The OpenVZ Linux kernel team has found deadlock between ptrace and coredump code. It affects 2.6.18 but does not affect the upstream kernel. "ptrace_start() spins waiting for child->state == TASK_TRACED/TASK_STOPPED. If we race with the coredumping, we have to wait until it completes. If the tracer participates in coredumping too, we deadlock. do_coredump() waits for tracer to exit and report complete(mm->core_startup_done), the tracer spins in an endless loop. Change ptrace_start() to abort if child->mm->core_waiters != 0." Patch: https://bugzilla.redhat.com/attachment.cgi?id=346742 Reference: https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2009-1388