From: David Ahern dsahern@gmail.com
[ Upstream commit 64c6f4bbca748c3b2101469a76d88b7cd1c00476 ]
Ian and Alan both reported seeing overflows after upgrades to 5.x kernels: neighbour: arp_cache: neighbor table overflow!
Alan's mpls script helped get to the bottom of this bug. When a new entry is created the gc_entries counter is bumped in neigh_alloc to check if a new one is allowed to be created. ___neigh_create then searches for an existing entry before inserting the just allocated one. If an entry already exists, the new one is dropped in favor of the existing one. In this case the cleanup path needs to drop the gc_entries counter. There is no memory leak, only a counter leak.
Fixes: 58956317c8d ("neighbor: Improve garbage collection") Reported-by: Ian Kumlien ian.kumlien@gmail.com Reported-by: Alan Maguire alan.maguire@oracle.com Signed-off-by: David Ahern dsahern@gmail.com Tested-by: Alan Maguire alan.maguire@oracle.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/neighbour.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -663,6 +663,8 @@ out: out_tbl_unlock: write_unlock_bh(&tbl->lock); out_neigh_release: + if (!exempt_from_gc) + atomic_dec(&tbl->gc_entries); neigh_release(n); goto out; }