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is it possible that printk cause deadlock? the path is as below:
1. taskA runs on CPU0, and run schedule to acqire the rq->lock. 2. taskA calls printk while holding rq->lock. 3. taskA holds console_sem. 4. taskB runs on CPU1, and call console_lock(), which is blocked by console_sem and queue itslef to the wait list. 5. taskB migrates from CPU1 to cpu0. will this step occur? 6. taskA calls up(&console_sem)--> wake_up_process()-->try_to_wake_up()-->ttwu_queue()-->raw_spin_lock(&rq->lock). here taskA tries to acquire the rq->lock of CPU0 again. |
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