On Thu, Apr 5, 2012 at 2:24 PM, Avi Kivity <avi@xxxxxxxxxx> wrote: > On 04/04/2012 11:12 PM, Sasha Levin wrote: >> Hi all, >> >> I've starting seeing soft lockups resulting from smp_call_function() >> calls. I've attached two different backtraces of this happening with >> different code paths. >> >> This is running inside a KVM guest with the trinity fuzzer, using >> today's linux-next kernel. >> >> [ 6540.134009] BUG: soft lockup - CPU#0 stuck for 22s! [kworker/u:1:38] >> [ 6540.134048] irq event stamp: 286811770 >> [ 6540.134048] hardirqs last enabled at (286811769): >> [<ffffffff82669e74>] restore_args+0x0/0x30 >> [ 6540.134048] hardirqs last disabled at (286811770): >> [<ffffffff8266b3ea>] apic_timer_interrupt+0x6a/0x80 >> [ 6540.134048] softirqs last enabled at (286811768): >> [<ffffffff810b746e>] __do_softirq+0x16e/0x190 >> [ 6540.134048] softirqs last disabled at (286811749): >> [<ffffffff8266bdec>] call_softirq+0x1c/0x30 >> [ 6540.134048] CPU 0 >> [ 6540.134048] Pid: 38, comm: kworker/u:1 Tainted: G W >> 3.4.0-rc1-next-20120404-sasha-dirty #72 >> [ 6540.134048] RIP: 0010:[<ffffffff8111f30e>] [<ffffffff8111f30e>] >> smp_call_function_many+0x27e/0x2a0 >> > > This cpu is waiting for some other cpu to process a function (likely > rps_trigger_softirq(), from the trace). Can you get a backtrace on all > cpus when this happens? > > It would be good to enhance smp_call_function_*() to do this > automatically when it happens - it's spinning there anyway, so it might > as well count the iterations and NMI the lagging cpu if it waits for too > long. What do you think about modifying the softlockup detector to NMI all CPUs if it's going to panic because it detected a lockup? -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
