Messages in this thread | | | Date | Wed, 8 Oct 2014 17:48:38 +0200 | From | Peter Zijlstra <> | Subject | Re: [trace events] WARNING: CPU: 0 PID: 91 at kernel/sched/core.c:7253 __might_sleep() |
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On Wed, Oct 08, 2014 at 11:08:25AM -0400, Steven Rostedt wrote: > > Steve, wth is that thing supposed to do? > > > > set_current_state(TASK_INTERRUPTIBLE); > > while (!kthread_should_stop()) > > schedule(); > > > > That looks broken alright. It'll revert to a yield() 'spin' loop if it > > ever gets a wakeup for anything other than the kthread_stop(). > > > > Did you mean to write something like: > > > > set_current_state(TASK_INTERRUPTIBLE); > > while (!kthread_should_stop()) { > > schedule(); > > set_current_state(TASK_INTERRUPTIBLE); > > } > > __set_current_state(TASK_RUNNING); > > > > ? > > Wow, what a blast from the past. That code hasn't been touched since > 2009! > > Anyway, all that thread did was call test work on each cpu, and then > waits to be killed. It should only get a single wake up and that should > be from the kthread_stop() call. IOW, that loop should never be > executed more than once. > > What exactly is the bug here?
The bug is as explained, the loop is wrong and will revert to a yield 'spin' loop after a single wakeup.
The debugging that caught it is that you exit the loop without setting TASK_RUNNING.
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