SMP forcing crash/reboot in 4.9-STABLE

[Alasdair Lumsden]

> This may be related to my problem, though the symptom is different.
> 
> Since the same time (around the end of november) i tried many times to
> build a SMP-enabled 4.9-STABLE kernel for my bi-athlon machine. It
always
> hangs (no error msg, total iresponsiveness) at the end of the kernel
boot
> (just before mounting filesystems).
> 
> I then reverted my cvs tree to use -RELEASE, and all is fine.
> 
> I did not yet try a non-SMP kernel. I'll do that asap.

Just a note - I believe SMP+APIC causes IRQ routing to be handled
differently compared with a non SMP kernel. We had a problem on one of
our boxes where after enabling SMP, the box would hang when trying to
mount the file systems.

The cause was traced to the raid card we had installed, which was in a
riser card off of the motherboard (Rackmount server). Plugging the raid
card directly into the motherboard resolved the problem, as did moving
the card to the bottom slot of the riser card.

I have no idea if this is related to your problem, but it did take us
hours of troubleshooting to work out this was what was wrong.