2020-09-08 06:31:25

by Zhang, Qiang

[permalink] [raw]
Subject: [PATCH v3] debugobjects: install CPU hotplug callback

From: Zqiang <[email protected]>

Due to CPU hotplug, it may never be online after it's offline,
some objects in percpu pool is never free. in order to avoid
this happening, install CPU hotplug callback, call this callback
func to free objects in percpu pool when CPU going offline.

Signed-off-by: Zqiang <[email protected]>
---
v1->v2:
Modify submission information.

v2->v3:
In CPU hotplug callback func, add clear percpu pool "obj_free" operation.
capitalize 'CPU', and use shorter preprocessor sequence.

include/linux/cpuhotplug.h | 1 +
lib/debugobjects.c | 24 ++++++++++++++++++++++++
2 files changed, 25 insertions(+)

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 3215023d4852..0c39d57e5342 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -36,6 +36,7 @@ enum cpuhp_state {
CPUHP_X86_MCE_DEAD,
CPUHP_VIRT_NET_DEAD,
CPUHP_SLUB_DEAD,
+ CPUHP_DEBUG_OBJ_DEAD,
CPUHP_MM_WRITEBACK_DEAD,
CPUHP_MM_VMSTAT_DEAD,
CPUHP_SOFTIRQ_DEAD,
diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index fe4557955d97..bb69a02c3e7b 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -19,6 +19,7 @@
#include <linux/slab.h>
#include <linux/hash.h>
#include <linux/kmemleak.h>
+#include <linux/cpu.h>

#define ODEBUG_HASH_BITS 14
#define ODEBUG_HASH_SIZE (1 << ODEBUG_HASH_BITS)
@@ -433,6 +434,24 @@ static void free_object(struct debug_obj *obj)
}
}

+#ifdef CONFIG_HOTPLUG_CPU
+static int object_cpu_offline(unsigned int cpu)
+{
+ struct debug_percpu_free *percpu_pool;
+ struct hlist_node *tmp;
+ struct debug_obj *obj;
+
+ percpu_pool = per_cpu_ptr(&percpu_obj_pool, cpu);
+ hlist_for_each_entry_safe(obj, tmp, &percpu_pool->free_objs, node) {
+ hlist_del(&obj->node);
+ kmem_cache_free(obj_cache, obj);
+ }
+ percpu_pool->obj_free = 0;
+
+ return 0;
+}
+#endif
+
/*
* We run out of memory. That means we probably have tons of objects
* allocated.
@@ -1367,6 +1386,11 @@ void __init debug_objects_mem_init(void)
} else
debug_objects_selftest();

+#ifdef CONFIG_HOTPLUG_CPU
+ cpuhp_setup_state_nocalls(CPUHP_DEBUG_OBJ_DEAD, "object:offline", NULL,
+ object_cpu_offline);
+#endif
+
/*
* Increase the thresholds for allocating and freeing objects
* according to the number of possible CPUs available in the system.
--
2.17.1


2020-09-08 18:27:18

by Waiman Long

[permalink] [raw]
Subject: Re: [PATCH v3] debugobjects: install CPU hotplug callback

On 9/8/20 2:27 AM, [email protected] wrote:
> From: Zqiang <[email protected]>
>
> Due to CPU hotplug, it may never be online after it's offline,
> some objects in percpu pool is never free. in order to avoid
> this happening, install CPU hotplug callback, call this callback
> func to free objects in percpu pool when CPU going offline.
>
> Signed-off-by: Zqiang <[email protected]>
> ---
> v1->v2:
> Modify submission information.
>
> v2->v3:
> In CPU hotplug callback func, add clear percpu pool "obj_free" operation.
> capitalize 'CPU', and use shorter preprocessor sequence.
>
> include/linux/cpuhotplug.h | 1 +
> lib/debugobjects.c | 24 ++++++++++++++++++++++++
> 2 files changed, 25 insertions(+)
>
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index 3215023d4852..0c39d57e5342 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -36,6 +36,7 @@ enum cpuhp_state {
> CPUHP_X86_MCE_DEAD,
> CPUHP_VIRT_NET_DEAD,
> CPUHP_SLUB_DEAD,
> + CPUHP_DEBUG_OBJ_DEAD,
> CPUHP_MM_WRITEBACK_DEAD,
> CPUHP_MM_VMSTAT_DEAD,
> CPUHP_SOFTIRQ_DEAD,
> diff --git a/lib/debugobjects.c b/lib/debugobjects.c
> index fe4557955d97..bb69a02c3e7b 100644
> --- a/lib/debugobjects.c
> +++ b/lib/debugobjects.c
> @@ -19,6 +19,7 @@
> #include <linux/slab.h>
> #include <linux/hash.h>
> #include <linux/kmemleak.h>
> +#include <linux/cpu.h>
>
> #define ODEBUG_HASH_BITS 14
> #define ODEBUG_HASH_SIZE (1 << ODEBUG_HASH_BITS)
> @@ -433,6 +434,24 @@ static void free_object(struct debug_obj *obj)
> }
> }
>
> +#ifdef CONFIG_HOTPLUG_CPU
> +static int object_cpu_offline(unsigned int cpu)
> +{
> + struct debug_percpu_free *percpu_pool;
> + struct hlist_node *tmp;
> + struct debug_obj *obj;
> +
> + percpu_pool = per_cpu_ptr(&percpu_obj_pool, cpu);
> + hlist_for_each_entry_safe(obj, tmp, &percpu_pool->free_objs, node) {
> + hlist_del(&obj->node);
> + kmem_cache_free(obj_cache, obj);
> + }
> + percpu_pool->obj_free = 0;

For pointer, it is better to use NULL for clarity.

Cheers,
Longman

> +
> + return 0;
> +}
> +#endif
> +
> /*
> * We run out of memory. That means we probably have tons of objects
> * allocated.
> @@ -1367,6 +1386,11 @@ void __init debug_objects_mem_init(void)
> } else
> debug_objects_selftest();
>
> +#ifdef CONFIG_HOTPLUG_CPU
> + cpuhp_setup_state_nocalls(CPUHP_DEBUG_OBJ_DEAD, "object:offline", NULL,
> + object_cpu_offline);
> +#endif
> +
> /*
> * Increase the thresholds for allocating and freeing objects
> * according to the number of possible CPUs available in the system.


2020-09-10 02:06:17

by Zhang, Qiang

[permalink] [raw]
Subject: 回复: [PATCH v3] debugobjects: install CPU ho tplug callback



________________________________________
??????: Waiman Long <[email protected]>
????ʱ??: 2020??9??9?? 2:23
?ռ???: Zhang, Qiang; [email protected]; [email protected]; [email protected]
????: [email protected]
????: Re: [PATCH v3] debugobjects: install CPU hotplug callback

On 9/8/20 2:27 AM, [email protected] wrote:
> From: Zqiang <[email protected]>
>
> Due to CPU hotplug, it may never be online after it's offline,
> some objects in percpu pool is never free. in order to avoid
> this happening, install CPU hotplug callback, call this callback
> func to free objects in percpu pool when CPU going offline.
>
> Signed-off-by: Zqiang <[email protected]>
> ---
> v1->v2:
> Modify submission information.
>
> v2->v3:
> In CPU hotplug callback func, add clear percpu pool "obj_free" operation.
> capitalize 'CPU', and use shorter preprocessor sequence.
>
> include/linux/cpuhotplug.h | 1 +
> lib/debugobjects.c | 24 ++++++++++++++++++++++++
> 2 files changed, 25 insertions(+)
>
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index 3215023d4852..0c39d57e5342 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -36,6 +36,7 @@ enum cpuhp_state {
> CPUHP_X86_MCE_DEAD,
> CPUHP_VIRT_NET_DEAD,
> CPUHP_SLUB_DEAD,
> + CPUHP_DEBUG_OBJ_DEAD,
> CPUHP_MM_WRITEBACK_DEAD,
> CPUHP_MM_VMSTAT_DEAD,
> CPUHP_SOFTIRQ_DEAD,
> diff --git a/lib/debugobjects.c b/lib/debugobjects.c
> index fe4557955d97..bb69a02c3e7b 100644
> --- a/lib/debugobjects.c
> +++ b/lib/debugobjects.c
> @@ -19,6 +19,7 @@
> #include <linux/slab.h>
> #include <linux/hash.h>
> #include <linux/kmemleak.h>
> +#include <linux/cpu.h>
>
> #define ODEBUG_HASH_BITS 14
> #define ODEBUG_HASH_SIZE (1 << ODEBUG_HASH_BITS)
> @@ -433,6 +434,24 @@ static void free_object(struct debug_obj *obj)
> }
> }
>
> +#ifdef CONFIG_HOTPLUG_CPU
> +static int object_cpu_offline(unsigned int cpu)
> +{
> + struct debug_percpu_free *percpu_pool;
> + struct hlist_node *tmp;
> + struct debug_obj *obj;
> +
> + percpu_pool = per_cpu_ptr(&percpu_obj_pool, cpu);
> + hlist_for_each_entry_safe(obj, tmp, &percpu_pool->free_objs, node) {
> + hlist_del(&obj->node);
> + kmem_cache_free(obj_cache, obj);
> + }
> + percpu_pool->obj_free = 0;

