On Tue, Dec 20, 2022 at 10:27:45AM -0800, Roman Gushchin wrote:
> To charge a freshly allocated kernel object to a memory cgroup, the
> kernel needs to obtain an objcg pointer. Currently it does it
> indirectly by obtaining the memcg pointer first and then calling to
> __get_obj_cgroup_from_memcg().
>
> Usually tasks spend their entire life belonging to the same object
> cgroup. So it makes sense to save the objcg pointer on task_struct
> directly, so it can be obtained faster. It requires some work on fork,
> exit and cgroup migrate paths, but these paths are way colder.
>
> The old indirect way is still used for remote memcg charging.
>
> Signed-off-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
This looks good too. Few comments below:
[...]
> +
> +#ifdef CONFIG_MEMCG_KMEM
> +static void mem_cgroup_kmem_attach(struct cgroup_taskset *tset)
> +{
> + struct task_struct *task;
> + struct cgroup_subsys_state *css;
> +
> + cgroup_taskset_for_each(task, css, tset) {
> + struct mem_cgroup *memcg;
> +
> + if (task->objcg)
> + obj_cgroup_put(task->objcg);
> +
> + rcu_read_lock();
> + memcg = container_of(css, struct mem_cgroup, css);
> + task->objcg = __get_obj_cgroup_from_memcg(memcg);
> + rcu_read_unlock();
> + }
> +}
> +#else
> +static void mem_cgroup_kmem_attach(struct cgroup_taskset *tset) {}
> +#endif /* CONFIG_MEMCG_KMEM */
> +
> +#if defined(CONFIG_MEMCG_KMEM) || defined(CONFIG_MEMCG_KMEM)
I think you want CONFIG_LRU_GEN in the above check.
> static void mem_cgroup_attach(struct cgroup_taskset *tset)
> {
> + mem_cgroup_lru_gen_attach(tset);
> + mem_cgroup_kmem_attach(tset);
> }
> -#endif /* CONFIG_LRU_GEN */
> +#endif
>
> static int seq_puts_memcg_tunable(struct seq_file *m, unsigned long value)
> {
> @@ -6816,9 +6872,15 @@ struct cgroup_subsys memory_cgrp_subsys = {
> .css_reset = mem_cgroup_css_reset,
> .css_rstat_flush = mem_cgroup_css_rstat_flush,
> .can_attach = mem_cgroup_can_attach,
> +#if defined(CONFIG_MEMCG_KMEM) || defined(CONFIG_MEMCG_KMEM)
Same here.
> .attach = mem_cgroup_attach,
> +#endif
> .cancel_attach = mem_cgroup_cancel_attach,
> .post_attach = mem_cgroup_move_task,
> +#ifdef CONFIG_MEMCG_KMEM
> + .fork = mem_cgroup_fork,
> + .exit = mem_cgroup_exit,
> +#endif
> .dfl_cftypes = memory_files,
> .legacy_cftypes = mem_cgroup_legacy_files,
> .early_init = 0,
> --
> 2.39.0
>
