Hi Tejun & Jiangshan, I find an null pointer risk in the code of workqueue. Here is description:
If draining, __queue_work() will call the function is_chained_work() to do some checks. In is_chained_work(), worker->current_pwq is used directly. It should be not safe. http://elixir.free-electrons.com/linux/latest/source/kernel/workqueue.c#L1384 If you check the thread function of this worker, worker_thread(), you will find worker->current_pwq is null when one work is done or ready to be processed. This issue may happen only if we queue work during executing drain_workqueue(). http://elixir.free-electrons.com/linux/latest/source/kernel/workqueue.c#L2173 There are very few places to call drain_workqueue() in the whole linux kernel. I think that's why no one noticed this risk. Xiaofei Tan _______________________________________________ linuxarm mailing list linux...@huawei.com http://rnd-openeuler.huawei.com/mailman/listinfo/linuxarm .
