Messages in this thread | | | Date | Thu, 15 Nov 2007 13:29:04 -0500 | From | Mark Lord <> | Subject | Re: EIP is at device_shutdown+0x32/0x60 |
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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).
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