Messages in this thread | | | Date | Tue, 1 Sep 2009 18:00:44 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] kthreads: Fix startup synchronization boot crash |
| |
On 09/01, Ingo Molnar wrote: > > * Oleg Nesterov <oleg@redhat.com> wrote: > > > But I must admit, now I don't understand what happens, > > > > The modification of that variable is protected by the BKL, but > > the _ordering_ of the initial task (which becomes the idle > > thread of CPU0) and the init task (which is spawned by the > > initial task) is not synchronized. > > > > So we can occasionally end up init running sooner than > > rest_init() > > > > How? rest_init() can't be preempted and it holds BKL. And > > kernel_init() takes BKL before anything else. Confused... > > it cannot be preempted but it can schedule anywhere - and the BKL > will be dropped silently. > > This is one of the biggest dangers of the BKL
Yes I see. But rest_init() runs under preempt_disable(). If it was rescheduled, schedule_debug() should complain. No?
Oleg.
| |