Is "vm_fault" a kernel bug here?

[Dan Nelson]

In the last episode (Dec 08), Kris Kennaway said:
> On Mon, Dec 08, 2003 at 10:22:30PM +0100, Martin wrote:
> > Here is the result of a read access on a file, which is obviously
> > unreadable:
> > 
> > acd0: FAILURE - READ BIG status=51<READY,DSC,ERROR> sensekey=MEDIUM
> > ERROR error=4<ABORTED>
> > vm_fault: pager read error, pid 606 (cp)
> > cp: filename: Bad address
> > 
> > I want to report it, because of the "vm_fault", it sounds "scary".
> > Is this a correct behaviour or a bug in the kernel?
> 
> That's just what happens when an error is detected by the disk
> driver. This can be caused by hardware failure or incompatibility, or
> a driver bug.

More specifically, you get a vm_fault if the kernel is trying to page
in a block of memory for a process but can't.  The reason you get this
instead of a regular read error is because cp uses mmap() on files
smaller than 8 MB.

-- 
	Dan Nelson
	dnelson at allantgroup.com