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Andi Kleen <ak@suse.de> writes: > On Sun, Nov 27, 2005 at 02:05:45AM -0800, Zwane Mwaikambo wrote: >> http://bugzilla.kernel.org/show_bug.cgi?id=5203 >> >> There is a small race during SMP shutdown between the processor issuing >> the shutdown and the other processors clearing themselves off the >> cpu_online_map as they do this without using the normal cpu offline >> synchronisation. To avoid this we should wait for all the other processors >> to clear their corresponding bits and then proceed. This way we can safely >> make the cpu_online test in smp_send_reschedule, it's safe during normal >> runtime as smp_send_reschedule is called with a lock held / preemption >> disabled. > > Looking at the backtrace in the bug - how can sys_reboot call do_exit??? > I would say the problem is in whatever causes that. It shouldn't > do that. sys_reboot shouldn't schedule, it's that simple. > Your patch is just papering over that real bug. sys_reboot in the case of halt (after everything else is done) has directly called do_exit for years. There are some very subtle interactions there. The one I always remember (having found it the hard way) is that interrupts must be left on so ctrl-alt-del still works. This do_exit may be something similar, although I can't think of how it could be useful. Eric - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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