I am looking at version 3.4

? 2013-2-16?0:17?Valdis.Kletnieks at vt.edu ???

On Fri, 15 Feb 2013 17:17:38 +0530, anish singh said:

quoted

adding Joe Perches  as generally he looks after printk stuff.

On Fri, Feb 15, 2013 at 2:22 PM, buyitian [off-list ref] wrote:

quoted

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.

I'm not Joe, but what kernel release are you looking at?  ISTR that in
the last few releases (3.5-ish maybe?), that code got overhauled to
prevent a similar issue...
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