mm: memcontrol: use mem_cgroup_is_root() helper

Replace the checks for memcg is root memcg, with mem_cgroup_is_root()
helper.

Link: https://lkml.kernel.org/r/20220930134433.338103-1-kamalesh.babulal@oracle.com
Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tom Hromatka <tom.hromatka@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 2d8549ae1b3004f78c244e578d3bf0ce36b0b844..f264a856ba86222538306abdf8d88a6fcc27f853 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1219,7 +1219,7 @@ static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg)
         * cgroup root (root_mem_cgroup). So we have to handle
         * dead_memcg from cgroup root separately.
         */
-       if (last != root_mem_cgroup)
+       if (!mem_cgroup_is_root(last))
                __invalidate_reclaim_iterators(root_mem_cgroup,
                                                dead_memcg);
 }
@@ -1243,7 +1243,7 @@ int mem_cgroup_scan_tasks(struct mem_cgroup *memcg,
        struct mem_cgroup *iter;
        int ret = 0;
 
-       BUG_ON(memcg == root_mem_cgroup);
+       BUG_ON(mem_cgroup_is_root(memcg));
 
        for_each_mem_cgroup_tree(iter, memcg) {
                struct css_task_iter it;
@@ -1272,7 +1272,7 @@ void lruvec_memcg_debug(struct lruvec *lruvec, struct folio *folio)
        memcg = folio_memcg(folio);
 
        if (!memcg)
-               VM_BUG_ON_FOLIO(lruvec_memcg(lruvec) != root_mem_cgroup, folio);
+               VM_BUG_ON_FOLIO(!mem_cgroup_is_root(lruvec_memcg(lruvec)), folio);
        else
                VM_BUG_ON_FOLIO(lruvec_memcg(lruvec) != memcg, folio);
 }
@@ -2036,7 +2036,7 @@ struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim,
        rcu_read_lock();
 
        memcg = mem_cgroup_from_task(victim);
-       if (memcg == root_mem_cgroup)
+       if (mem_cgroup_is_root(memcg))
                goto out;
 
        /*
@@ -2995,7 +2995,7 @@ static struct obj_cgroup *__get_obj_cgroup_from_memcg(struct mem_cgroup *memcg)
 {
        struct obj_cgroup *objcg = NULL;
 
-       for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) {
+       for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg)) {
                objcg = rcu_dereference(memcg->objcg);
                if (objcg && obj_cgroup_tryget(objcg))
                        break;
@@ -7163,7 +7163,7 @@ void mem_cgroup_sk_alloc(struct sock *sk)
 
        rcu_read_lock();
        memcg = mem_cgroup_from_task(current);
-       if (memcg == root_mem_cgroup)
+       if (mem_cgroup_is_root(memcg))
                goto out;
        if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && !memcg->tcpmem_active)
                goto out;
@@ -7298,7 +7298,7 @@ static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)
                 * The root cgroup cannot be destroyed, so it's refcount must
                 * always be >= 1.
                 */
-               if (WARN_ON_ONCE(memcg == root_mem_cgroup)) {
+               if (WARN_ON_ONCE(mem_cgroup_is_root(memcg))) {
                        VM_BUG_ON(1);
                        break;
                }
@@ -7462,7 +7462,7 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
 
        if (mem_cgroup_disabled() || do_memsw_account())
                return nr_swap_pages;
-       for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg))
+       for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg))
                nr_swap_pages = min_t(long, nr_swap_pages,
                                      READ_ONCE(memcg->swap.max) -
                                      page_counter_read(&memcg->swap));
@@ -7484,7 +7484,7 @@ bool mem_cgroup_swap_full(struct folio *folio)
        if (!memcg)
                return false;
 
-       for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) {
+       for (; !mem_cgroup_is_root(memcg); memcg = parent_mem_cgroup(memcg)) {
                unsigned long usage = page_counter_read(&memcg->swap);
 
                if (usage * 2 >= READ_ONCE(memcg->swap.high) ||
@@ -7648,7 +7648,7 @@ bool obj_cgroup_may_zswap(struct obj_cgroup *objcg)
                return true;
 
        original_memcg = get_mem_cgroup_from_objcg(objcg);
-       for (memcg = original_memcg; memcg != root_mem_cgroup;
+       for (memcg = original_memcg; !mem_cgroup_is_root(memcg);
             memcg = parent_mem_cgroup(memcg)) {
                unsigned long max = READ_ONCE(memcg->zswap_max);
                unsigned long pages;