Re: [Experimental CPU Hotplug PATCH] - Move migrate_all_tasks toCPU_DEAD handling

[Rusty Russell]

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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