4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxxxxxxx>
[ Upstream commit ad0a45fd9c14feebd000b6e84189d0edff265170 ]
If a given cpu is not in cpu_present and cpu hotplug
is disabled, arch can skip setting up the cpu_dev.
Arch cpuidle driver should pass correct cpu mask
for registration, but failing to do so by the driver
causes error to propagate and crash like this:
[ 30.076045] Unable to handle kernel paging request for data at address 0x00000048
[ 30.076100] Faulting instruction address: 0xc0000000007b2f30
cpu 0x4d: Vector: 300 (Data Access) at [c000003feb18b670]
pc: c0000000007b2f30: kobject_get+0x20/0x70
lr: c0000000007b3c94: kobject_add_internal+0x54/0x3f0
sp: c000003feb18b8f0
msr: 9000000000009033
dar: 48
dsisr: 40000000
current = 0xc000003fd2ed8300
paca = 0xc00000000fbab500 softe: 0 irq_happened: 0x01
pid = 1, comm = swapper/0
Linux version 4.11.0-rc2-svaidy+ (sv@sagarika) (gcc version 6.2.0
20161005 (Ubuntu 6.2.0-5ubuntu12) ) #10 SMP Sun Mar 19 00:08:09 IST 2017
enter ? for help
[c000003feb18b960] c0000000007b3c94 kobject_add_internal+0x54/0x3f0
[c000003feb18b9f0] c0000000007b43a4 kobject_init_and_add+0x64/0xa0
[c000003feb18ba70] c000000000e284f4 cpuidle_add_sysfs+0xb4/0x130
[c000003feb18baf0] c000000000e26038 cpuidle_register_device+0x118/0x1c0
[c000003feb18bb30] c000000000e26c48 cpuidle_register+0x78/0x120
[c000003feb18bbc0] c00000000168fd9c powernv_processor_idle_init+0x110/0x1c4
[c000003feb18bc40] c00000000000cff8 do_one_initcall+0x68/0x1d0
[c000003feb18bd00] c0000000016242f4 kernel_init_freeable+0x280/0x360
[c000003feb18bdc0] c00000000000d864 kernel_init+0x24/0x160
[c000003feb18be30] c00000000000b4e8 ret_from_kernel_thread+0x5c/0x74
Validating cpu_dev fixes the crash and reports correct error message like:
[ 30.163506] Failed to register cpuidle device for cpu136
[ 30.173329] Registration of powernv driver failed.
Signed-off-by: Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxxxxxxx>
[ rjw: Comment massage ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/cpuidle/sysfs.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
--- a/drivers/cpuidle/sysfs.c
+++ b/drivers/cpuidle/sysfs.c
@@ -613,6 +613,18 @@ int cpuidle_add_sysfs(struct cpuidle_dev
struct device *cpu_dev = get_cpu_device((unsigned long)dev->cpu);
int error;
+ /*
+ * Return if cpu_device is not setup for this CPU.
+ *
+ * This could happen if the arch did not set up cpu_device
+ * since this CPU is not in cpu_present mask and the
+ * driver did not send a correct CPU mask during registration.
+ * Without this check we would end up passing bogus
+ * value for &cpu_dev->kobj in kobject_init_and_add()
+ */
+ if (!cpu_dev)
+ return -ENODEV;
+
kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
if (!kdev)
return -ENOMEM;