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mm, oom: remove redundant task_in_mem_cgroup() check

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oom_unkillable_task() can be called from three different contexts i.e.
global OOM, memcg OOM and oom_score procfs interface.  At the moment
oom_unkillable_task() does a task_in_mem_cgroup() check on the given
process.  Since there is no reason to perform task_in_mem_cgroup()
check for global OOM and oom_score procfs interface, those contexts
provide NULL memcg and skips the task_in_mem_cgroup() check.  However
for memcg OOM context, the oom_unkillable_task() is always called from
mem_cgroup_scan_tasks() and thus task_in_mem_cgroup() check becomes
redundant and effectively dead code.  So, just remove the
task_in_mem_cgroup() check altogether.

Link: http://lkml.kernel.org/r/20190624212631.87212-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Paul Jackson <pj@sgi.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Shakeel Butt 2019-07-11 21:00:26 -07:00 committed by Linus Torvalds
parent 5eee7e1cdb
commit 6ba749ee78
5 changed files with 9 additions and 47 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
fs/proc/base.c
View File

@ -532,7 +532,7 @@ static int proc_oom_score(struct seq_file *m, struct pid_namespace *ns,
unsigned long totalpages = totalram_pages() + total_swap_pages;
unsigned long points = 0;
points = oom_badness(task, NULL, NULL, totalpages) *
points = oom_badness(task, NULL, totalpages) *
1000 / totalpages;
seq_printf(m, "%lu\n", points);

7
include/linux/memcontrol.h
View File

@ -394,7 +394,6 @@ out:
struct lruvec *mem_cgroup_page_lruvec(struct page *, struct pglist_data *);
bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg);
struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
@ -875,12 +874,6 @@ static inline bool mm_match_cgroup(struct mm_struct *mm,
return true;
}
static inline bool task_in_mem_cgroup(struct task_struct *task,
const struct mem_cgroup *memcg)
{
return true;
}
static inline struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
{
return NULL;

2
include/linux/oom.h
View File

@ -108,7 +108,7 @@ static inline vm_fault_t check_stable_address_space(struct mm_struct *mm)
bool __oom_reap_task_mm(struct mm_struct *mm);
extern unsigned long oom_badness(struct task_struct *p,
struct mem_cgroup *memcg, const nodemask_t *nodemask,
const nodemask_t *nodemask,
unsigned long totalpages);
extern bool out_of_memory(struct oom_control *oc);

26
mm/memcontrol.c
View File

@ -1259,32 +1259,6 @@ void mem_cgroup_update_lru_size(struct lruvec *lruvec, enum lru_list lru,
*lru_size += nr_pages;
}
bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg)
{
struct mem_cgroup *task_memcg;
struct task_struct *p;
bool ret;
p = find_lock_task_mm(task);
if (p) {
task_memcg = get_mem_cgroup_from_mm(p->mm);
task_unlock(p);
} else {
/*
* All threads may have already detached their mm's, but the oom
* killer still needs to detect if they have already been oom
* killed to prevent needlessly killing additional tasks.
*/
rcu_read_lock();
task_memcg = mem_cgroup_from_task(task);
css_get(&task_memcg->css);
rcu_read_unlock();
}
ret = mem_cgroup_is_descendant(task_memcg, memcg);
css_put(&task_memcg->css);
return ret;
}
/**
* mem_cgroup_margin - calculate chargeable space of a memory cgroup
* @memcg: the memory cgroup

19
mm/oom_kill.c
View File

@ -153,17 +153,13 @@ static inline bool is_memcg_oom(struct oom_control *oc)
/* return true if the task is not adequate as candidate victim task. */
static bool oom_unkillable_task(struct task_struct *p,
struct mem_cgroup *memcg, const nodemask_t *nodemask)
const nodemask_t *nodemask)
{
if (is_global_init(p))
return true;
if (p->flags & PF_KTHREAD)
return true;
/* When mem_cgroup_out_of_memory() and p is not member of the group */
if (memcg && !task_in_mem_cgroup(p, memcg))
return true;
/* p may not have freeable memory in nodemask */
if (!has_intersects_mems_allowed(p, nodemask))
return true;
@ -194,20 +190,19 @@ static bool is_dump_unreclaim_slabs(void)
* oom_badness - heuristic function to determine which candidate task to kill
* @p: task struct of which task we should calculate
* @totalpages: total present RAM allowed for page allocation
* @memcg: task's memory controller, if constrained
* @nodemask: nodemask passed to page allocator for mempolicy ooms
*
* The heuristic for determining which task to kill is made to be as simple and
* predictable as possible. The goal is to return the highest value for the
* task consuming the most memory to avoid subsequent oom failures.
*/
unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
unsigned long oom_badness(struct task_struct *p,
const nodemask_t *nodemask, unsigned long totalpages)
{
long points;
long adj;
if (oom_unkillable_task(p, memcg, nodemask))
if (oom_unkillable_task(p, nodemask))
return 0;
p = find_lock_task_mm(p);
@ -318,7 +313,7 @@ static int oom_evaluate_task(struct task_struct *task, void *arg)
struct oom_control *oc = arg;
unsigned long points;
if (oom_unkillable_task(task, NULL, oc->nodemask))
if (oom_unkillable_task(task, oc->nodemask))
goto next;
/*
@ -342,7 +337,7 @@ static int oom_evaluate_task(struct task_struct *task, void *arg)
goto select;
}
points = oom_badness(task, NULL, oc->nodemask, oc->totalpages);
points = oom_badness(task, oc->nodemask, oc->totalpages);
if (!points || points < oc->chosen_points)
goto next;
@ -387,7 +382,7 @@ static int dump_task(struct task_struct *p, void *arg)
struct oom_control *oc = arg;
struct task_struct *task;
if (oom_unkillable_task(p, NULL, oc->nodemask))
if (oom_unkillable_task(p, oc->nodemask))
return 0;
task = find_lock_task_mm(p);
@ -1084,7 +1079,7 @@ bool out_of_memory(struct oom_control *oc)
check_panic_on_oom(oc);
if (!is_memcg_oom(oc) && sysctl_oom_kill_allocating_task &&
current->mm && !oom_unkillable_task(current, NULL, oc->nodemask) &&
current->mm && !oom_unkillable_task(current, oc->nodemask) &&
current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
get_task_struct(current);
oc->chosen = current;