Messages in this thread | | | Date | Wed, 20 Aug 2003 11:29:18 -0700 | From | Andrew Morton <> | Subject | Re: Dumb question: BKL on reboot ? |
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Hannes Reinecke <Hannes.Reinecke@suse.de> wrote: > > Hiya, > > I've got a dumb question: Why is the BKL held on entering sys_reboot() > in kernel/sys.c:405 ?
Probably for no good reason.
> It is getting especially interesting on SMP, when one cpu is entering > sys_reboot, acquires the BKL and then waits (via machine_restart) for > all other cpus to shut down. If any of the other cpus is executing a > task which also needs the BKL, we have a nice deadlock. > We've seen this here on 2-way s390, where the other cpu tried to execute > kupdated() (what did it try that for? Anyway...), which of course > resulted in a deadlock.
I guess that dropping the BKL around the machine_restart() call would be an appropriate 2.4 fix.
Where exactly does the rebooting CPU get stuck in machine_restart()? If someone has done lock_kernel() with local interrupts disabled then yes, it'll deadlock. But that's unlikely? Confused.
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