Messages in this thread Patch in this message | | | Date | Sun, 24 Mar 2002 18:48:28 -0800 | From | Andrew Morton <> | Subject | Re: preempt-related hangs |
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Anton Altaparmakov wrote: > > At 02:11 25/03/02, Andrew Morton wrote: > >Andrew Morton wrote: > > > > > > .. > > > Kernel is 2.5.7, dual PIII. When I enable preempt it > > > locks during boot. > > > >OK, this patch fixed it. I don't know why. > > Er, because you disable preemption twice and it never gets enabled again? (-: > > You probably meant that to be preemt_enable() at the bottom of the patch... > That might not solve your problem of course... But with the patch you > basically have completely disabled preemption, you might as well not > configure it into the kernel. (-;
Yeah I know. Sheesh. I don't even have time to test the fix before you're on my act :)
Fixed-up workaround with a little debug check is below.
I think Robert's right - the problem is more likely to lie with the migration thread handoff thingy.
--- 2.5.7/kernel/sched.c~preempt-lockup Sun Mar 24 18:10:49 2002 +++ 2.5.7-akpm/kernel/sched.c Sun Mar 24 18:25:29 2002 @@ -1561,6 +1561,8 @@ void set_cpus_allowed(task_t *p, unsigne migration_req_t req; runqueue_t *rq; + preempt_disable(); + new_mask &= cpu_online_map; if (!new_mask) BUG(); @@ -1573,7 +1575,7 @@ void set_cpus_allowed(task_t *p, unsigne */ if (new_mask & (1UL << p->thread_info->cpu)) { task_rq_unlock(rq, &flags); - return; + goto out; } init_MUTEX_LOCKED(&req.sem); @@ -1583,6 +1585,8 @@ void set_cpus_allowed(task_t *p, unsigne wake_up_process(rq->migration_thread); down(&req.sem); +out: + preempt_enable(); } static volatile unsigned long migration_mask; --- 2.5.7/kernel/exit.c~preempt-lockup Sun Mar 24 18:31:39 2002 +++ 2.5.7-akpm/kernel/exit.c Sun Mar 24 18:37:19 2002 @@ -489,6 +489,14 @@ NORET_TYPE void do_exit(long code) panic("Attempted to kill the idle task!"); if (tsk->pid == 1) panic("Attempted to kill init!"); +#ifdef CONFIG_PREEMPT + if (preempt_get_count()) { + printk(KERN_ERR "task `%s' exits with non-zero " + "preempt count: %d\n", + current->comm, + preempt_get_count()); + } +#endif tsk->flags |= PF_EXITING; del_timer_sync(&tsk->real_timer); - - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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