Eric W. Biederman wrote:
Daniel Lezcano <dlezcano@xxxxxxxxxx> writes:
When a network namespace reference is held by a network subsystem,
and when this reference is decremented in a rcu update callback, we
must ensure that there is no more outstanding rcu update before
trying to free the network namespace.
In the normal case, the rcu_barrier is called when the network namespace
is exiting in the cleanup_net function.
But when a network namespace creation fails, and the subsystems are
undone (like the cleanup), the rcu_barrier is missing.
This patch adds the missing rcu_barrier.
Looks sane. Did you have any specific failures related to this or was
this something that was just caught in review?
Yes, I had this problem when doing ipv6 isolation for netns49. The ipv6
subsystem creation failed and the different subsystem where rollbacked
in the setup_net function.
When the network namespace was about to be freed in free_net function, I
had the error with an usage refcount different from zero.
It appears that was coming from core/neighbour.c
neigh_parms_release
-> neigh_rcu_free_parms
-> neigh_parms_put
-> neigh_parms_destroy
-> release_net
The free_net function was called before rcu callback neigh_rcu_free_parms.
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