net_sched: qdisc_alloc_handle() can be too slow
When trying to allocate ~32768 qdiscs using autohandle mechanism, we can
fill the space managed by kernel (handles in [8000-FFFF]:0000 range)
But O(N^2) qdisc_alloc_handle() loops 0x10000 times instead of 0x8000
time tc add qdisc add dev eth0 parent 10:7fff pfifo limit 10
RTNETLINK answers: Cannot allocate memory
real 1m54.826s
user 0m0.000s
sys 0m0.004s
INFO: rcu_sched_state detected stall on CPU 0 (t=60000 jiffies)
Half number of loops, and add a cond_resched() call.
We hold rtnl at this point.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Dave Taht <dave.taht@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed