Messages in this thread Patch in this message | | | From | Kamal Mostafa <> | Subject | [PATCH 3.8 89/91] cpuidle: Check for dev before deregistering it. | Date | Thu, 2 Jan 2014 09:05:04 -0800 |
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3.8.13.15 -stable review patch. If anyone has any objections, please let me know.
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From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
commit 813e8e3d6aaa0b511126cce15c16a931afffe768 upstream.
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.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> [ kamal: backport to 3.8 ] Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/cpuidle/cpuidle.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index e1f6860..7decd90 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -460,11 +460,13 @@ EXPORT_SYMBOL_GPL(cpuidle_register_device); */ void cpuidle_unregister_device(struct cpuidle_device *dev) { - struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); + struct cpuidle_driver *drv; - if (dev->registered == 0) + if (!dev || dev->registered == 0) return; + drv = cpuidle_get_cpu_driver(dev); + cpuidle_pause_and_lock(); cpuidle_disable_device(dev); -- 1.8.3.2
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