Messages in this thread |  | | Date | Wed, 04 Dec 2013 10:10:28 +0100 | From | Daniel Lezcano <> | Subject | Re: [PATCH] cpuidle: Check for dev before deregistering it. |
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On 12/03/2013 10:33 PM, Rafael J. Wysocki wrote: > On Tuesday, December 03, 2013 10:59:58 AM Konrad Rzeszutek Wilk wrote: >> If not, we could end up in the unfortunate situation where >> we dereference a NULL pointer b/c we have cpuidle disabled. >> >> This is the case when booting under Xen (which uses the >> ACPI P/C states but disables the CPU idle driver) - and can >> be easily reproduced when booting with cpuidle.off=1. >> >> BUG: unable to handle kernel NULL pointer dereference at (null) >> IP: [<ffffffff8156db4a>] cpuidle_unregister_device+0x2a/0x90 >> .. snip.. >> Call Trace: >> [<ffffffff813b15b4>] acpi_processor_power_exit+0x3c/0x5c >> [<ffffffff813af0a9>] acpi_processor_stop+0x61/0xb6 >> [<ffffffff814215bf>] __device_release_driver+0fffff81421653>] device_release_driver+0x23/0x30 >> [<ffffffff81420ed8>] bus_remove_device+0x108/0x180 >> [<ffffffff8141d9d9>] device_del+0x129/0x1c0 >> [<ffffffff813cb4b0>] ? unregister_xenbus_watch+0x1f0/0x1f0 >> [<ffffffff8141da8e>] device_unregister+0x1e/0x60 >> [<ffffffff814243e9>] unregister_cpu+0x39/0x60 >> [<ffffffff81019e03>] arch_unregister_cpu+0x23/0x30 >> [<ffffffff813c3c51>] handle_vcpu_hotplug_event+0xc1/0xe0 >> [<ffffffff813cb4f5>] xenwatch_thread+0x45/0x120 >> [<ffffffff810af010>] ? abort_exclusive_wait+0xb0/0xb0 >> [<ffffffff8108ec42>] kthread+0xd2/0xf0 >> [<ffffffff8108eb70>] ? kthread_create_on_node+0x180/0x180 >> [<ffffffff816ce17c>] ret_from_fork+0x7c/0xb0 >> [<ffffffff8108eb70>] ? kthread_create_on_node+0x180/0x180 >> >> This problem also appears in 3.12 and could be a candidate for backport. >> >> CC: "Rafael J. Wysocki" <rjw@rjwysocki.net> >> CC: Daniel Lezcano <daniel.lezcano@linaro.org> >> CC: linux-pm@vger.kernel.org >> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > > Applied, thanks! > >> --- >> drivers/cpuidle/cpuidle.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c >> index 2a991e4..a55e68f 100644 >> --- a/drivers/cpuidle/cpuidle.c >> +++ b/drivers/cpuidle/cpuidle.c >> @@ -400,7 +400,7 @@ EXPORT_SYMBOL_GPL(cpuidle_register_device); >> */ >> void cpuidle_unregister_device(struct cpuidle_device *dev) >> { >> - if (dev->registered == 0) >> + if (!dev || dev->registered == 0) >> return; >> >> cpuidle_pause_and_lock();
Oops, wait. Are we sure the problem is coming from cpuidle ?
The cpuidle_unregister_device is called with a NULL pointer, that shouldn't happen.
Konrad, you say that could be easily reproduced. How do you produce it ? Unplugging a cpu ?
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