exit_idle() should be called after irq_enter(), otherwise it throws:
[ 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 <mjqiu at tencent.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Cc: Jeremy Fitzhardinge <jeremy at goop.org>
Cc: xen-devel at lists.xensource.com
Cc: virtualization at lists.linux-foundation.org
Cc: linux-kernel at vger.kernel.org
Cc: stable at kernel.org (at least to 3.0.y)
---
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
Konrad Rzeszutek Wilk
2012-Nov-06 16:17 UTC
[PATCH] xen/events: xen/events: fix RCU warning
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 <fweisbec at 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 <mjqiu at tencent.com> > Cc: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com> > Cc: Jeremy Fitzhardinge <jeremy at goop.org> > Cc: xen-devel at lists.xensource.com > Cc: virtualization at lists.linux-foundation.org > Cc: linux-kernel at vger.kernel.org > Cc: stable at 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