Re: Dmesg filled with "AER: Corrected error received"

[Bjorn Helgaas <helgaas@kernel.org>]

On Fri, Dec 18, 2015 at 11:30:33AM +0100, David Henningsson wrote:
> Hi Linux PCI maintainers,
> 
> My dmesg gets filled with a few lines repeated over and over again:
> 
> pcieport 0000:00:1c.0: AER: Corrected error received: id=00e0
> pcieport 0000:00:1c.0: can't find device of ID00e0
> pcieport 0000:00:1c.0: AER: Corrected error received: id=00e0
> pcieport 0000:00:1c.0: PCIe Bus Error: severity=Corrected,
> type=Physical Layer, id=00e0(Receiver ID)
> pcieport 0000:00:1c.0:   device [8086:9d14] error
> status/mask=00000001/00002000
> pcieport 0000:00:1c.0:    [ 0] Receiver Error
> 
> This happens 10-30 times per second (!), so dmesg fills up quickly.
> The bug is present in both vanilla and Ubuntu kernels.

This is a pretty obvious bug in our AER code.  We normally clear
correctable errors by writing the PCI_ERR_COR_STATUS register in
handle_error_source().  The execution path looks like this:

  aer_isr_one_error
    aer_print_port_info
    if (find_source_device())
      aer_process_err_devices
        handle_error_source
          pci_write_config_dword(dev, PCI_ERR_COR_STATUS, ...)

In this case, find_source_device() printed "can't find device of
ID00e0" [sic] and returned false, so we don't call
aer_process_err_devices().  The error is never cleared, so
we discover it again and again.

I'll work on fixing this.  Incidentally, there's another report
with similar symptoms here:

  https://bugzilla.kernel.org/show_bug.cgi?id=109691

Bjorn