>>For pointer, it is better to use NULL for clarity.

>>Cheers,
>>Longman

Do you mean "->obj_free" variable ? this represents the number of free objects in percpu_pool .

> +
> + return 0;
> +}
> +#endif
> +
> /*
> * We run out of memory. That means we probably have tons of objects
> * allocated.
> @@ -1367,6 +1386,11 @@ void __init debug_objects_mem_init(void)
> } else
> debug_objects_selftest();
>
> +#ifdef CONFIG_HOTPLUG_CPU
> + cpuhp_setup_state_nocalls(CPUHP_DEBUG_OBJ_DEAD, "object:offline", NULL,
> + object_cpu_offline);
> +#endif
> +
> /*
> * Increase the thresholds for allocating and freeing objects
> * according to the number of possible CPUs available in the system.


2020-09-10 02:52:55

by Waiman Long

[permalink] [raw]
Subject: Re: 回复: [PATCH v3] debugobjects: insta ll CPU hotplug callback

On 9/9/20 9:48 PM, Zhang, Qiang wrote:
>
> ________________________________________
> ??????: Waiman Long <[email protected]>
> ????ʱ??: 2020??9??9?? 2:23
> ?ռ???: Zhang, Qiang; [email protected]; [email protected]; [email protected]
> ????: [email protected]
> ????: Re: [PATCH v3] debugobjects: install CPU hotplug callback
>
> On 9/8/20 2:27 AM, [email protected] wrote:
>> From: Zqiang <[email protected]>
>>
>> Due to CPU hotplug, it may never be online after it's offline,
>> some objects in percpu pool is never free. in order to avoid
>> this happening, install CPU hotplug callback, call this callback
>> func to free objects in percpu pool when CPU going offline.
>>
>> Signed-off-by: Zqiang <[email protected]>
>> ---
>> v1->v2:
>> Modify submission information.
>>
>> v2->v3:
>> In CPU hotplug callback func, add clear percpu pool "obj_free" operation.
>> capitalize 'CPU', and use shorter preprocessor sequence.
>>
>> include/linux/cpuhotplug.h | 1 +
>> lib/debugobjects.c | 24 ++++++++++++++++++++++++
>> 2 files changed, 25 insertions(+)
>>
>> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
>> index 3215023d4852..0c39d57e5342 100644
>> --- a/include/linux/cpuhotplug.h
>> +++ b/include/linux/cpuhotplug.h
>> @@ -36,6 +36,7 @@ enum cpuhp_state {
>> CPUHP_X86_MCE_DEAD,
>> CPUHP_VIRT_NET_DEAD,
>> CPUHP_SLUB_DEAD,
>> + CPUHP_DEBUG_OBJ_DEAD,
>> CPUHP_MM_WRITEBACK_DEAD,
>> CPUHP_MM_VMSTAT_DEAD,
>> CPUHP_SOFTIRQ_DEAD,
>> diff --git a/lib/debugobjects.c b/lib/debugobjects.c
>> index fe4557955d97..bb69a02c3e7b 100644
>> --- a/lib/debugobjects.c
>> +++ b/lib/debugobjects.c
>> @@ -19,6 +19,7 @@
>> #include <linux/slab.h>
>> #include <linux/hash.h>
>> #include <linux/kmemleak.h>
>> +#include <linux/cpu.h>
>>
>> #define ODEBUG_HASH_BITS 14
>> #define ODEBUG_HASH_SIZE (1 << ODEBUG_HASH_BITS)
>> @@ -433,6 +434,24 @@ static void free_object(struct debug_obj *obj)
>> }
>> }
>>
>> +#ifdef CONFIG_HOTPLUG_CPU
>> +static int object_cpu_offline(unsigned int cpu)
>> +{
>> + struct debug_percpu_free *percpu_pool;
>> + struct hlist_node *tmp;
>> + struct debug_obj *obj;
>> +
>> + percpu_pool = per_cpu_ptr(&percpu_obj_pool, cpu);
>> + hlist_for_each_entry_safe(obj, tmp, &percpu_pool->free_objs, node) {
>> + hlist_del(&obj->node);
>> + kmem_cache_free(obj_cache, obj);
>> + }
>> + percpu_pool->obj_free = 0;
>>> For pointer, it is better to use NULL for clarity.
>>> Cheers,
>>> Longman
> Do you mean "->obj_free" variable ? this represents the number of free objects in percpu_pool .
>
You are right. I got confused. Sorry for the noise.

