On Wed, 18 Jun 2014 09:21:17 -0700 "Paul E. McKenney" <paul...@linux.vnet.ibm.com> wrote:
> On Wed, Jun 18, 2014 at 05:58:40AM -1000, Linus Torvalds wrote: > > On Jun 18, 2014 4:36 AM, "Paul E. McKenney" <paul...@linux.vnet.ibm.com> > > wrote: > > > > > > I could easily add an option to RCU to allow people to tell it not to > > > use NMIs to dump the stack. > > > > I don't think it should be an "option". > > > > We should stop using nmi as if it was something "normal". It isn't. Code > > running in nmi context should be special, and should be very very aware > > that it is special. That goes way beyond "don't use printk". We seem to > > have gone way way too far in using nmi context. > > > > So we should get *rid* of code in nmi context rather than then complain > > about printk being buggy. > > OK, unconditional non-use of NMIs is even easier. ;-) > > Something like the following. > I have found the RCU stalls extremely useful in debugging lockups. In case this doesn't work as well, I'm willing to write up something that could send NMIs to all CPUs that would write into the ftrace ring buffer and when finished, the calling CPU can dump it out. No printk from NMI context at all. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/