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    SubjectRe: [PATCH] netfilter: per netns nf_conntrack_cachep
    On Wed, 2010-02-03 at 21:09 +0200, Alexey Dobriyan wrote:
    > On Wed, Feb 03, 2010 at 01:38:09PM -0500, Jon Masters wrote:
    > > *). Per namespace cacheing allocation (the cachep bits). We know it's
    > > still possible for weirdness to happen in the SLAB cache here.
    > Tiny race, needs reproducer.

    Maybe. I think it's worth fixing anyway.

    > > *). Per namespace hashsize tracking. Existing code corrupts hashtables
    > > if the global size is changed when there is more than one netns
    > I think, no.
    > Changing hash size will change hashsize for all netns, current and future.

    Nope. Look at the logic in nf_conntrack_set_hashsize where you iterate
    over init_net.ct.hash but don't touch other namespaces. So then you go
    setting nf_conntrack_htable_size and will deference that in accessing
    other per-namespace hashtables using the wrong size information.

    > > *). Per namespace expectations. This is for similar reasons to the need
    > > for multiple hashtables, though I haven't poked at that.
    > Expectation cache is not SLAB_DESTROY_BY_RCU, so the logic doesn't
    > apply, I hope.

    I'm not sure, I didn't poke at that much yet. But hashtables certainly
    need fixing unless you can point out where I'm wrong.

    > > I also think it is necessary to expose net namespace layout
    > Not necessary. Why?

    How am I as a sysadmin supposed to figure out which net namespaces exist
    on my system, and as a developer, supposed to debug these situations?


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