On Mon, 03 Sep 2012, Michael Wang wrote: > On 09/01/2012 07:02 AM, Henrique de Moraes Holschuh wrote: > > Just got one of these: > > > > kernel: INFO: rcu_bh detected stall on CPU 2 (t=0 jiffies) > > kernel: Pid: 0, comm: swapper/2 Not tainted 3.2.28+ #2 > > kernel: Call Trace: > > kernel: <IRQ> [<ffffffff810d1609>] __rcu_pending+0x159/0x400 > > kernel: [<ffffffff810d20bb>] rcu_check_callbacks+0x9b/0x120 > > kernel: [<ffffffff81089673>] update_process_times+0x43/0x80 > > kernel: [<ffffffff810a836f>] tick_sched_timer+0x5f/0xb0 > > kernel: [<ffffffff8109c097>] __run_hrtimer.isra.30+0x57/0x100 > > kernel: [<ffffffff8109c8f5>] hrtimer_interrupt+0xe5/0x220 > > kernel: [<ffffffff8104ce14>] smp_apic_timer_interrupt+0x64/0xa0 > > kernel: [<ffffffff8159b5cb>] apic_timer_interrupt+0x6b/0x70 > > kernel: <EOI> [<ffffffff81315645>] ? intel_idle+0xe5/0x140 > > kernel: [<ffffffff81315623>] ? intel_idle+0xc3/0x140 > > kernel: [<ffffffff814420ee>] cpuidle_idle_call+0x8e/0xf0 > > kernel: [<ffffffff81032425>] cpu_idle+0xa5/0x110 > > kernel: [<ffffffff8158a9ac>] start_secondary+0x1e5/0x1ec > > Hi, Henrique > > rsp->gp_start and rsp->jiffies_stall should already set before we start > check stall for this gp, but the INFO show that we have a current > jiffies which bigger then rsp->jiffies_stall but equal to rsp->gp_start, > really strange... > > Could you please have a try on the latest kernel and confirm whether > this issue still exist?
It is a production box, it is difficult to run a -rc kernel there. And the stalls are very rare, too. That's the only one I got, so at this point I cannot tell you whether something fixed the problem or not, just try to give you clues if a stall does happen. > BTW: > Is this stall info comes from a virtual machine? No, it runs on baremetal. The box has one Xeon X5550 processor, 4 cores, 8 threads, and it is allowed to go into C1, C3 and C6 (which it does very very often). It might be some sort of race related to SMIs? The worst-case SMM-induced delay on this box is quite high (I don't recall if that means 150ms or 150us), as measured by the Intel BITS[1]. [1] http://biosbits.org/ -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh -- 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/