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Subject[PATCH] net: delete expired route in ip6_pmtu_deliver
The first big packets sent to a "low-MTU" client correctly
triggers the creation of a temporary route containing the reduced MTU.

But after the temporary route has expired, new ICMP6 "packet too big"
will be sent, rt6_pmtu_discovery will find the previous EXPIRED route
check that its mtu isn't bigger then in icmp packet and do nothing
before the temporary route will not deleted by gc.

I make the simple experiment:
while :; do
time ( dd if=/dev/zero bs=10K count=1 | ssh hostname dd of=/dev/null ) || break;
The "time" reports real 0m0.197s if a temporary route isn't expired, but
it reports real 0m52.837s (!!!!) immediately after a temporare route has
Signed-off-by: Andrey Vagin <>
net/ipv6/route.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 96455ffb..7659d6f 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1565,11 +1565,16 @@ static void rt6_do_pmtu_disc(struct in6_addr *daddr, struct in6_addr *saddr,
struct rt6_info *rt, *nrt;
int allfrag = 0;
rt = rt6_lookup(net, daddr, saddr, ifindex, 0);
if (rt == NULL)

+ if (rt6_check_expired(rt)) {
+ ip6_del_rt(rt);
+ goto again;
+ }
if (pmtu >= dst_mtu(&rt->dst))
goto out;


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