Cheers,
Longman

2020-09-16 06:01:25

by Zhang, Qiang

[permalink] [raw]
Subject: 回复: 回复: [PATCH v3] debugobjects: install CPU hotplug callback



________________________________________
??????: Waiman Long <[email protected]>
????ʱ??: 2020??9??10?? 10:50
?ռ???: Zhang, Qiang; [email protected]; [email protected]; [email protected]
????: [email protected]
????: Re: ?ظ?: [PATCH v3] debugobjects: install CPU hotplug callback

On 9/9/20 9:48 PM, Zhang, Qiang wrote:
>
> ________________________________________
> ??????: Waiman Long <[email protected]>
> ????ʱ??: 2020??9??9?? 2:23
> ?ռ???: Zhang, Qiang; [email protected]; [email protected]; [email protected]
> ????: [email protected]
> ????: Re: [PATCH v3] debugobjects: install CPU hotplug callback
>
> On 9/8/20 2:27 AM, [email protected] wrote:
>> From: Zqiang <[email protected]>
>>
>> Due to CPU hotplug, it may never be online after it's offline,
>> some objects in percpu pool is never free. in order to avoid
>> this happening, install CPU hotplug callback, call this callback
>> func to free objects in percpu pool when CPU going offline.
>>
>> Signed-off-by: Zqiang <[email protected]>
>> ---
>> v1->v2:
>> Modify submission information.
>>
>> v2->v3:
>> In CPU hotplug callback func, add clear percpu pool "obj_free" operation.
>> capitalize 'CPU', and use shorter preprocessor sequence.
>>
>> include/linux/cpuhotplug.h | 1 +
>> lib/debugobjects.c | 24 ++++++++++++++++++++++++
>> 2 files changed, 25 insertions(+)
>>
>> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
>> index 3215023d4852..0c39d57e5342 100644
>> --- a/include/linux/cpuhotplug.h
>> +++ b/include/linux/cpuhotplug.h
>> @@ -36,6 +36,7 @@ enum cpuhp_state {
>> CPUHP_X86_MCE_DEAD,
>> CPUHP_VIRT_NET_DEAD,
>> CPUHP_SLUB_DEAD,
>> + CPUHP_DEBUG_OBJ_DEAD,
>> CPUHP_MM_WRITEBACK_DEAD,
>> CPUHP_MM_VMSTAT_DEAD,
>> CPUHP_SOFTIRQ_DEAD,
>> diff --git a/lib/debugobjects.c b/lib/debugobjects.c
>> index fe4557955d97..bb69a02c3e7b 100644
>> --- a/lib/debugobjects.c
>> +++ b/lib/debugobjects.c
>> @@ -19,6 +19,7 @@
>> #include <linux/slab.h>
>> #include <linux/hash.h>
>> #include <linux/kmemleak.h>
>> +#include <linux/cpu.h>
>>
>> #define ODEBUG_HASH_BITS 14
>> #define ODEBUG_HASH_SIZE (1 << ODEBUG_HASH_BITS)
>> @@ -433,6 +434,24 @@ static void free_object(struct debug_obj *obj)
>> }
>> }
>>
>> +#ifdef CONFIG_HOTPLUG_CPU
>> +static int object_cpu_offline(unsigned int cpu)
>> +{
>> + struct debug_percpu_free *percpu_pool;
>> + struct hlist_node *tmp;
>> + struct debug_obj *obj;
>> +
>> + percpu_pool = per_cpu_ptr(&percpu_obj_pool, cpu);
>> + hlist_for_each_entry_safe(obj, tmp, &percpu_pool->free_objs, node) {
>> + hlist_del(&obj->node);
>> + kmem_cache_free(obj_cache, obj);
>> + }
>> + percpu_pool->obj_free = 0;
>>> For pointer, it is better to use NULL for clarity.
>>> Cheers,
>>> Longman
> Do you mean "->obj_free" variable ? this represents the number of free objects in percpu_pool .
>
>>You are right. I got confused. Sorry for the noise.

