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. -- error compiling committee.c: too many arguments to function -- 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
