While creating pathological numbers of threads (to test whether bug 31617 is still an issue), I've managed to lock 2.4.2-2 sporadically. SysRq still works, but the keyboard seems to lock and the console no longer switches (all this from a plain VGA text console.) I couldn't reproduce this on 2.4.2-0.1.49.
Is this a lock or just the kernel being VERY slow ?
This was basically a complete lock -- I couldn't switch VT's and the keyboard indicators were unresponsive, which I've never seen before at the text console. The only thing that seemed to respond was sysrq. In regards to the original bug report, I've found this pretty difficult to reproduce. I've only been able to trigger it twice.
Closing: no reports of this with later errata kernels, if still present please reopen