Commit 88451f2c authored by Zqiang's avatar Zqiang Committed by Thomas Gleixner
Browse files

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: default avatarZqiang <qiang.zhang@windriver.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/r/20200908062709.11441-1-qiang.zhang@windriver.com
parent f9e62f31

include/linux/cpuhotplug.h

+1 −0
Original line number Diff line number Diff line
@@ -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,

lib/debugobjects.c

+25 −0
Original line number Diff line number Diff line
@@ -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.

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