From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751231AbdE3SxL (ORCPT ); Tue, 30 May 2017 14:53:11 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:37185 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750913AbdE3SxI (ORCPT ); Tue, 30 May 2017 14:53:08 -0400 Authentication-Results: kernel.org; dkim=none (message not signed) header.d=none;kernel.org; dmarc=none action=none header.from=fb.com; Date: Tue, 30 May 2017 19:52:31 +0100 From: Roman Gushchin To: Michal Hocko CC: Tetsuo Handa , Johannes Weiner , Vladimir Davydov , , , Subject: Re: [PATCH v2] mm,oom: add tracepoints for oom reaper-related events Message-ID: <20170530185231.GA13412@castle> References: <1496145932-18636-1-git-send-email-guro@fb.com> <20170530123415.GF7969@dhcp22.suse.cz> <20170530133335.GB28148@castle> <20170530134552.GI7969@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; 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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 Signed-off-by: Roman Gushchin Cc: Michal Hocko Cc: Tetsuo Handa Cc: Johannes Weiner Cc: Vladimir Davydov Cc: kernel-team@fb.com Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org --- include/trace/events/oom.h | 80 ++++++++++++++++++++++++++++++++++++++++++++++ mm/oom_kill.c | 7 ++++ 2 files changed, 87 insertions(+) diff --git a/include/trace/events/oom.h b/include/trace/events/oom.h index 38baeb2..c3c19d4 100644 --- a/include/trace/events/oom.h +++ b/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 --git a/mm/oom_kill.c b/mm/oom_kill.c index 04c9143..409b685 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -490,6 +490,7 @@ static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm) 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 task_struct *tsk, struct mm_struct *mm) */ 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 task_struct *tsk, struct mm_struct *mm) * 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_struct *tsk) 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_struct *tsk) */ __thaw_task(tsk); atomic_inc(&oom_victims); + trace_mark_victim(tsk->pid); } /** -- 2.7.4 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id 159CB6B0279 for ; Tue, 30 May 2017 14:53:10 -0400 (EDT) Received: by mail-pf0-f197.google.com with SMTP id e131so107933876pfh.7 for ; Tue, 30 May 2017 11:53:10 -0700 (PDT) Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com. 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