On Wed, 31 Oct 2007 17:40:06 -0400 Andrew Gallatin <[EMAIL PROTECTED]> wrote:
> > When testing the myri10ge driver with 2.6.24-rc1, I found > that the machine crashed under heavy load: > > Unable to handle kernel paging request at 0000000000100108 RIP: > [<ffffffff803cc8dd>] net_rx_action+0x11b/0x184 > > The address corresponds to the list_move_tail() in > netif_rx_complete(): > if (unlikely(work == weight)) > list_move_tail(&n->poll_list, list); > > Eventually, I traced the crashes to calling netif_rx_complete() with > work_done == budget. From looking at other drivers, it appears that > one should only call netif_rx_complete() when work_done < budget. > > To fix it, I changed the test in myri10ge_poll() so that it refers > to to work_done rather than looking at the rx ring status. If > work_done is < budget, then that implies we have no more packets to > process. Any races will be resolved by the NIC when the write to > irq_claim is made. > > In myri10ge_clean_rx_done(), if we ever exceeded our budget, it would > report a work_done one larger than was acutally done. This is because > the increment was done in the conditional, so work_done would be > incremented regardless of whether or not the test passed or failed. > This would lead to the WARN_ON_ONCE(work > weight); warning in > net_rx_action triggering. I've moved the increment of work_done > inside the loop. Note that this would only be a problem when we had > exceeded our budget. > > Signed off by: Andrew Gallatin <[EMAIL PROTECTED]> > > Andrew Gallatin Myricom Inc > > Yes, this looks right. How could the check in netif_rx_complete be changed to catch this better? -- Stephen Hemminger <[EMAIL PROTECTED]> - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
