On Thu, Nov 15, 2007 at 01:29:04PM -0500, Mark Lord wrote: > Greg KH wrote: >> On Thu, Nov 15, 2007 at 12:07:48PM -0500, Mark Lord wrote: > .. >>> Greg, I don't know if this is relevant or not, >>> but x86 has bugs in the halt/reboot code for SMP. >>> >>> Specifically, in native_smp_send_stop() the code now uses >>> spin_trylock() to "lock" the shared call buffers, >>> but then ignores the result. >>> >>> This means that multiple CPUs can/will clobber each other >>> in that code. >>> >>> The second bug, is that this code does not wait for the >>> target CPUs to actually stop before it continues. >>> >>> This was the real cause of the failure-to-poweroff problems >>> I was having with 2.6.23, which we fixed by using CPU hotplug >>> to disable_nonboot_cpus() before the above code ever got run. >> I have noticed that the shutdown path is quite weird, shutting down >> sysdev devices differently depending on the type of shutdown, which is >> probably not good. >> But what change are you talking about for the poweroff problem? I have >> a _lot_ of people reporting that 2.6.22 is not powering off for them and >> I can't seem to figure it out. Do you have a changeset for something >> that went in to fix this issue? > .. > > Well, the real bugs that cause the problem are described by me above. > I don't have a fix for those, but the workaround is in 2.6.23 > under git 4047727e5ae33f9b8d2b7766d1994ea6e5ec2991 Fix SMP poweroff hangs. > > With that workaround, there's no more hanging on halt, > though there could still be a hang on reboot. > > A problem with that workaround is that it has no effect unless > the CPU hotplug code is configured (CONFIG_PM_SLEEP_SMP and pals).
Hm, that's not going to be a fix for 2.6.22 as we already do a call to that function in that call when shutting down, something in the 2.6.23-rc series must have changed that logic to make it required again. Oh well, thanks anyway, I'll keep trying to track this down. greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/