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anolis: kfence: Use a inner refcnt to track kpa itself 

ANBZ: #8917

We used to decide when to kfree(kpa) by on_rb_tree, but it is not so
accurate. Unlike kpa->refcnt (which is used to protect kfence pool), add
a new inner kpa->_ref to track kpa itself.

Fixes: 3bc27d45db ("anolis: kfence: introduce pool_mode and auto distribute pools to nodes")
Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>
Reviewed-by: Xu Yu <xuyu@linux.alibaba.com>
Link: https://gitee.com/anolis/cloud-kernel/pulls/3122
This commit is contained in:
Tianchen Ding 2024-04-29 11:09:28 +08:00 committed by 小龙
parent a87c4c8699
commit b7493a9053
2 changed files with 18 additions and 7 deletions
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2
include/linux/kfence.h
View File

@ -22,10 +22,10 @@ struct kfence_pool_area {
unsigned long pool_size; /* size of kfence pool of this area */
unsigned long nr_objects; /* max object number of this area, 0 marked as zombie area */
int node; /* the numa node this area belongs to */
atomic_t _ref; /* count kpa ref, to protect kpa itself */
struct list_head list; /* ready to be added to kfence_pool_root */
struct percpu_ref refcnt; /* count in use objects */
struct work_struct work; /* use workqueue to free unused area */
bool on_rb_tree; /* whether this kpa is on rb tree */
};
#ifdef CONFIG_KFENCE

23
mm/kfence/core.c
View File

@ -1082,6 +1082,7 @@ static inline bool __init_kpa(struct kfence_pool_area *kpa, char *__kfence_pool,
kpa->pool_size = pool_size;
kpa->nr_objects = nr_objects;
kpa->node = node;
atomic_set(&kpa->_ref, 1); /* held by rb tree */
if (!__kfence_init_pool_area(kpa))
goto fail;
@ -1117,7 +1118,6 @@ static bool __init kfence_init_pool_area(int node, int area)
rb_add(&kpa->rb_node, &kfence_pool_root, kfence_rb_less);
__kfence_pool_area[index] = NULL;
kpa->on_rb_tree = true;
kfence_num_objects_stat[node].allocated += nr_objects;
return true;
@ -1207,6 +1207,17 @@ static inline void kfence_free_pool_late_area(struct kfence_pool_area *kpa)
free_contig_range(page_to_pfn(virt_to_page(kpa->addr)), kpa->pool_size / PAGE_SIZE);
}
static void get_kpa(struct kfence_pool_area *kpa)
{
atomic_inc(&kpa->_ref);
}
static void put_kpa(struct kfence_pool_area *kpa)
{
if (atomic_dec_and_test(&kpa->_ref))
kfree(kpa);
}
static int kfence_update_pool_root(void *info)
{
struct list_head *ready_list = info;
@ -1218,7 +1229,7 @@ static int kfence_update_pool_root(void *info)
next = rb_next(cur);
if (!kpa->nr_objects) {
rb_erase(&kpa->rb_node, &kfence_pool_root);
kfree(kpa);
put_kpa(kpa);
} else {
percpu_ref_resurrect(&kpa->refcnt);
}
@ -1227,7 +1238,6 @@ static int kfence_update_pool_root(void *info)
while (!list_empty(ready_list)) {
kpa = list_first_entry(ready_list, struct kfence_pool_area, list);
rb_add(&kpa->rb_node, &kfence_pool_root, kfence_rb_less);
kpa->on_rb_tree = true;
list_del(&kpa->list);
}
@ -1374,18 +1384,19 @@ static void kfence_free_area(struct work_struct *work)
percpu_ref_exit(&kpa->refcnt);
kpa->nr_objects = 0;
kpa->pool_size = 0;
if (!kpa->on_rb_tree)
kfree(kpa);
out_unlock:
mutex_unlock(&kfence_mutex);
put_kpa(kpa);
}
static void kpa_release(struct percpu_ref *ref)
{
struct kfence_pool_area *kpa = container_of(ref, struct kfence_pool_area, refcnt);
queue_work(system_long_wq, &kpa->work);
get_kpa(kpa);
if (!queue_work(system_long_wq, &kpa->work))
put_kpa(kpa);
}
static void calculate_need_alloc(void)