Re: [PATCH 2/2] vmalloc: Account memcg per vmalloc

On Wed, Dec 11, 2024 at 04:32:50AM +0000, Matthew Wilcox (Oracle) wrote: [...]

+int obj_cgroup_charge_vmalloc(struct obj_cgroup **objcgp,

• unsigned int nr_pages, gfp_t gfp)
  

+{

• struct obj_cgroup *objcg;
• int err;
• if (mem_cgroup_disabled() || !(gfp & __GFP_ACCOUNT))

• return 0;
  

• objcg = current_obj_cgroup();
• if (!objcg)

• return 0;
  

• err = obj_cgroup_charge_pages(objcg, gfp, nr_pages);
• if (err)

• return err;
  

• obj_cgroup_get(objcg);
• mod_memcg_state(obj_cgroup_memcg(objcg), MEMCG_VMALLOC, nr_pages);

obj_cgroup_memcg() needs to be within rcu. See MEMCG_PERCPU_B as an example.

• *objcgp = objcg;
• return 0;

+}

+/**

• • obj_cgroup_uncharge_vmalloc - Uncharge vmalloc memory
• • @objcg: The object cgroup
• • @nr_pages: Number of pages
• */

+void obj_cgroup_uncharge_vmalloc(struct obj_cgroup *objcg,

• unsigned int nr_pages)
  

+{

• if (!objcg)

• return;
  

• mod_memcg_state(objcg->memcg, MEMCG_VMALLOC, 0L - nr_pages);

Please use obj_cgroup_memcg() above instead of objcg->memcg and within rcu lock.

Overall the patch looks good.