Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 5/7] x86: Enter rcu extended qs after idle notifier call | Date | Mon, 26 Sep 2011 12:19:10 +0200 |
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The idle notifier, called by enter_idle(), enters into rcu read side critical section but at that time we already switched into rcu dynticks idle mode. And it's illegal to use rcu_read_lock() in that state.
This results in rcu reporting its bad mood:
[ 1.275635] WARNING: at include/linux/rcupdate.h:194 __atomic_notifier_call_chain+0xd2/0x110() [ 1.275635] Hardware name: AMD690VM-FMH [ 1.275635] Modules linked in: [ 1.275635] Pid: 0, comm: swapper Not tainted 3.0.0-rc6+ #252 [ 1.275635] Call Trace: [ 1.275635] [<ffffffff81051c8a>] warn_slowpath_common+0x7a/0xb0 [ 1.275635] [<ffffffff81051cd5>] warn_slowpath_null+0x15/0x20 [ 1.275635] [<ffffffff817d6f22>] __atomic_notifier_call_chain+0xd2/0x110 [ 1.275635] [<ffffffff817d6f71>] atomic_notifier_call_chain+0x11/0x20 [ 1.275635] [<ffffffff810018a0>] enter_idle+0x20/0x30 [ 1.275635] [<ffffffff81001995>] cpu_idle+0xa5/0x110 [ 1.275635] [<ffffffff817a7465>] rest_init+0xe5/0x140 [ 1.275635] [<ffffffff817a73c8>] ? rest_init+0x48/0x140 [ 1.275635] [<ffffffff81cc5ca3>] start_kernel+0x3d1/0x3dc [ 1.275635] [<ffffffff81cc5321>] x86_64_start_reservations+0x131/0x135 [ 1.275635] [<ffffffff81cc5412>] x86_64_start_kernel+0xed/0xf4 [ 1.275635] ---[ end trace a22d306b065d4a66 ]---
Fix this by entering rcu extended quiescent state later, just before the CPU goes to sleep.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: H. Peter Anvin <hpa@zytor.com> --- arch/x86/kernel/process_64.c | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 19ca231..dee2e6c 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -120,7 +120,7 @@ void cpu_idle(void) /* endless idle loop with no priority at all */ while (1) { - tick_nohz_idle_enter(true); + tick_nohz_idle_enter(false); while (!need_resched()) { rmb(); @@ -136,7 +136,12 @@ void cpu_idle(void) enter_idle(); /* Don't trace irqs off for idle */ stop_critical_timings(); + + /* enter_idle() needs rcu for notifiers */ + rcu_enter_nohz(); pm_idle(); + rcu_exit_nohz(); + start_critical_timings(); /* In many cases the interrupt that ended idle -- 1.7.5.4
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