Re: rtnl_mutex deadlock?

On Wed, Aug 05, 2015 at 08:59:07PM +0200, Daniel Borkmann wrote:

Here's a theory and patch below. Herbert, Thomas, does this make any
sense to you resp. sound plausible? ;)

It's certainly possible.  Whether it's plausible I'm not so sure.
The netlink hashtable is unlimited in size.  So it should always
be expanding, not rehashing.  The bug you found should only affect
rehashing.

I'm not quite sure what's best to return from here, i.e. whether we
propagate -ENOMEM or instead retry over and over again hoping that the
rehashing completed (and no new rehashing started in the mean time) ...

Please use something other than ENOMEM as it is already heavily
used in this context.  Perhaps EOVERFLOW?

We should probably add a WARN_ON_ONCE in rhashtable_insert_rehash
since two concurrent rehashings indicates something is going
seriously wrong.

Thanks,
-- 
Email: Herbert Xu [off-list ref]
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