Messages in this thread |  | | Date | Fri, 30 Aug 2002 09:06:38 +0200 (CEST) | From | Ingo Molnar <> | Subject | Re: 2.5.32: DEBUG_SLAB and PREEMPT = constant oops in schedule() |
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On Thu, 29 Aug 2002, Christian Ehrhardt wrote:
> sys_sched_setaffinity, lines: > 1571 get_task_struct(p); > 1572 read_unlock(&tasklist_lock);
> Line 1571 calls get_task_struct because the task might exit during the > syscall. Suppose that this is exactly what happens. This means that line > 1583 will effectivly free the task. But set_cpus_allowed stuffed a > pointer to the task into a request struct without incrementing the usage > count of the task struct.
note that the scenario you describe is not possible, because set_cpus_allowed() will wait for the migration thread to do its work - so the put_task_struct can never come before the last use of the task structure. See the 'down(&req.sem)' in set_cpus_allowed(), and the up(&req->sem) in migration_thread().
Ingo
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