Messages in this thread | | | From | Roman Penyaev <> | Date | Tue, 25 Oct 2016 15:00:58 +0200 | Subject | Re: [PATCH v3 1/1] workqueue: ignore dead tasks in a workqueue sleep hook |
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On Tue, Oct 25, 2016 at 2:56 PM, Oleg Nesterov <oleg@redhat.com> wrote: > On 10/25, Roman Pen wrote: >> >> struct task_struct *wq_worker_sleeping(struct task_struct *task) >> { >> - struct worker *worker = kthread_data(task), *to_wakeup = NULL; >> + struct worker *worker, *to_wakeup = NULL; >> struct worker_pool *pool; >> >> + >> + if (task->state == TASK_DEAD) { >> + /* >> + * Here we try to catch the following path before >> + * accessing NULL kthread->vfork_done ptr thru >> + * kthread_data(): >> + * >> + * oops_end() >> + * do_exit() >> + * schedule() >> + * >> + * If panic_on_oops is not set and oops happens on >> + * a workqueue execution path, thread will be killed. >> + * That is definitly sad, but not to make the situation >> + * even worse we have to ignore dead tasks in order not >> + * to step on zeroed out members (e.g. t->vfork_done is >> + * already NULL on that path, since we were called by >> + * do_exit())). >> + */ >> + return NULL; >> + } > > I still think that PF_EXITING check makes more sense than TASK_DEAD, > but I won't insist.
Why? I probably do not see the corner cases, so, please, explain.
-- Roman
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