mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-30 23:16:37 +07:00
a263898f62
make randconfig bootup testing found that the cpufreq code
crashes on bootup, if the powernow-k8 driver is enabled and
if maxcpus=1 passed on the boot line to a !CONFIG_HOTPLUG_CPU
kernel.
First lockdep found out that there's an inconsistent unlock
sequence:
=====================================
[ BUG: bad unlock balance detected! ]
-------------------------------------
swapper/1 is trying to release lock (&per_cpu(cpu_policy_rwsem, cpu)) at:
[<ffffffff806ffd8e>] unlock_policy_rwsem_write+0x3c/0x42
but there are no more locks to release!
Call Trace:
[<ffffffff806ffd8e>] unlock_policy_rwsem_write+0x3c/0x42
[<ffffffff80251c29>] print_unlock_inbalance_bug+0x104/0x12c
[<ffffffff80252f3a>] mark_held_locks+0x56/0x94
[<ffffffff806ffd8e>] unlock_policy_rwsem_write+0x3c/0x42
[<ffffffff807008b6>] cpufreq_add_dev+0x2a8/0x5c4
...
then shortly afterwards the cpufreq code crashed on an assert:
------------[ cut here ]------------
kernel BUG at drivers/cpufreq/cpufreq.c:1068!
invalid opcode: 0000 [1] SMP
[...]
Call Trace:
[<ffffffff805145d6>] sysdev_driver_unregister+0x5b/0x91
[<ffffffff806ff520>] cpufreq_register_driver+0x15d/0x1a2
[<ffffffff80cc0596>] powernowk8_init+0x86/0x94
[...]
---[ end trace 1e9219be2b4431de ]---
the bug was caused by maxcpus=1 bootup, which brought up the
secondary core as !cpu_online() but !cpu_is_offline() either,
which on on !CONFIG_HOTPLUG_CPU is always 0 (include/linux/cpu.h):
/* CPUs don't go offline once they're online w/o CONFIG_HOTPLUG_CPU */
static inline int cpu_is_offline(int cpu) { return 0; }
but the cpufreq code uses cpu_online() and cpu_is_offline() in
a mixed way - the low-level drivers use cpu_online(), while
the cpufreq core uses cpu_is_offline(). This opened up the
possibility to add the non-initialized sysdev device of the
secondary core:
cpufreq-core: trying to register driver powernow-k8
cpufreq-core: adding CPU 0
powernow-k8: BIOS error - no PSB or ACPI _PSS objects
cpufreq-core: initialization failed
cpufreq-core: adding CPU 1
cpufreq-core: initialization failed
which then blew up. The fix is to make cpu_is_offline() always
the negation of cpu_online(). With that fix applied the kernel
boots up fine without crashing:
Calling initcall 0xffffffff80cc0510: powernowk8_init+0x0/0x94()
powernow-k8: Found 1 AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ processors (1 cpu cores) (version 2.20.00)
powernow-k8: BIOS error - no PSB or ACPI _PSS objects
initcall 0xffffffff80cc0510: powernowk8_init+0x0/0x94() returned -19.
initcall 0xffffffff80cc0510 ran for 19 msecs: powernowk8_init+0x0/0x94()
Calling initcall 0xffffffff80cc328f: init_lapic_nmi_sysfs+0x0/0x39()
We could fix this by making CPU enumeration aware of max_cpus, but that
would be more fragile IMO, and the cpu_online(cpu) != cpu_is_offline(cpu)
possibility was quite confusing and a continuous source of bugs too.
Most distributions have kernels with CPU hotplug enabled, so this bug
remained hidden for a long time.
Bug forensics:
The broken cpu_is_offline() API variant was introduced via:
commit a59d2e4e6977e7b94e003c96a41f07e96cddc340
Author: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon Mar 8 06:06:03 2004 -0800
[PATCH] minor cleanups for hotplug CPUs
( this predates linux-2.6.git, this commit is available from Thomas's
historic git tree. )
Then 1.5 years later the cpufreq code made use of it:
commit c32b6b8e52
Author: Ashok Raj <ashok.raj@intel.com>
Date: Sun Oct 30 14:59:54 2005 -0800
[PATCH] create and destroy cpufreq sysfs entries based on cpu notifiers
+ if (cpu_is_offline(cpu))
+ return 0;
which is a correct use of the subtly broken new API. v2.6.15 then
shipped with this bug included.
then it took two more years for random-kernel qa to hit it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
139 lines
3.8 KiB
C
139 lines
3.8 KiB
C
/*
|
|
* include/linux/cpu.h - generic cpu definition
|
|
*
|
|
* This is mainly for topological representation. We define the
|
|
* basic 'struct cpu' here, which can be embedded in per-arch
|
|
* definitions of processors.
|
|
*
|
|
* Basic handling of the devices is done in drivers/base/cpu.c
|
|
* and system devices are handled in drivers/base/sys.c.
|
|
*
|
|
* CPUs are exported via sysfs in the class/cpu/devices/
|
|
* directory.
|
|
*
|
|
* Per-cpu interfaces can be implemented using a struct device_interface.
