Messages in this thread | | | Subject | Re: [Experimental CPU Hotplug PATCH] - Move migrate_all_tasks to CPU_DEAD handling | From | Rusty Russell <> | Date | Wed, 07 Apr 2004 13:54:34 +1000 |
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On Tue, 2004-04-06 at 19:26, Nick Piggin wrote: > Note there was already that check in the wakeup path, although > I suspect it was someone being overly cautious and isn't required.
No, it really is required.
The stop_machine thread runs on the cpu, then kicks everyone else off, then does a complete() (in stop_machine.c:do_stop()). Without this check, the complete() drags the sleeping process (which called stop_machine) onto the dying CPU.
Hmm, maybe we could explicitly exclude downed cpu from calling task's mask. Kind of hacky: theoretically you should never modify a task's affinity unless the user actually asked for it (since anyone can ask for another tasks affinity).
Cheers! Rusty. -- Anyone who quotes me in their signature is an idiot -- Rusty Russell
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