[PATCH 9/9] oom, oom_reaper: protect oom_reaper_list using simpler way

Michal Hocko
2016-03-22T11:02:41Z

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

"oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task" tried
to protect oom_reaper_list using MMF_OOM_KILLED flag. But we can do it
by simply checking tsk->oom_reaper_list != NULL.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
---
include/linux/sched.h | 2 --
mm/oom_kill.c | 8 ++------
2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index d118445a332e..78434d4f85f2 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -511,8 +511,6 @@ static inline int get_dumpable(struct mm_struct *mm)
#define MMF_HAS_UPROBES 19 /* has uprobes */
#define MMF_RECALC_UPROBES 20 /* MMF_HAS_UPROBES can be wrong */

-#define MMF_OOM_KILLED 21 /* OOM killer has chosen this mm */
-
#define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)

struct sighand_struct {
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index bed2885d10b0..cfafb91ebcd9 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -546,7 +546,7 @@ static int oom_reaper(void *unused)

static void wake_oom_reaper(struct task_struct *tsk)
{
- if (!oom_reaper_th)
+ if (!oom_reaper_th || tsk->oom_reaper_list)
return;

get_task_struct(tsk);
@@ -680,7 +680,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
unsigned int victim_points = 0;
static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
- bool can_oom_reap;
+ bool can_oom_reap = true;

/*
* If the task is already exiting, don't alarm the sysadmin or kill
@@ -742,10 +742,6 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
/* Get a reference to safely compare mm after task_unlock(victim) */
mm = victim->mm;
atomic_inc(&mm->mm_count);
-
- /* Make sure we do not try to oom reap the mm multiple times */
- can_oom_reap = !test_and_set_bit(MMF_OOM_KILLED, &mm->flags);
-
/*
* We should send SIGKILL before setting TIF_MEMDIE in order to prevent
* the OOM victim from depleting the memory reserves from the user
--
2.7.0