net: increase IP_TUNNEL_RECURSION_LIMIT to 5

In configurations with multiple tunnel layers and MPLS lwtunnel routing, a
single tunnel hop can increment the counter beyond this limit. This causes
packets to be dropped with the "Dead loop on virtual device" message even
when a routing loop doesn't exist.

Increase IP_TUNNEL_RECURSION_LIMIT from 4 to 5 to handle this use-case.

Fixes: 6f1a9140ecda ("net: add xmit recursion limit to tunnel xmit functions")
Link: https://lore.kernel.org/netdev/88deb91b-ef1b-403c-8eeb-0f971f27e34f@redhat.com/
Signed-off-by: Chris J Arges <carges@cloudflare.com>
Link: https://patch.msgid.link/20260402222401.3408368-1-carges@cloudflare.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index 1f577a4f8ce9b1ae4223d9cfd903bec8d7d78c04..d708b66e55cda514be60643afb14710705d5ba82 100644 (file)
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h
@@ -32,7 +32,7 @@
  * recursion involves route lookups and full IP output, consuming much
  * more stack per level, so a lower limit is needed.
  */
-#define IP_TUNNEL_RECURSION_LIMIT      4
+#define IP_TUNNEL_RECURSION_LIMIT      5
 
 /* Keep error state on tunnel for 30 sec */
 #define IPTUNNEL_ERR_TIMEO     (30*HZ)