The patch titled
Subject: mm/oom_kill.c: add tracepoints for oom reaper-related events
has been added to the -mm tree. Its filename is
mmoom-add-tracepoints-for-oom-reaper-related-events.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mmoom-add-tracepoints-for-oom-reaper-related-events.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mmoom-add-tracepoints-for-oom-reaper-related-events.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Roman Gushchin <guro@xxxxxx>
Subject: mm/oom_kill.c: add tracepoints for oom reaper-related events
During the debugging of the problem described in
https://lkml.org/lkml/2017/5/17/542 and fixed by Tetsuo Handa in
https://lkml.org/lkml/2017/5/19/383 , I've found that the existing debug
output is not really useful to understand issues related to the oom
reaper.
So, I assume, that adding some tracepoints might help with debugging of
similar issues.
Trace the following events:
1) a process is marked as an oom victim,
2) a process is added to the oom reaper list,
3) the oom reaper starts reaping process's mm,
4) the oom reaper finished reaping,
5) the oom reaper skips reaping.
How it works in practice? Below is an example which show how the problem
mentioned above can be found: one process is added twice to the oom_reaper
list:
$ cd /sys/kernel/debug/tracing
$ echo "oom:mark_victim" > set_event
$ echo "oom:wake_reaper" >> set_event
$ echo "oom:skip_task_reaping" >> set_event
$ echo "oom:start_task_reaping" >> set_event
$ echo "oom:finish_task_reaping" >> set_event
$ cat trace_pipe
allocate-502 [001] .... 91.836405: mark_victim: pid=502
allocate-502 [001] .N.. 91.837356: wake_reaper: pid=502
allocate-502 [000] .N.. 91.871149: wake_reaper: pid=502
oom_reaper-23 [000] .... 91.871177: start_task_reaping: pid=502
oom_reaper-23 [000] .N.. 91.879511: finish_task_reaping: pid=502
oom_reaper-23 [000] .... 91.879580: skip_task_reaping: pid=502
Link: http://lkml.kernel.org/r/20170530185231.GA13412@castle
Signed-off-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/trace/events/oom.h | 80 +++++++++++++++++++++++++++++++++++
mm/oom_kill.c | 7 +++
2 files changed, 87 insertions(+)
diff -puN include/trace/events/oom.h~mmoom-add-tracepoints-for-oom-reaper-related-events include/trace/events/oom.h
--- a/include/trace/events/oom.h~mmoom-add-tracepoints-for-oom-reaper-related-events
+++ a/include/trace/events/oom.h
@@ -70,6 +70,86 @@ TRACE_EVENT(reclaim_retry_zone,
__entry->wmark_check)
);
+TRACE_EVENT(mark_victim,
+ TP_PROTO(int pid),
+
+ TP_ARGS(pid),
+
+ TP_STRUCT__entry(
+ __field(int, pid)
+ ),
+
+ TP_fast_assign(
+ __entry->pid = pid;
+ ),
+
+ TP_printk("pid=%d", __entry->pid)
+);
+
+TRACE_EVENT(wake_reaper,
+ TP_PROTO(int pid),
+
+ TP_ARGS(pid),
+
+ TP_STRUCT__entry(
+ __field(int, pid)
+ ),
+
+ TP_fast_assign(
+ __entry->pid = pid;
+ ),
+
+ TP_printk("pid=%d", __entry->pid)
+);
+
+TRACE_EVENT(start_task_reaping,
+ TP_PROTO(int pid),
+
+ TP_ARGS(pid),
+
+ TP_STRUCT__entry(
+ __field(int, pid)
+ ),
+
+ TP_fast_assign(
+ __entry->pid = pid;
+ ),
+
+ TP_printk("pid=%d", __entry->pid)
+);
+
+TRACE_EVENT(finish_task_reaping,
+ TP_PROTO(int pid),
+
+ TP_ARGS(pid),
+
+ TP_STRUCT__entry(
+ __field(int, pid)
+ ),
+
+ TP_fast_assign(
+ __entry->pid = pid;
+ ),
+
+ TP_printk("pid=%d", __entry->pid)
+);
+
+TRACE_EVENT(skip_task_reaping,
+ TP_PROTO(int pid),
+
+ TP_ARGS(pid),
+
+ TP_STRUCT__entry(
+ __field(int, pid)
+ ),
+
+ TP_fast_assign(
+ __entry->pid = pid;
+ ),
+
+ TP_printk("pid=%d", __entry->pid)
+);
+
#ifdef CONFIG_COMPACTION
TRACE_EVENT(compact_retry,
diff -puN mm/oom_kill.c~mmoom-add-tracepoints-for-oom-reaper-related-events mm/oom_kill.c
--- a/mm/oom_kill.c~mmoom-add-tracepoints-for-oom-reaper-related-events
+++ a/mm/oom_kill.c
@@ -490,6 +490,7 @@ static bool __oom_reap_task_mm(struct ta
if (!down_read_trylock(&mm->mmap_sem)) {
ret = false;
+ trace_skip_task_reaping(tsk->pid);
goto unlock_oom;
}
@@ -500,9 +501,12 @@ static bool __oom_reap_task_mm(struct ta
*/
if (!mmget_not_zero(mm)) {
up_read(&mm->mmap_sem);
+ trace_skip_task_reaping(tsk->pid);
goto unlock_oom;
}
+ trace_start_task_reaping(tsk->pid);
+
/*
* Tell all users of get_user/copy_from_user etc... that the content
* is no longer stable. No barriers really needed because unmapping
@@ -544,6 +548,7 @@ static bool __oom_reap_task_mm(struct ta
* put the oom_reaper out of the way.
*/
mmput_async(mm);
+ trace_finish_task_reaping(tsk->pid);
unlock_oom:
mutex_unlock(&oom_lock);
return ret;
@@ -615,6 +620,7 @@ static void wake_oom_reaper(struct task_
tsk->oom_reaper_list = oom_reaper_list;
oom_reaper_list = tsk;
spin_unlock(&oom_reaper_lock);
+ trace_wake_reaper(tsk->pid);
wake_up(&oom_reaper_wait);
}
@@ -666,6 +672,7 @@ static void mark_oom_victim(struct task_
*/
__thaw_task(tsk);
atomic_inc(&oom_victims);
+ trace_mark_victim(tsk->pid);
}
/**
_
Patches currently in -mm which might be from guro@xxxxxx are
mm-per-cgroup-memory-reclaim-stats.patch
mmoom-add-tracepoints-for-oom-reaper-related-events.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
