Messages in this thread | | | Date | Sun, 2 Oct 2011 12:50:23 -0700 | From | Tejun Heo <> | Subject | Re: [BUGFIX][PATCH] Freezer, CPU hotplug, x86 Microcode: Fix task freezing failures |
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Hello,
On Mon, Oct 03, 2011 at 12:35:04AM +0530, Srivatsa S. Bhat wrote: > So, this patch addresses this issue by ensuring that microcode is not freed > from kernel memory, nor invalidated when a CPU goes offline. Thus once the > kernel gets the microcode during boot-up, it will never have to depend on > userspace ever again to get microcode, since it never releases the copy it > already has. So every run of the microcode callback for CPU online event will > now succeed irrespective of whether userspace is frozen or not. As a result, > this fixes the task freezing failure encountered while running CPU hotplug > stress test along with suspend/resume operations simultaneously.
I'm not familiar with how microcode is supposed to be managed but is it impossible for the newly hotplugged CPU (an actual hot unplug / plug) may not like the microcode loaded for the previous CPU? Isn't that why CPU_DEAD was invalidating the microcode?
Thanks.
-- tejun
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