linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Michal Hocko <mhocko@kernel.org>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Greg Thelen <gthelen@google.com>,
	Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	Dmitry Vyukov <dvyukov@google.com>, <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: [PATCH 2/2] memcg, oom: emit oom report when there is no eligible task
Date: Wed,  8 Aug 2018 09:13:01 +0200	[thread overview]
Message-ID: <20180808071301.12478-3-mhocko@kernel.org> (raw)
In-Reply-To: <20180808071301.12478-1-mhocko@kernel.org>

From: Michal Hocko <mhocko@suse.com>

Johannes had doubts that the current WARN in the memcg oom path
when there is no eligible task is not all that useful because it doesn't
really give any useful insight into the memcg state. My original
intention was to make this lightweight but it is true that seeing
a stack trace will likely be not sufficient when somebody gets back to
us and report this warning.

Therefore replace the current warning by the full oom report which will
give us not only the back trace of the offending path but also the full
memcg state - memory counters and existing tasks.

Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 include/linux/oom.h |  2 ++
 mm/memcontrol.c     | 24 +++++++++++++-----------
 mm/oom_kill.c       |  8 ++++----
 3 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/include/linux/oom.h b/include/linux/oom.h
index a16a155a0d19..7424f9673cd1 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -133,6 +133,8 @@ extern struct task_struct *find_lock_task_mm(struct task_struct *p);
 
 extern int oom_evaluate_task(struct task_struct *task, void *arg);
 
+extern void dump_oom_header(struct oom_control *oc, struct task_struct *victim);
+
 /* sysctls */
 extern int sysctl_oom_dump_tasks;
 extern int sysctl_oom_kill_allocating_task;
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c80e5b6a8e9f..3d7c90e6c235 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1390,6 +1390,19 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
 	mutex_lock(&oom_lock);
 	ret = out_of_memory(&oc);
 	mutex_unlock(&oom_lock);
+
+	/*
+	 * under rare race the current task might have been selected while
+	 * reaching mem_cgroup_out_of_memory and there is no other oom victim
+	 * left. There is still no reason to warn because this task will
+	 * die and release its bypassed charge eventually.
+	 */
+	if (tsk_is_oom_victim(current))
+		return ret;
+
+	pr_warn("Memory cgroup charge failed because of no reclaimable memory! "
+		"This looks like a misconfiguration or a kernel bug.");
+	dump_oom_header(&oc, NULL);
 	return ret;
 }
 
@@ -1706,17 +1719,6 @@ static enum oom_status mem_cgroup_oom(struct mem_cgroup *memcg, gfp_t mask, int
 	if (mem_cgroup_out_of_memory(memcg, mask, order))
 		return OOM_SUCCESS;
 	
-	/*
-	 * under rare race the current task might have been selected while
-	 * reaching mem_cgroup_out_of_memory and there is no other oom victim
-	 * left. There is still no reason to warn because this task will
-	 * die and release its bypassed charge eventually.
-	 */
-	if (tsk_is_oom_victim(current))
-		return OOM_SUCCESS;
-
-	WARN(1,"Memory cgroup charge failed because of no reclaimable memory! "
-		"This looks like a misconfiguration or a kernel bug.");
 	return OOM_FAILED;
 }
 
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 104ef4a01a55..8918640fcb85 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -428,7 +428,7 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
 	rcu_read_unlock();
 }
 
-static void dump_header(struct oom_control *oc, struct task_struct *p)
+void dump_oom_header(struct oom_control *oc, struct task_struct *p)
 {
 	pr_warn("%s invoked oom-killer: gfp_mask=%#x(%pGg), order=%d, oom_score_adj=%hd\n",
 		current->comm, oc->gfp_mask, &oc->gfp_mask, oc->order,
@@ -945,7 +945,7 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
 	task_unlock(p);
 
 	if (__ratelimit(&oom_rs))
-		dump_header(oc, p);
+		dump_oom_header(oc, p);
 
 	pr_err("%s: Kill process %d (%s) score %u or sacrifice child\n",
 		message, task_pid_nr(p), p->comm, points);
@@ -1039,7 +1039,7 @@ static void check_panic_on_oom(struct oom_control *oc)
 	/* Do not panic for oom kills triggered by sysrq */
 	if (is_sysrq_oom(oc))
 		return;
-	dump_header(oc, NULL);
+	dump_oom_header(oc, NULL);
 	panic("Out of memory: %s panic_on_oom is enabled\n",
 		sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
 }
@@ -1129,7 +1129,7 @@ bool out_of_memory(struct oom_control *oc)
 	select_bad_process(oc);
 	/* Found nothing?!?! Either we hang forever, or we panic. */
 	if (!oc->chosen_task && !is_sysrq_oom(oc) && !is_memcg_oom(oc)) {
-		dump_header(oc, NULL);
+		dump_oom_header(oc, NULL);
 		panic("Out of memory and no killable processes...\n");
 	}
 	if (oc->chosen_task && oc->chosen_task != INFLIGHT_VICTIM)
-- 
2.18.0


  parent reply	other threads:[~2018-08-08  7:13 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-07  7:25 [PATCH] memcg, oom: be careful about races when warning about no reclaimable task Michal Hocko
2018-08-07 10:15 ` Tetsuo Handa
2018-08-07 11:04   ` Michal Hocko
2018-08-07 20:19   ` Johannes Weiner
2018-08-07 20:38     ` Tetsuo Handa
2018-08-08 12:57       ` Tetsuo Handa
2018-08-08 13:16         ` Michal Hocko
2018-08-07 20:02 ` Johannes Weiner
2018-08-07 20:23   ` Michal Hocko
2018-08-07 20:54     ` Johannes Weiner
2018-08-08  6:44       ` Michal Hocko
2018-08-08  7:12         ` Michal Hocko
2018-08-08  7:13           ` [PATCH 1/2] " Michal Hocko
2018-08-08  7:13           ` Michal Hocko [this message]
2018-08-08 14:45             ` [PATCH 2/2] memcg, oom: emit oom report when there is no eligible task Johannes Weiner
2018-08-08 16:17               ` Michal Hocko
2018-08-21 14:06                 ` Michal Hocko
2018-08-21 17:20                   ` Johannes Weiner

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180808071301.12478-3-mhocko@kernel.org \
    --to=mhocko@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=dvyukov@google.com \
    --cc=gthelen@google.com \
    --cc=hannes@cmpxchg.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@suse.com \
    --cc=penguin-kernel@I-love.SAKURA.ne.jp \
    --cc=vdavydov.dev@gmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).