[PATCH v1 5/5] percpu: scoped objcg protection

Roman Gushchin
2023-09-29T18:01:43Z

Similar to slab and kmem, switch to a scope-based protection of the
objcg pointer to avoid.

Signed-off-by: Roman Gushchin (Cruise) <roman.gushchin@linux.dev>
---
mm/percpu.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index a7665de8485f..f53ba692d67a 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1628,14 +1628,12 @@ static bool pcpu_memcg_pre_alloc_hook(size_t size, gfp_t gfp,
if (!memcg_kmem_online() || !(gfp & __GFP_ACCOUNT))
return true;

- objcg = get_obj_cgroup_from_current();
+ objcg = current_obj_cgroup();
if (!objcg)
return true;

- if (obj_cgroup_charge(objcg, gfp, pcpu_obj_full_size(size))) {
- obj_cgroup_put(objcg);
+ if (obj_cgroup_charge(objcg, gfp, pcpu_obj_full_size(size)))
return false;
- }

*objcgp = objcg;
return true;
@@ -1649,6 +1647,7 @@ static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
return;

if (likely(chunk && chunk->obj_cgroups)) {
+ obj_cgroup_get(objcg);
chunk->obj_cgroups[off >> PCPU_MIN_ALLOC_SHIFT] = objcg;

rcu_read_lock();
@@ -1657,7 +1656,6 @@ static void pcpu_memcg_post_alloc_hook(struct obj_cgroup *objcg,
rcu_read_unlock();
} else {
obj_cgroup_uncharge(objcg, pcpu_obj_full_size(size));
- obj_cgroup_put(objcg);
}
}

--
2.42.0