On Thu, Jun 11, 2020 at 09:23:52PM -0700, Matt Turner wrote: > Since I noticed earlier that using maxcpus=1 on a 2-CPU system > prevented the system from hanging, I tried disabling CONFIG_SMP on my > 1-CPU system as well. In doing so, I discovered that the RCU torture > module (RCU_TORTURE_TEST) triggers some null pointer dereferences on > Alpha when CONFIG_SMP is set, but works successfully when CONFIG_SMP > is unset. > > That seems likely to be a symptom of the same underlying problem that > started this thread, don't you think? If so, I'll focus my attention > on that.
I wonder if that is related to user space segfaults we are now seeing on SMP systems but not UP systems while building Alpha debian-ports. It's happening in the test-suites of builds of certain software (such as autogen and guile) but they always build successfully with the test suite passing on a UP system. When investigating I seem to recall it was a NULL (or near NULL) pointer dereference but couldn't make any sense of how it might have got into such an obviously wrong state. Cheers, Michael.
