Red Hat Bugzilla – Bug 157424
U1 kernel 2.6.9-6.37.EL ptrace panics
Last modified: 2007-11-30 17:07:18 EST
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Description of problem:
kernel panic in ptrace
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. run gdb
Actual Results: kernel panic
This happens a few times per week under heavy debug load.
Created attachment 114247 [details]
Created attachment 114248 [details]
Yeah, looks obvious. We don't do the lazy fpu saving on SMP machines, and we
object violently to being asked to save the FPU for a non-current task.
Hm. Actually I'm unconvinced the above is anything more than a workaround. The
BUG() will only trigger if MSR_FP is enabled for the child, and that really
shouldn't be happening.
*** Bug 157433 has been marked as a duplicate of this bug. ***
Fixing kernel version and assigning.
Created attachment 114293 [details]
This is the real fix. The problem we weren't correctly waiting for the inferior
to be taken off its CPU. Its register set really was in some other CPU, not in
the place we were looking for it, and that's why the FPU was still marked as
*** Bug 157831 has been marked as a duplicate of this bug. ***