Happened again. strace shows this happening over and over. Two cores are 100% this time. steve getegid32() = 0 getegid32() = 0 getegid32() = -1 EAGAIN (Resource temporarily unavailable) getegid32() = -1 EAGAIN (Resource temporarily unavailable) getegid32() = 0 write(47, ptrace: umoven: Input/output error 0xffffffff, 119456880) = 0 write(47, ptrace: umoven: Input/output error 0xffffffff, 119456880) = 0 write(47, ptrace: umoven: Input/output error 0xffffffff, 119456848) = 0 write(47, ptrace: umoven: Input/output error 0xffffffff, 119456848) = 0