Messages in this thread | | | Date | Thu, 7 Nov 2019 15:38:48 +0000 | From | Quentin Perret <> | Subject | Re: NULL pointer dereference in pick_next_task_fair |
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On Thursday 07 Nov 2019 at 14:26:28 (+0100), Peter Zijlstra wrote: > Given that we're stuck with this order, the only solution is fixing > the 'change' pattern. The simplest fix seems to be to 'absuse' > p->on_cpu to carry more state. Adding more state to p->on_rq is > possible but is far more invasive and also ends up duplicating much of > the state we already carry in p->on_cpu.
I think there is another solution, which is to 'de-factorize' the call to put_prev_task() (that is, have each class do it). I gave it a go and I basically end up with something equivalent to reverting 67692435c411 ("sched: Rework pick_next_task() slow-path"), which isn't the worst solution IMO. I'm thinking at least we should consider it.
Now, 67692435c411 _is_ a nice clean-up, it's just a shame that the fix on top isn't as nice (IMO). It might just be a matter of personal taste, so I don't have a strong opinion on this :)
Thanks, Quentin
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