Mr Cascardo, If this is at a customer site, there is a workaround available for you.
In file /etc/modprobe.d/mlx4_core.conf, enter a line: options mlx4_core internal_err_reset=0 (do "modinfo mlx4_core" to see a description of the module parameter). Setting this parameter to 0 in the modprobe conf file will cause the driver to simply report the internal error failure (in /var/log/messages), but the device will not be restarted. This will avoid your Oops -- the EEH flow will then be the only flow restarting the device. (Note that even if you implement my suggestion, you will still have a situation where the device will be reset TWICE). Again, this is a workaround for current users. The issue needs to be fixed so that even when the internal error does cause a reset, the kernel will not crash. Unfortunately, I do not have the time now to generate a patch. -Jack On Wednesday 29 February 2012 17:19, Jack Morgenstein wrote: > On Wednesday 29 February 2012 16:47, Jack Morgenstein wrote: > > Some comments. > > > > 1. Mr Cascardo's solution is only partial, and does not cover all the > > problem cases. He > > simply uncovered one of several examples of what lack-of-sync will do > > when removing a device. > > Mr. Cascardo found the kernel Oops that happens when a catastrophic > > error occurs during device > > removal. What if we receive a catas error while doing "init_one"? What > > if we are in the middle > > of catas error recovery (in the init_one stage), and we get a remove_one > > request from higher up? > > > > There is a solution for this precise problem in the mthca driver > > (infiniband/hw/mthca/mthca_main.c > > infiniband/hw/mthca/mthca_catas.c). In the mthca driver, we DO in fact > > use an "mthca_device_mutex" > > for precisely the reason given in a. above. I see no reason not to do > > the same thing here. > > > > This requires: > > 1. mlx4_init_one(), mlx4_remove_one() and mlx4_restart_one all grab an > > mlx4_device_mutex. > > 2. new procedure __mlx4_remove_one(), which does not grab the mutex. > > > > Note that it is NOT enough to simply protect the removal operation. The > > protection must wrap the > > ENTIRE restart operation (both removal and init), because allowing a > > remove in the middle of init_one > > or restart_one would probably also cause a kernel Oops. > > > > 2. The intf_mutex is used with mlx4_un/register_device and > > mlx4_un/register_interface. unregister_device is > > used both in remove_one and in mlx4_change_port_types. I would hesitate > > to grab that mutex for a more > > global use. I think it is cleaner to add a device mutex > > (mlx4_device_mutex) for initializing/removing/ > > restarting the device. > > > > -Jack > > > Another thing -- what about the desired final state of the device? Say we do > a remove one, and in the middle > of this, we get a catas restart. The catas restart will wait until the > remove-in-progress completes, and > then will do its remove/init -- with the net result that the device is UP > rather than DOWN. > > This implies that we need some sort of state machine here. > > -Jack > -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
