From: Firo Yang firo.yang@suse.com
[ Upstream commit 0f90522591fd09dd201065c53ebefdfe3c6b55cb ]
Recent months, our customer reported several kernel crashes all preceding with following message: NETDEV WATCHDOG: eth2 (enic): transmit queue 0 timed out Error message of one of those crashes: BUG: unable to handle kernel paging request at ffffffffa007e090
After analyzing severl vmcores, I found that most of crashes are caused by memory corruption. And all the corrupted memory areas are overwritten by data of network packets. Moreover, I also found that the tx queues were enabled over watchdog reset.
After going through the source code, I found that in enic_stop(), the tx queues stopped by netif_tx_disable() could be woken up over a small time window between netif_tx_disable() and the napi_disable() by the following code path: napi_poll-> enic_poll_msix_wq-> vnic_cq_service-> enic_wq_service-> netif_wake_subqueue(enic->netdev, q_number)-> test_and_clear_bit(__QUEUE_STATE_DRV_XOFF, &txq->state) In turn, upper netowrk stack could queue skb to ENIC NIC though enic_hard_start_xmit(). And this might introduce some race condition.
Our customer comfirmed that this kind of kernel crash doesn't occur over 90 days since they applied this patch.
Signed-off-by: Firo Yang firo.yang@suse.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/ethernet/cisco/enic/enic_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/net/ethernet/cisco/enic/enic_main.c +++ b/drivers/net/ethernet/cisco/enic/enic_main.c @@ -1807,10 +1807,10 @@ static int enic_stop(struct net_device * }
netif_carrier_off(netdev); - netif_tx_disable(netdev); if (vnic_dev_get_intr_mode(enic->vdev) == VNIC_DEV_INTR_MODE_MSIX) for (i = 0; i < enic->wq_count; i++) napi_disable(&enic->napi[enic_cq_wq(enic, i)]); + netif_tx_disable(netdev);
if (!enic_is_dynamic(enic) && !enic_is_sriov_vf(enic)) enic_dev_del_station_addr(enic);