>>Cheers,
>>Longman

Hello tglx, mingo

Is this patch acceptable?

Thanks

Qiang

Subject: [tip: core/debugobjects] debugobjects: Free per CPU pool after CPU unplug

The following commit has been merged into the core/debugobjects branch of tip:

Commit-ID: 88451f2cd3cec2abc30debdf129422d2699d1eba
Gitweb: https://git.kernel.org/tip/88451f2cd3cec2abc30debdf129422d2699d1eba
Author: Zqiang <[email protected]>
AuthorDate: Tue, 08 Sep 2020 14:27:09 +08:00
Committer: Thomas Gleixner <[email protected]>
CommitterDate: Thu, 01 Oct 2020 16:13:54 +02:00

debugobjects: Free per CPU pool after CPU unplug

If a CPU is offlined the debug objects per CPU pool is not cleaned up. If
the CPU is never onlined again then the objects in the pool are wasted.

Add a CPU hotplug callback which is invoked after the CPU is dead to free
the pool.

[ tglx: Massaged changelog and added comment about remote access safety ]

Signed-off-by: Zqiang <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Waiman Long <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

---
include/linux/cpuhotplug.h | 1 +
lib/debugobjects.c | 25 +++++++++++++++++++++++++
2 files changed, 26 insertions(+)

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index bf9181c..6f524bb 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -36,6 +36,7 @@ enum cpuhp_state {
CPUHP_X86_MCE_DEAD,
CPUHP_VIRT_NET_DEAD,
CPUHP_SLUB_DEAD,
+ CPUHP_DEBUG_OBJ_DEAD,
CPUHP_MM_WRITEBACK_DEAD,
CPUHP_MM_VMSTAT_DEAD,
CPUHP_SOFTIRQ_DEAD,
diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index e2a3171..9e14ae0 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -19,6 +19,7 @@
#include <linux/slab.h>
#include <linux/hash.h>
#include <linux/kmemleak.h>
+#include <linux/cpu.h>

#define ODEBUG_HASH_BITS 14
#define ODEBUG_HASH_SIZE (1 << ODEBUG_HASH_BITS)
@@ -433,6 +434,25 @@ static void free_object(struct debug_obj *obj)
}
}

+#ifdef CONFIG_HOTPLUG_CPU
+static int object_cpu_offline(unsigned int cpu)
+{
+ struct debug_percpu_free *percpu_pool;
+ struct hlist_node *tmp;
+ struct debug_obj *obj;
+
+ /* Remote access is safe as the CPU is dead already */
+ percpu_pool = per_cpu_ptr(&percpu_obj_pool, cpu);
+ hlist_for_each_entry_safe(obj, tmp, &percpu_pool->free_objs, node) {
+ hlist_del(&obj->node);
+ kmem_cache_free(obj_cache, obj);
+ }
+ percpu_pool->obj_free = 0;
+
+ return 0;
+}
+#endif
+
/*
* We run out of memory. That means we probably have tons of objects
* allocated.
@@ -1367,6 +1387,11 @@ void __init debug_objects_mem_init(void)
} else
debug_objects_selftest();

+#ifdef CONFIG_HOTPLUG_CPU
+ cpuhp_setup_state_nocalls(CPUHP_DEBUG_OBJ_DEAD, "object:offline", NULL,
+ object_cpu_offline);
+#endif
+
/*
* Increase the thresholds for allocating and freeing objects
* according to the number of possible CPUs available in the system.