Messages in this thread | | | Date | Fri, 23 Dec 2005 10:29:59 -0600 | From | "K.R. Foley" <> | Subject | Re: 2.6.15-rc5-rt4: BUG: swapper:0 task might have lost a preemption check! |
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Steven Rostedt wrote: > On Thu, 2005-12-22 at 21:14 -0600, K.R. Foley wrote: >> Lee Revell wrote: >>> Got this on boot. Same .config as the last one I sent you. >>> >>> VP_IDE: VIA vt8235 (rev 00) IDE UDMA133 controller on pci0000:00:11.1 >>> ide1: BM-DMA at 0xe008-0xe00f, BIOS settings: hdc:DMA, hdd:pio >>> Probing IDE interface ide1... >>> BUG: swapper:0 task might have lost a preemption check! >>> [<c010440c>] dump_stack+0x1c/0x20 (20) >>> [<c01166aa>] preempt_enable_no_resched+0x5a/0x60 (20) >>> [<c0100dd9>] cpu_idle+0x79/0xb0 (12) >>> [<c0100280>] _stext+0x40/0x50 (28) >>> [<c03078e6>] start_kernel+0x176/0x1d0 (20) >>> [<c0100199>] 0xc0100199 (1086889999) >>> --------------------------- >>> | preempt count: 00000000 ] >>> | 0-level deep critical section nesting: >>> ---------------------------------------- >>> >>> > > > OK, I just found an SMP bug, and here's the patch. Maybe this will help > you kr. I'm currently running x86_64 SMP with 2.6.15-rc5-rt4 with this > and my softirq-no-hrtimers patch I sent earlier. > > -- Steve > > Index: linux-2.6.15-rc5-rt4/kernel/workqueue.c > =================================================================== > --- linux-2.6.15-rc5-rt4.orig/kernel/workqueue.c 2005-12-23 10:23:25.000000000 -0500 > +++ linux-2.6.15-rc5-rt4/kernel/workqueue.c 2005-12-23 10:25:21.000000000 -0500 > @@ -370,10 +370,17 @@ > void set_workqueue_thread_prio(struct workqueue_struct *wq, int cpu, > int policy, int rt_priority, int nice) > { > - struct task_struct *p = wq->cpu_wq[cpu].thread; > + struct cpu_workqueue_struct *cwq; > + struct task_struct *p; > struct sched_param param = { .sched_priority = rt_priority }; > + unsigned long flags; > int ret; > > + cwq = per_cpu_ptr(wq->cpu_wq, cpu); > + spin_lock_irqsave(&cwq->lock, flags); > + p = cwq->thread; > + spin_unlock_irqrestore(&cwq->lock, flags); > + > set_user_nice(p, nice); > ret = sys_sched_setscheduler(p->pid, policy, ¶m); > if (ret) > > >
OK. The BUG still exists (output below) but it does boot now with the above patch applied (THANKS Steven!), which would seem to imply the two weren't related. ARGH! :)
Dec 23 10:16:27 porky kernel: Event source lapic installed with caps set: 06 Dec 23 10:16:27 porky kernel: BUG: swapper:0 task might have lost a preemption check! Dec 23 10:16:27 porky kernel: Brought up 2 CPUs Dec 23 10:16:27 porky kernel: checking if image is initramfs... it is Dec 23 10:16:27 porky kernel: [<c010424e>] dump_stack+0x1e/0x20 (20) Dec 23 10:16:27 porky kernel: [<c011c9cf>] preempt_enable_no_resched+0x5f/0x70 (20) Dec 23 10:16:27 porky kernel: [<c0100ff2>] cpu_idle+0xb2/0x100 (40) Dec 23 10:16:27 porky kernel: [<c0111446>] start_secondary+0x296/0x340<6>Freeing initrd memory: 452k freed
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