However, interrupt disabling alone does not always prevent kernel control path interleaving.
Indeed, a kernel control path could raise a “Page fault” exception, which in turn could suspend the current process (and thus the corresponding kernel control path). Or again, a kernelcontrol path could directly invoke the schedule( ) function. This happens during most I/O disk operations because they are potentially blocking, that is, they may force the process to sleep until the I/O operation completes. Therefore, the kernel must never execute a blocking operation when interrupts are disabled, since the system could freeze.
