Messages in this thread | | | Date | Thu, 15 Nov 2007 14:13:22 -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 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. ..
But remember, it has no effect unless the kernel has suspend/resume configured in. Many desktops don't.
And the real unfixed bugs are still there in native_smp_send_stop() as described above. You could prod whoever takes care of that code to fix them.
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