Messages in this thread | | | Date | Mon, 14 Jun 2021 20:38:01 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] freezer,sched: Rewrite core freezer logic |
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On Mon, Jun 14, 2021 at 06:54:23PM +0200, Oleg Nesterov wrote: > On 06/14, Peter Zijlstra wrote:
> > > I guess you do this to avoid freezable_schedule() in ptrace/signal_stop, > > > and we can't use TASK_STOPPED|TASK_FREEZABLE, it should not run after > > > thaw()... But see above, we can't rely on __frozen(parent). > > > > I do this because freezing puts a task in TASK_FROZEN, and that cannot > > preserve TAKS_STOPPED or TASK_TRACED without being subject to wakups > > Yes, yes, this is what I tried to say.
OK, thanks for all that. Clearly I need to stare at this code longer and harder.
One more thing; if I add additional state bits to preserve __TASK_{TRACED,STOPPED}, then I need to figure out at thaw time if we've missed a wakeup or not.
Do we have sufficient state for that? If so, don't we then also not have sufficient state to tell if a task should've been TRACED/STOPPED in the first place?
If not, I probably should add this... I'll go dig.
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