On Wed, 5 Nov 2014 00:05:12 +0100 (CET) Jiri Kosina <[email protected]> wrote:
> On Tue, 4 Nov 2014, Steven Rostedt wrote: > > > From: "Steven Rostedt (Red Hat)" <[email protected]> > > > > When trigger_all_cpu_backtrace() is called on x86, it will trigger an > > NMI on each CPU and call show_regs(). But this can lead to a hard lock > > up if the NMI comes in on another printk(). > > > > In order to avoid this, when the NMI triggers, it switches the printk > > routine for that CPU to call a NMI safe printk function that records the > > printk in a per_cpu seq_buf descriptor. After all NMIs have finished > > recording its data, the trace_seqs are printed in a safe context. Hmm, I need to update the change log to say seq_bufs instead of trace_seqs. > > > > Link: http://lkml.kernel.org/p/[email protected] > > > > Acked-by: Paul E. McKenney <[email protected]> > > Signed-off-by: Steven Rostedt <[email protected]> > > I've been running the whole machinery that used to trigger very quickly > the complete hardlock of the machine (*) for the whole evening/night, and > it's still running flawlessly. > > Plus, as I said previously, I agree with the whole idea (given the > general nastiness of the problem and given the fact this simply has to be > fixed without pointless delays). > > I.e FWIW > > Tested-by: Jiri Kosina <[email protected]> > Acked-by: Jiri Kosina <[email protected]> > > for the whole series. Thanks! I'll update the commits. -- Steve > > (*) heavy printk() workload (**) + sysrq-l in parallel > (**) iptables logging every incoming packet + flood ping from another > machine > > Thanks, > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
