On Tue, Nov 06, 2012 at 04:08:15PM +0800, Mojiong Qiu wrote:
> exit_idle() should be called after irq_enter(), otherwise it throws:
That seems odd - wouldn't "smp_x86_platform_ipi"
also need the same treatment [edit: I was looking at 3.0 kernel code] ?
Ah, this is caused by
commit 98ad1cc14a5c4fd658f9d72c6ba5c86dfd3ce0d5
Author: Frederic Weisbecker <fweis...@gmail.com>
Date: Fri Oct 7 18:22:09 2011 +0200
x86: Call idle notifier after irq_enter()
and it missed the xen-case
which means that any kernel v3.3 and newer need this, but earlier do
not.
Thx. Will put in 3.7 tree.
>
> [ 2.513020] [ INFO: suspicious RCU usage. ]
> [ 2.513076] 3.6.5 #1 Not tainted
> [ 2.513128] -------------------------------
> [ 2.513183] include/linux/rcupdate.h:725 rcu_read_lock() used illegally
> while idle!
> [ 2.513271]
> [ 2.513271] other info that might help us debug this:
> [ 2.513271]
> [ 2.513388]
> [ 2.513388] RCU used illegally from idle CPU!
> [ 2.513388] rcu_scheduler_active = 1, debug_locks = 1
> [ 2.513511] RCU used illegally from extended quiescent state!
> [ 2.513572] 1 lock held by swapper/0/0:
> [ 2.513626] #0: (rcu_read_lock){......}, at: [<ffffffff810e9fe0>]
> __atomic_notifier_call_chain+0x0/0x140
> [ 2.513815]
> [ 2.513815] stack backtrace:
> [ 2.513897] Pid: 0, comm: swapper/0 Not tainted 3.6.5 #1
> [ 2.513954] Call Trace:
> [ 2.514005] <IRQ> [<ffffffff811259a2>] lockdep_rcu_suspicious+0xe2/0x130
> [ 2.514107] [<ffffffff810ea10c>] __atomic_notifier_call_chain+0x12c/0x140
> [ 2.514169] [<ffffffff810e9fe0>] ?
> atomic_notifier_chain_unregister+0x90/0x90
> [ 2.514258] [<ffffffff811216cd>] ? trace_hardirqs_off+0xd/0x10
> [ 2.514318] [<ffffffff810ea136>] atomic_notifier_call_chain+0x16/0x20
> [ 2.514381] [<ffffffff810777c3>] exit_idle+0x43/0x50
> [ 2.514441] [<ffffffff81568865>] xen_evtchn_do_upcall+0x25/0x50
> [ 2.514503] [<ffffffff81aa690e>] xen_do_hypervisor_callback+0x1e/0x30
> [ 2.514562] <EOI> [<ffffffff810013aa>] ? hypercall_page+0x3aa/0x1000
> [ 2.514662] [<ffffffff810013aa>] ? hypercall_page+0x3aa/0x1000
> [ 2.514722] [<ffffffff81061540>] ? xen_safe_halt+0x10/0x20
> [ 2.514782] [<ffffffff81075cfa>] ? default_idle+0xba/0x570
> [ 2.514841] [<ffffffff810778af>] ? cpu_idle+0xdf/0x140
> [ 2.514900] [<ffffffff81a4d881>] ? rest_init+0x135/0x144
> [ 2.514960] [<ffffffff81a4d74c>] ? csum_partial_copy_generic+0x16c/0x16c
> [ 2.515022] [<ffffffff82520c45>] ? start_kernel+0x3db/0x3e8
> [ 2.515081] [<ffffffff8252066a>] ? repair_env_string+0x5a/0x5a
> [ 2.515141] [<ffffffff82520356>] ? x86_64_start_reservations+0x131/0x135
> [ 2.515202] [<ffffffff82524aca>] ? xen_start_kernel+0x465/0x46
>
> Signed-off-by: Mojiong Qiu <mj...@tencent.com>
> Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
> Cc: Jeremy Fitzhardinge <jer...@goop.org>
> Cc: xen-de...@lists.xensource.com
> Cc: virtualization@lists.linux-foundation.org
> Cc: linux-ker...@vger.kernel.org
> Cc: sta...@kernel.org (at least to 3.0.y)
^^^- vger.kernel.org
You mean 3.3.x
> ---
> drivers/xen/events.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> index 912ac81..0be4df3 100644
> --- a/drivers/xen/events.c
> +++ b/drivers/xen/events.c
> @@ -1395,10 +1395,10 @@ void xen_evtchn_do_upcall(struct pt_regs *regs)
> {
> struct pt_regs *old_regs = set_irq_regs(regs);
>
> + irq_enter();
> #ifdef CONFIG_X86
> exit_idle();
> #endif
> - irq_enter();
>
> __xen_evtchn_do_upcall();
>
> --
> 1.6.3.2
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