percpu: scoped objcg protection

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

Link: https://lkml.kernel.org/r/20231019225346.1822282-6-roman.gushchin@linux.dev
Signed-off-by: Roman Gushchin (Cruise) <roman.gushchin@linux.dev>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Acked-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/percpu.c b/mm/percpu.c
index a7665de8485fd9594c523c68ad579b1303e1c4ba..f53ba692d67a6deb8a3f2bed750fef71e4af2e8b 100644 (file)
--- 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);
        }
 }