|
|
* See the following for how to do this:
|
|
* - drivers/base/intf.c
|
|
* - Documentation/driver-model/interface.txt
|
|
*/
|
|
#ifndef _LINUX_CPU_H_
|
|
#define _LINUX_CPU_H_
|
|
|
|
#include <linux/sysdev.h>
|
|
#include <linux/node.h>
|
|
#include <linux/compiler.h>
|
|
#include <linux/cpumask.h>
|
|
#include <asm/semaphore.h>
|
|
#include <linux/mutex.h>
|
|
|
|
struct cpu {
|
|
int node_id; /* The node which contains the CPU */
|
|
int hotpluggable; /* creates sysfs control file if hotpluggable */
|
|
struct sys_device sysdev;
|
|
};
|
|
|
|
extern int register_cpu(struct cpu *cpu, int num);
|
|
extern struct sys_device *get_cpu_sysdev(unsigned cpu);
|
|
|
|
extern int cpu_add_sysdev_attr(struct sysdev_attribute *attr);
|
|
extern void cpu_remove_sysdev_attr(struct sysdev_attribute *attr);
|
|
|
|
extern int cpu_add_sysdev_attr_group(struct attribute_group *attrs);
|
|
extern void cpu_remove_sysdev_attr_group(struct attribute_group *attrs);
|
|
|
|
extern int sched_create_sysfs_power_savings_entries(struct sysdev_class *cls);
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
extern void unregister_cpu(struct cpu *cpu);
|
|
#endif
|
|
struct notifier_block;
|
|
|
|
#ifdef CONFIG_SMP
|
|
/* Need to know about CPUs going up/down? */
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
extern int register_cpu_notifier(struct notifier_block *nb);
|
|
extern void unregister_cpu_notifier(struct notifier_block *nb);
|
|
#else
|
|
|
|
#ifndef MODULE
|
|
extern int register_cpu_notifier(struct notifier_block *nb);
|
|
#else
|
|
static inline int register_cpu_notifier(struct notifier_block *nb)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
static inline void unregister_cpu_notifier(struct notifier_block *nb)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
int cpu_up(unsigned int cpu);
|
|
|
|
#else
|
|
|
|
static inline int register_cpu_notifier(struct notifier_block *nb)
|
|
{
|
|
return 0;
|
|
}
|
|
static inline void unregister_cpu_notifier(struct notifier_block *nb)
|
|
{
|
|
}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
extern struct sysdev_class cpu_sysdev_class;
|
|
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
/* Stop CPUs going up and down. */
|
|
|
|
static inline void cpuhotplug_mutex_lock(struct mutex *cpu_hp_mutex)
|
|
{
|
|
mutex_lock(cpu_hp_mutex);
|
|
}
|
|
|
|
static inline void cpuhotplug_mutex_unlock(struct mutex *cpu_hp_mutex)
|
|
{
|
|
mutex_unlock(cpu_hp_mutex);
|
|
}
|
|
|
|
extern void lock_cpu_hotplug(void);
|
|
extern void unlock_cpu_hotplug(void);
|
|
#define hotcpu_notifier(fn, pri) { \
|
|
static struct notifier_block fn##_nb = \
|
|
{ .notifier_call = fn, .priority = pri }; \
|
|
register_cpu_notifier(&fn##_nb); \
|
|
}
|
|
#define register_hotcpu_notifier(nb) register_cpu_notifier(nb)
|
|
#define unregister_hotcpu_notifier(nb) unregister_cpu_notifier(nb)
|
|
int cpu_down(unsigned int cpu);
|
|
|
|
#else /* CONFIG_HOTPLUG_CPU */
|
|
|
|
static inline void cpuhotplug_mutex_lock(struct mutex *cpu_hp_mutex)
|
|
{ }
|
|
static inline void cpuhotplug_mutex_unlock(struct mutex *cpu_hp_mutex)
|
|
{ }
|
|
|
|
#define lock_cpu_hotplug() do { } while (0)
|
|
#define unlock_cpu_hotplug() do { } while (0)
|
|
#define hotcpu_notifier(fn, pri) do { (void)(fn); } while (0)
|
|
/* These aren't inline functions due to a GCC bug. */
|
|
#define register_hotcpu_notifier(nb) ({ (void)(nb); 0; })
|
|
#define unregister_hotcpu_notifier(nb) ({ (void)(nb); })
|
|
#endif /* CONFIG_HOTPLUG_CPU */
|
|
|
|
#ifdef CONFIG_PM_SLEEP_SMP
|
|
extern int suspend_cpu_hotplug;
|
|
|
|
extern int disable_nonboot_cpus(void);
|
|
extern void enable_nonboot_cpus(void);
|
|
#else /* !CONFIG_PM_SLEEP_SMP */
|
|
#define suspend_cpu_hotplug 0
|
|
|
|
static inline int disable_nonboot_cpus(void) { return 0; }
|
|
static inline void enable_nonboot_cpus(void) {}
|
|
#endif /* !CONFIG_PM_SLEEP_SMP */
|
|
|
|
#endif /* _LINUX_CPU_H_ */
|