Messages in this thread | | | Date | Wed, 22 Feb 2006 07:21:41 +0000 (GMT) | From | Hugh Dickins <> | Subject | Re: [PATCH] tmpfs: fix mount mpol nodelist parsing |
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On Tue, 21 Feb 2006, Andrew Morton wrote: > Hugh Dickins <hugh@veritas.com> 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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