[Haifux] Kernel oops, so what?

Eli Billauer eli at billauer.co.il
Sat Jan 16 13:04:51 MSK 2010

Kohn Emil Dan wrote:
> No, it isn't. Crashing is one of the best of the options in some 
> situations. Imagine a bug in the filesystem that writes a zero byte at 
> random places on the filesystem or even funnier, on the neighboring 
> partitions where you have installed another operating system. (yes I 
> made one such bug once but I did not have another OS installed on 
> other partitions;-). This won't crash the kernel too fast. But the 
> consequences are not funny at all.
If I had my own homecooked filesystem driver in the kernel I would be 
more alert about oopses, yes. Actually, if I had anything untested in my 

And I happen to share this paranoia, that if something went wrong with 
the kernel surely my computer will explode here and now. But having been 
through some nasty crashes, I've learned that the damage is usually no 
more than the reboot.

I suppose it's a tradeoff between crashing here and now, leaving files 
in an inconsistent state, or just going on. Forcing a reboot or warmly 
suggesting one would be an elegant solution, though. It's interesting, 
that Red Hat, which takes the Enterprise Approach, choose to leave 
things as is (I'm on Fedora 12).

And here's a little twist: We seem to agree that the kernel can mess up 
the filesystem, but it just so happens that I've just restored much of 
my /usr directory from backup (I'm so lucky I had one handy) after 
inventing my own variant on the rm -rf / stunt. If case you wonder, I 
mounted my (still used) root directory over NFS on the new computer just 
to check something. The mount point was inside the home directory of a 
temporary user, which I chose to remove, including the home directory 
without first unmounting. And I didn't understand why removing the user 
took so much time.

So there I am again: The kernel can mess things up, my computer can be 
attacked, and aliens can invade my CPU. But in the end, it's my own 
stupid mistake that almost wiped a lot of dear files. I was merely lucky 
/home wasn't reached.


Web: http://www.billauer.co.il

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