Re: "swap_free: Unused swap offset entry 00000100" but no crash?

[Marcelo Tosatti <marcelo.tosatti@cyclades.com>]

On Tue, Jul 27, 2004 at 07:53:04AM -0500, Robin Holt wrote:
> On Tue, Jul 27, 2004 at 10:30:02PM +1000, Keith Owens wrote:
> > On Tue, 27 Jul 2004 02:21:54 +0200, 
> > Marcin Owsiany <marcin@owsiany.pl> wrote:
> > >    kernel: swap_free: Unused swap offset entry 00000100
> > >Also, I would be grateful if someone could explain what is that number in the
> > >message supposed to be? An address?
> > 
> > It is a swap partition number, but I doubt that you have 256 swap
> > partitions in your system.  Single bit set in a word that is meant to
> > be 0, most likely to be caused by a hardware single bit error.  Run
> > memtest, burn86 or other memory verification checks.
> > 
> 
> I remember a race condition I thought was possible, but couldn't exactly
> pin down the exact sequence.  Give me a chance to dig through some of
> my notes and see what I come across.

Would love to hear more details about this.

> I think I could understand this if there two messages with each invocation,
> but not with one.
> 
> Marcin, you have a process with a Page Table Entry which indicates it is
> pointing to a page which has been swapped out to block 0 of swap device
> 256.  This is probably caused by a problem in the kernel.  You can certainly
> run memtest et al.  If you don't find anything, I would assume the problem
> is in the kernel.

Marcin, please run the memtest86 and report back.

> Most of the code in the area you would be affected by has changed
> drastically in the 2.6 kernel.