This is a note to let you know that I've just added the patch titled
cpuidle: Check for dev before deregistering it.
to the 3.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cpuidle-check-for-dev-before-deregistering-it.patch
and it can be found in the queue-3.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 813e8e3d6aaa0b511126cce15c16a931afffe768 Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Tue, 3 Dec 2013 10:59:58 -0500
Subject: cpuidle: Check for dev before deregistering it.
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/cpuidle/cpuidle.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -448,7 +448,7 @@ EXPORT_SYMBOL_GPL(cpuidle_register_devic
*/
void cpuidle_unregister_device(struct cpuidle_device *dev)
{
- if (dev->registered == 0)
+ if (!dev || dev->registered == 0)
return;
cpuidle_pause_and_lock();
Patches currently in stable-queue which might be from konrad.wilk@xxxxxxxxxx are
queue-3.12/xen-gnttab-leave-lazy-mmu-mode-in-the-case-of-a-m2p-override-failure.patch
queue-3.12/cpuidle-check-for-dev-before-deregistering-it.patch
queue-3.12/irq-enable-all-irqs-unconditionally-in-irq_resume.patch
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