On Thu, 2002-04-04 at 14:14, Linus Torvalds wrote:
> The answer is that preempt_schedule() illegally sets
>
> current->state = TASK_RUNNING;
>
> without asking the process whether that's ok. The SMP code never does
> anything like that.
Well Ingo added that ;)
We used to just set a flag in the preempt_count that marked the task as
preempted and made sure on its next trip into schedule it ran again.
Do you think it is better to deny preemption if state==TASK_ZOMBIE (note
this requires code in preempt_schedule and the interrupt return path,
since Ingo decoupled the two) or just disable preemption around critical
regions caused by setting state to TASK_ZOMBIE ?
I suspect this is the first occurrence of a problem of this kind ... and
the attached patch handles it.
Robert Love
diff -urN linux-2.5.8-pre1/kernel/exit.c linux/kernel/exit.c
--- linux-2.5.8-pre1/kernel/exit.c Wed Apr 3 20:57:37 2002
+++ linux/kernel/exit.c Thu Apr 4 14:22:30 2002
@@ -499,6 +499,8 @@
acct_process(code);
__exit_mm(tsk);
+ preempt_disable();
+
sem_exit();
__exit_files(tsk);
__exit_fs(tsk);
@@ -515,6 +517,7 @@
tsk->exit_code = code;
exit_notify();
+ preempt_enable_no_resched();
schedule();
BUG();
/*
-
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This archive was generated by hypermail 2b29 : Sun Apr 07 2002 - 22:00:14 EST