Thanks for the precision. So logically we should expect it to break sooner or later ?
It is the same .config as one that crashed before, except that it has DEBUG_SLAB defined. If it does not crash, then adding pci=noacpi to the command fixes the problem for me.
Hmm, I'm not fully convinced yet, however glad that it has been a bit more stable for you.
Sidenote: We boot our systems having built-in AIC7* SCSI on moderately cheap motherboards with "bad" interrupt routing using pci=noacpi on 2.4.x kernels to evade instability.
I suggest that if you experience more problems using this setup _and_ would like to continue debugging the issue, we take this off-list into a private discussion.
[Another thing which would be interesting to test regarding the HIGHIO setting is a RedHat based 2.4.x kernel, since according to some SCSI driver's documentation, RedHat had a different HIGHIO convention.]