Messages in this thread | | | Date | Tue, 25 Sep 2012 00:47:55 +0200 | From | Sasha Levin <> | Subject | Re: RCU idle CPU detection is broken in linux-next |
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Hi Frederic,
On 09/24/2012 11:29 PM, Frederic Weisbecker wrote: > Sasha, > > Can you please test the following branch: > > git://github.com/fweisbec/linux-dynticks.git rcu/idle-for-v3.7-take3 > > with CONFIG_RCU_USER_QS and CONFIG_RCU_USER_QS_FORCE enabled. > > I hope this fixes the warning. > The changes are: > > * add "x86: Unspaghettize do_general_protection()" > * updated "x86: Exception hooks for userspace RCU extended QS" to > handle some missed trap handlers. Especially do_general_protection() > because I can see the problem triggered there in Sasha's warnings. I > fixed more handlers in the way.
I've tested the branch above, and noticed two things:
- I had merge conflicts when pulling it on top of latest linux-next which I've resolved:
diff --cc arch/x86/kernel/traps.c index 1ba4850,cb20776..386b079 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@@ -644,8 -646,7 +647,9 @@@ EXPORT_SYMBOL_GPL(math_state_restore) dotraplinkage void __kprobes do_device_not_available(struct pt_regs *regs, long error_code) { + BUG_ON(use_eager_fpu()); + + exception_enter(regs); #ifdef CONFIG_MATH_EMULATION if (read_cr0() & X86_CR0_EM) { struct math_emu_info info = { };
- While I no longer see the warnings I've originally noticed, if I run with Paul's last debug patch I see the following warning:
[ 212.200137] WARNING: at arch/x86/kernel/process.c:392 cpu_idle+0x12a/0x1f0() [ 212.200141] Pid: 0, comm: swapper/3 Tainted: G W 3.6.0-rc6-next-20120924-sasha-00030-g71f256c #5 [ 212.200142] Call Trace: [ 212.200146] [<ffffffff810799da>] ? cpu_idle+0x12a/0x1f0 [ 212.200150] [<ffffffff811078b6>] warn_slowpath_common+0x86/0xb0 [ 212.200153] [<ffffffff811079a5>] warn_slowpath_null+0x15/0x20 [ 212.200156] [<ffffffff810799da>] cpu_idle+0x12a/0x1f0 [ 212.200160] [<ffffffff839a3ee8>] ? setup_APIC_timer+0xb2/0xb6
Which is triggered by: if (cpuidle_idle_call()) pm_idle();
rcu_idle_exit(); WARN_ON(rcu_is_cpu_idle()); <---- THIS start_critical_timings();
/* In many cases the interrupt that ended idle has already called exit_idle. But some idle loops can be woken up without interrupt. */ WARN_ON(rcu_is_cpu_idle()); __exit_idle(); WARN_ON(rcu_is_cpu_idle());
Thanks, Sasha
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