Messages in this thread | | | Date | Thu, 7 Nov 2019 12:43:55 +0000 | From | Quentin Perret <> | Subject | Re: [sched] 10e7071b2f: BUG:kernel_NULL_pointer_dereference,address |
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On Thursday 07 Nov 2019 at 12:37:09 (+0000), Valentin Schneider wrote: > On 07/11/2019 12:15, Quentin Perret wrote: > > On Thursday 07 Nov 2019 at 12:09:22 (+0000), Quentin Perret wrote: > >> sched_move_task() follows what Peter called the 'change' pattern, so I'm > >> thinking this is most likely the same issue. Dropping the lock causes an > >> unmitigated race between sched_move_task() and pick_next_task_dl(), so > >> hilarity ensues (set_next_task() being called twice for instance). > > > > Bah, scratch that. 10e7071b2 is clearly before the pick_next_task() > > rework, so that's not it :( > > > > And besides we don't drop the lock until reaching pick_next_task_fair(), > and the splat says it died on pick_next_task_dl() which happens earlier.
Right, with the rework of pick_next_task(), we would in fact drop the lock before calling pick_next_task_dl(), which would explain the issue, hence my confusion.
But that doesn't apply here, so this is another problem :(
Sorry for the noise, Quentin
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