Messages in this thread | | | Date | Thu, 7 Nov 2019 20:31:34 +0100 | From | Peter Zijlstra <> | Subject | Re: NULL pointer dereference in pick_next_task_fair |
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On Thu, Nov 07, 2019 at 07:27:53PM +0000, Quentin Perret wrote: > On Thursday 07 Nov 2019 at 19:43:56 (+0100), Peter Zijlstra wrote: > > But you mean something like: > > > > for (class = prev->sched_class; class; class = class->next) { > > if (class->balance(rq, rf)) > > break; > > } > > > > put_prev_task(rq, prev); > > > > for_each_class(class) { > > p = class->pick_next_task(rq); > > if (p) > > return p; > > } > > > > BUG(); > > > > like? > > Right, something like that, though what I had was basically doing the > pull from within the pick_next_task_*() functions directly, like we were > doing before. I'm now seeing how easy it is to get this wrong, and that > even good-looking code in this area can be broken in very subtle ways, > so I didn't feel comfortable refactoring again so close to rc7. If you > feel more confident, I'm more than happy to test a patch implemeting the > above :)
Thing is, if we revert (and we might have to), we'll have to revert more than just the one patch due to that other (__pick_migrate_task) borkage that got reported today.
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