[PATCH 4/9] mm, oom_reaper: report success/failure

Michal Hocko
2016-03-22T11:03:10Z

From: Michal Hocko <mhocko@suse.com>

Inform about the successful/failed oom_reaper attempts and dump all the
held locks to tell us more who is blocking the progress.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
mm/oom_kill.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 2830b1c6483e..e627ce235e38 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -419,6 +419,7 @@ static struct task_struct *oom_reaper_th;
static struct task_struct *task_to_reap;
static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait);

+#define K(x) ((x) << (PAGE_SHIFT-10))
static bool __oom_reap_task(struct task_struct *tsk)
{
struct mmu_gather tlb;
@@ -479,6 +480,11 @@ static bool __oom_reap_task(struct task_struct *tsk)
&details);
}
tlb_finish_mmu(&tlb, 0, -1);
+ pr_info("oom_reaper: reaped process %d (%s), now anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
+ task_pid_nr(tsk), tsk->comm,
+ K(get_mm_counter(mm, MM_ANONPAGES)),
+ K(get_mm_counter(mm, MM_FILEPAGES)),
+ K(get_mm_counter(mm, MM_SHMEMPAGES)));
up_read(&mm->mmap_sem);

/*
@@ -495,14 +501,21 @@ static bool __oom_reap_task(struct task_struct *tsk)
return ret;
}

+#define MAX_OOM_REAP_RETRIES 10
static void oom_reap_task(struct task_struct *tsk)
{
int attempts = 0;

/* Retry the down_read_trylock(mmap_sem) a few times */
- while (attempts++ < 10 && !__oom_reap_task(tsk))
+ while (attempts++ < MAX_OOM_REAP_RETRIES && !__oom_reap_task(tsk))
schedule_timeout_idle(HZ/10);

+ if (attempts > MAX_OOM_REAP_RETRIES) {
+ pr_info("oom_reaper: unable to reap pid:%d (%s)\n",
+ task_pid_nr(tsk), tsk->comm);
+ debug_show_all_locks();
+ }
+
/* Drop a reference taken by wake_oom_reaper */
put_task_struct(tsk);
}
@@ -649,7 +662,6 @@ static bool process_shares_mm(struct task_struct *p, struct mm_struct *mm)
return false;
}

-#define K(x) ((x) << (PAGE_SHIFT-10))
/*
* Must be called while holding a reference to p, which will be released upon
* returning.
--
2.7.0