Re: TUN problems (regression?)

Paul Moore
2012-12-21T16:28:29Z

On Thursday, December 20, 2012 03:38:17 PM Eric Dumazet wrote:
> On Thu, 2012-12-20 at 18:16 -0500, Paul Moore wrote:
> > [CC'ing netdev in case this is a known problem I just missed ...]
> >
> > Hi Jason,
> >
> > I started doing some more testing with the multiqueue TUN changes and I
> > ran
> > into a problem when running tunctl: running it once w/o arguments works as
> > expected, but running it a second time results in failure and a
> > kmem_cache_sanity_check() failure. The problem appears to be very
> > repeatable on my test VM and happens independent of the LSM/SELinux fixup
> > patches.
> >
> > Have you seen this before?
>
> Obviously code in tun_flow_init() is wrong...
>
> static int tun_flow_init(struct tun_struct *tun)
> {
> int i;
>
> tun->flow_cache = kmem_cache_create("tun_flow_cache",
> sizeof(struct tun_flow_entry),
> 0, 0, NULL);
> if (!tun->flow_cache)
> return -ENOMEM;
> ...
> }
>
>
> I have no idea why we would need a kmem_cache per tun_struct,
> and why we even need a kmem_cache.
>
>
> I would try following patch :
>
> drivers/net/tun.c | 24 +++---------------------
> 1 file changed, 3 insertions(+), 21 deletions(-)

Thanks, that solved my problem. Also, in case you were still curious, I was
using SLUB.

--
paul moore
security and virtualization @ redhat