host of
    fs filesystems got converted. But didn't see any point in messing
    with what was already working. Haven't looked recently: would it
    actually be a useful change to make?

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      Last update: 2006-02-22 08:23    [W:0.021 / U:2.384 seconds]
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