Commit df381975 authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
Browse files

memcg: get_mem_cgroup_from_mm()

Instead of returning NULL from try_get_mem_cgroup_from_mm() when the mm
owner is exiting, just return root_mem_cgroup.  This makes sense for all
callsites and gets rid of some of them having to fallback manually.

[ fix warnings]
Signed-off-by: default avatarJohannes Weiner <>
Signed-off-by: default avatarFengguang Wu <>
Acked-by: default avatarMichal Hocko <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 03583f1a
......@@ -94,7 +94,6 @@ bool task_in_mem_cgroup(struct task_struct *task,
extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page);
extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
extern struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm);
extern struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg);
extern struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css);
......@@ -294,11 +293,6 @@ static inline struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
return NULL;
static inline struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
return NULL;
static inline bool mm_match_cgroup(struct mm_struct *mm,
struct mem_cgroup *memcg)
......@@ -1071,7 +1071,7 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
return mem_cgroup_from_css(task_css(p, memory_cgrp_id));
struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
static struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
struct mem_cgroup *memcg = NULL;
......@@ -1079,7 +1079,7 @@ struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
do {
memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
if (unlikely(!memcg))
memcg = root_mem_cgroup;
} while (!css_tryget(&memcg->css));
return memcg;
......@@ -1475,7 +1475,7 @@ bool task_in_mem_cgroup(struct task_struct *task,
p = find_lock_task_mm(task);
if (p) {
curr = try_get_mem_cgroup_from_mm(p->mm);
curr = get_mem_cgroup_from_mm(p->mm);
} else {
......@@ -1489,8 +1489,6 @@ bool task_in_mem_cgroup(struct task_struct *task,
if (!curr)
return false;
* We should check use_hierarchy of "memcg" not "curr". Because checking
* use_hierarchy of "curr" here make this function true if hierarchy is
......@@ -3617,15 +3615,7 @@ __memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **_memcg, int order)
if (!current->mm || current->memcg_kmem_skip_account)
return true;
memcg = try_get_mem_cgroup_from_mm(current->mm);
* very rare case described in mem_cgroup_from_task. Unfortunately there
* isn't much we can do without complicating this too much, and it would
* be gfp-dependent anyway. Just let it go
if (unlikely(!memcg))
return true;
memcg = get_mem_cgroup_from_mm(current->mm);
if (!memcg_can_account_kmem(memcg)) {
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