Red Hat Bugzilla – Bug 243311
printk in atomic can schedule
Last modified: 2008-02-27 14:56:25 EST
Description of problem:
printk calls consol functions that write to the appropriate devices.
But in the PREEMPT_RT kernel, some of these console functions grab
spin locks that are converted to mutexes. This means that calling
printk in an atomic operation or from interrupt contex can schedule
and cause undefined results.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
I need to write a patch that will add an ATOMIC_SAFE flag to the console
drivers. This will be checked if printk is called from an atomic
operation. If the console is not safe, then printk will skip that
console. Current consoles that should be atomic safe, is the VGA
console as well as early_printk console.