On Wed, Nov 14, 2018 at 12:55:20PM -0800, Florian Fainelli wrote: > On 3/9/17 7:18 AM, Steven Rostedt wrote: > > From: "Steven Rostedt (VMware)" <[email protected]> > > > > > > When priority inheritance was added back in 2.6.18 to sched_setscheduler, it > > added a path to taking an rt-mutex wait_lock, which is not IRQ safe. As PI > > is not a common occurrence, lockdep will likely never trigger if > > sched_setscheduler was called from interrupt context. A BUG_ON() was added > > to trigger if __sched_setscheduler() was ever called from interrupt context > > because there was a possibility to take the wait_lock. > > > > Today the wait_lock is irq safe, but the path to taking it in > > sched_setscheduler() is the same as the path to taking it from normal > > context. The wait_lock is taken with raw_spin_lock_irq() and released with > > raw_spin_unlock_irq() which will indiscriminately enable interrupts, > > which would be bad in interrupt context. > > > > The problem is that normalize_rt_tasks, which is called by triggering the > > sysrq nice-all-RT-tasks was changed to call __sched_setscheduler(), and this > > is done from interrupt context! > > > > Now __sched_setscheduler() takes a "pi" parameter that is used to know if > > the priority inheritance should be called or not. As the BUG_ON() only cares > > about calling the PI code, it should only bug if called from interrupt > > context with the "pi" parameter set to true. > > > > Link: http://lkml.kernel.org/r/[email protected] > > > > Reported-by: Laurent Dufour <[email protected]> > > Tested-by: Laurent Dufour <[email protected]> > > Fixes: dbc7f069b93a ("sched: Use replace normalize_task() with > > __sched_setscheduler()") > > Cc: Andrew Morton <[email protected]> > > Cc: Thomas Gleixner <[email protected]> > > Cc: Ingo Molnar <[email protected]> > > Cc: Peter Zijlstra <[email protected]> > > Cc: [email protected] > > Signed-off-by: Steven Rostedt (VMware) <[email protected]> > > Can this patch also be applied to the stable trees? The offending commit > was first introduced in 4.2.
What is the git commit id of this patch in Linus's tree? thanks, greg k-h
