Messages in this thread | | | Date | Sun, 27 Nov 2005 08:45:47 -0800 (PST) | From | Zwane Mwaikambo <> | Subject | Re: [PATCH] i386/x86_64: Don't IPI to offline cpus on shutdown |
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On Sun, 27 Nov 2005, Eric W. Biederman wrote:
> 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.
I wondered the same thing, perhaps i am papering over the bug, what exactly is do_exit doing there? - 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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