Messages in this thread | | | Date | Tue, 18 Nov 2014 16:25:53 -0500 | From | Don Zickus <> | Subject | Re: frequent lockups in 3.18rc4 |
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On Tue, Nov 18, 2014 at 08:28:01PM +0100, Thomas Gleixner wrote: > On Tue, 18 Nov 2014, Linus Torvalds wrote: > > On Tue, Nov 18, 2014 at 6:52 AM, Dave Jones <davej@redhat.com> wrote: > > > > > > Here's the first hit. Curiously, one cpu is missing. > > > > That might be the CPU3 that isn't responding to IPIs due to some bug.. > > > > > NMI watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [trinity-c180:17837] > > > RIP: 0010:[<ffffffffa91a0db0>] [<ffffffffa91a0db0>] bad_range+0x0/0x90 > > > > Hmm. Something looping in the page allocator? Not waiting for a lock, > > but livelocked? I'm not seeing anything here that should trigger the > > NMI watchdog at all. > > > > Can the NMI watchdog get confused somehow? > > That's the soft lockup detector which runs from the timer interrupt > not from NMI. > > > So it does look like CPU3 is the problem, but sadly, CPU3 is > > apparently not listening, and doesn't even react to the NMI, much less > > As I said in the other mail. It gets the NMI and reacts on it. It's > just mangled into the CPU0 backtrace.
I was going to reply about both points too. :-) Though the mangling looks odd because we have spin_locks serializing the output for each cpu.
Another thing I wanted to ask DaveJ, did you recently turn on CONFIG_PREEMPT? That would explain why you are seeing the softlockups now. If you disable CONFIG_PREEMPT does the softlockups disappear.
Cheers, Don
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