Re: [PATCH RFC] ipoib: good references make good neighbors

[Chris Mason <chris.mason-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

On Mon, Aug 30, 2010 at 05:11:01PM -0700, Ralph Campbell wrote:

[ add a reference to neighbours inside ipoib ]

> The problem with this solution is that it creates
> a reference counting "loop" so that the reference
> count never goes to zero.
> struct neighbour in the kernel points to struct ipoib_neigh
> which points back to struct neighbor. If the "back pointer"
> holds a reference, then something besides ipoib_neigh_free()
> has to do the neigh_release(neighbour).
> 
> I think the real fix is the patch I sent to linux-rdma:
> https://patchwork.kernel.org/patch/120013/

patchwork is keeping this one secret for now:

OperationalError at /patch/120013/

(1040, 'Too many connections')

But I'll check back later today.  We'd hit this corruption at least once
a day under load, and we couldn't reboot a rack of machines without half
of them exploding as others went down (without CONFIG_PAGE_DEBUG_ALLOC)

So I'm a bit relieved that someone else has seen it too ;)

-chris
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