Messages in this thread Patch in this message | | | Date | Wed, 19 Aug 2009 09:18:20 -0700 | From | Andrew Morton <> | Subject | Re: [BUG] lockup with the latest kernel |
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On Wed, 19 Aug 2009 11:49:25 -0400 (EDT) Steven Rostedt <rostedt@goodmis.org> wrote:
> Always happens where one CPU is sending an IPI and the other has the rq > spinlock. Seems to be that the IPI expects the other CPU to not have > interrupts disabled or something? > > Note, I've seen this on 2.6.30-rc6 as well (yes that's 2.6.30). But this > does not happen on 2.6.29. Unfortunately, 2.6.29 makes my NIC go kaputt > for some reason. > > I've enabled LOCKDEP and it just makes the bug trigger easier. > > Anyway, anyone have any ideas?
We'd need to see the backtrace on the target CPU.
It shouldn't be too hard - set that CPU's bit in arch/x86/kernel/apic/nmi.c:backtrace_mask and then clear it again when that CPU has responded.
Or even:
diff -puN arch/x86/kernel/apic/nmi.c~a arch/x86/kernel/apic/nmi.c --- a/arch/x86/kernel/apic/nmi.c~a +++ a/arch/x86/kernel/apic/nmi.c @@ -387,6 +387,8 @@ void touch_nmi_watchdog(void) } EXPORT_SYMBOL(touch_nmi_watchdog); +extern int wizzle; + notrace __kprobes int nmi_watchdog_tick(struct pt_regs *regs, unsigned reason) { @@ -415,7 +417,8 @@ nmi_watchdog_tick(struct pt_regs *regs, } /* We can be called before check_nmi_watchdog, hence NULL check. */ - if (backtrace_mask != NULL && cpumask_test_cpu(cpu, backtrace_mask)) { + if (cpu == wizzle || + (backtrace_mask != NULL && cpumask_test_cpu(cpu, backtrace_mask))) { static DEFINE_SPINLOCK(lock); /* Serialise the printks */ spin_lock(&lock); diff -puN arch/x86/kernel/smp.c~a arch/x86/kernel/smp.c --- a/arch/x86/kernel/smp.c~a +++ a/arch/x86/kernel/smp.c @@ -111,13 +111,17 @@ * it goes straight through and wastes no time serializing * anything. Worst case is that we lose a reschedule ... */ +int wizzle = -1; + static void native_smp_send_reschedule(int cpu) { if (unlikely(cpu_is_offline(cpu))) { WARN_ON(1); return; } + wizzle = cpu; apic->send_IPI_mask(cpumask_of(cpu), RESCHEDULE_VECTOR); + wizzle = -1; } void native_send_call_func_single_ipi(int cpu) _
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