Bird6 freeze under high load

[Ondrej Zajicek]

On Thu, Feb 05, 2015 at 03:07:07PM +0100, Baptiste Jonglez wrote:
> By the way, I think I found a kernel commit that should fix this issue:
> 
> commit 1c2658545816088477e91860c3a645053719cb54
> Author: Kumar Sundararajan <kumar at fb.com>
> Date:   Thu Apr 24 09:48:53 2014 -0400
> 
>     ipv6: fib: fix fib dump restart
> 
>     When the ipv6 fib changes during a table dump, the walk is
>     restarted and the number of nodes dumped are skipped. But the existing
>     code doesn't advance to the next node after a node is skipped. This can
>     cause the dump to loop or produce lots of duplicates when the fib
>     is modified during the dump.
> 
>     This change advances the walk to the next node if the current node is
>     skipped after a restart.
> 
>     Signed-off-by: Kumar Sundararajan <kumar at fb.com>
>     Signed-off-by: Chris Mason <clm at fb.com>
>     Signed-off-by: David S. Miller <davem at davemloft.net>
> 
>  net/ipv6/ip6_fib.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> 
> The patch is very simple... See also
> http://kernel.opensuse.org/cgit/kernel/commit/?id=1c2658545816088477e91860c3a645053719cb54
> 
> 
> Does Bird keep inserting routes in the kernel while it is scanning the
> routing table?  If so, then we probably hit this bug.

Hi

Thanks for noticing it.

We generally do not insert routes during the scan as scanning is an
undivided process in BIRD and all synchronization is done immediately
after the scan, but perhaps it is triggered anyways.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."
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