Messages in this thread | | | Date | Thu, 20 Feb 2003 20:00:26 +0100 (CET) | From | Ingo Molnar <> | Subject | Re: doublefault debugging (was Re: Linux v2.5.62 --- spontaneous reboots) |
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On Thu, 20 Feb 2003, Linus Torvalds wrote:
> > a true heisenbug. I cannot reproduce it anymore. Anyway, from the serial > > console i collected 3 instances of crashes - whatever it's worth. > > Pretty much every single time, release_task() has been there on the > backtrace. > > In fact, I bet you this code in do_exit() is the cause: > > preempt_disable(); > > if (tsk->exit_signal == -1) > *** release_task(tsk); *** > > schedule(); > > Note how "release_task()" will be releasing the stack that the process > is running on right now. [...]
but, release_task() is a delayed thing for exactly this reason. It fills out the per-CPU task_cache but does not free the task.
the release_task() + schedule() must be atomic though - ie. we must not be preempted anytime inbetween [because that other task could free the task_cache] - but i wasnt running with CONFIG_PREEMPT, so i cannot see how it could happen.
Ingo
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