SMP Frequent Lockups

Jouni Malinen jkmaline at cc.hut.fi
Sat Aug 2 12:32:30 EDT 2003


On Fri, Aug 01, 2003 at 05:39:15PM +0000, Michael Vallaly wrote:

> I am having issues with my WPC11 Linksys PCI card and a 2.4.21 SMP kernel. I recently upgraded the machine with another processor and recompiled the kernel to support SMP. Previously ive had only 1 or 2 lockups (non SMP kernel) using Hostap 0.0.3 under heavy traffic (FTP for instance) over a 3 month span. Now with the SMP kernel I have lockups with even light usage of the wireless AP (ssh or webbrowsing). These are hard lockups that require cycling the power via unplugging. I can verify that the lockups only happen with some sort of traffic on the wireless card, as I can keep the hostap module loaded with the interface down, and not crash. Anyone have a solution? 

Could you please first verify couple of things:

1) if you boot non-SMP kernel and try the latest CVS version of Host AP
   driver, the host does not crash (at least frequently)
2) can you enable NMI watchdog? (see Linux kernel
   Documentation/nmi_watchdog.txt; verify that NMI counter increases in
   /proc/interrupts)

Unfortunately, I have been only able to test with hostap_cs and
hostap_plx on an SMP host and I was unable to crash the box. Since you
have a card using hostap_pci, it would be nice to get more testing on
that.

Before doing any changes to the driver, I would like to know whether you
can get any output from the lockup when using SMP-kernel. I would
suggest enabling NMI watchdog, moving to text mode, setting console
logging level to maximum ('dmesg -n 8'). Then do whatever is needed to
hang the system. Wait about 10 seconds and hope that something will be
printed on screen.

-- 
Jouni Malinen                                            PGP id EFC895FA



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