[PATCH RFC 5/9] mm: add methord to charge percpu address

Yafang Shao
2022-03-08T13:11:25Z

This patch adds a methord to charge or uncharge a percpu address.
It is similar to free_percpu except that it doesn't touch the related
pages while does account only.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
include/linux/percpu.h | 1 +
mm/percpu.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 51 insertions(+)

diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index f1ec5ad..1a65221 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -128,6 +128,7 @@ extern int __init pcpu_page_first_chunk(size_t reserved_size,
extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp) __alloc_size(1);
extern void __percpu *__alloc_percpu(size_t size, size_t align) __alloc_size(1);
extern void free_percpu(void __percpu *__pdata);
+void charge_percpu(void __percpu *__pdata, bool charge);
extern phys_addr_t per_cpu_ptr_to_phys(void *addr);

#define alloc_percpu_gfp(type, gfp) \
diff --git a/mm/percpu.c b/mm/percpu.c
index ea28db2..22fc0ff 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -2309,6 +2309,56 @@ void free_percpu(void __percpu *ptr)
}
EXPORT_SYMBOL_GPL(free_percpu);

+void charge_percpu(void __percpu *ptr, bool charge)
+{
+ int bit_off, off, bits, size, end;
+ struct obj_cgroup *objcg;
+ struct pcpu_chunk *chunk;
+ unsigned long flags;
+ void *addr;
+
+ WARN_ON(!in_task());
+
+ if (!ptr)
+ return;
+
+ addr = __pcpu_ptr_to_addr(ptr);
+ spin_lock_irqsave(&pcpu_lock, flags);
+ chunk = pcpu_chunk_addr_search(addr);
+ off = addr - chunk->base_addr;
+ objcg = chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT];
+ if (!objcg) {
+ spin_unlock_irqrestore(&pcpu_lock, flags);
+ return;
+ }
+
+ bit_off = off / PCPU_MIN_ALLOC_SIZE;
+ /* find end index */
+ end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk),
+ bit_off + 1);
+ bits = end - bit_off;
+ size = bits * PCPU_MIN_ALLOC_SIZE;
+
+ if (charge) {
+ obj_cgroup_get(objcg);
+ obj_cgroup_charge(objcg, GFP_KERNEL, size * num_possible_cpus());
+ rcu_read_lock();
+ mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
+ (size * num_possible_cpus()));
+ rcu_read_unlock();
+ } else {
+ obj_cgroup_uncharge(objcg, size * num_possible_cpus());
+ rcu_read_lock();
+ mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_PERCPU_B,
+ -(size * num_possible_cpus()));
+ rcu_read_unlock();
+ obj_cgroup_put(objcg);
+ }
+
+ spin_unlock_irqrestore(&pcpu_lock, flags);
+}
+EXPORT_SYMBOL(charge_percpu);
+
bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr)
{
#ifdef CONFIG_SMP
--
1.8.3.1