From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Michal Hocko <mhocko@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, guro@fb.com,
kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org,
rientjes@google.com, yang.s@alibaba-inc.com,
Andrew Morton <akpm@linux-foundation.org>,
Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
syzbot <syzbot+77e6b28a7a7106ad0def@syzkaller.appspotmail.com>
Subject: Re: [PATCH v3] mm: memcontrol: Don't flood OOM messages with no eligible task.
Date: Thu, 18 Oct 2018 19:37:18 +0900 [thread overview]
Message-ID: <6bbb0449-1f22-4d05-9e2a-636965b7dbc6@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20181018065519.GV18839@dhcp22.suse.cz>
On 2018/10/18 15:55, Michal Hocko wrote:
> On Thu 18-10-18 11:46:50, Tetsuo Handa wrote:
>> This is essentially a ratelimit approach, roughly equivalent with:
>>
>> static DEFINE_RATELIMIT_STATE(oom_no_victim_rs, 60 * HZ, 1);
>> oom_no_victim_rs.flags |= RATELIMIT_MSG_ON_RELEASE;
>>
>> if (__ratelimit(&oom_no_victim_rs)) {
>> dump_header(oc, NULL);
>> pr_warn("Out of memory and no killable processes...\n");
>> oom_no_victim_rs.begin = jiffies;
>> }
>
> Then there is no reason to reinvent the wheel. So use the standard
> ratelimit approach. Or put it in other words, this place is no special
> to any other that needs some sort of printk throttling. We surely do not
> want an ad-hoc solutions all over the kernel.
netdev_wait_allrefs() in net/core/dev.c is doing the same thing. Since
out_of_memory() is serialized by oom_lock mutex, there is no need to use
"struct ratelimit_state"->lock field. Plain "unsigned long" is enough.
>
> And once you realize that the ratelimit api is the proper one (put aside
> any potential improvements in the implementation of this api) then you
> quickly learn that we already do throttle oom reports and it would be
> nice to unify that and ... we are back to a naked patch. So please stop
> being stuborn and try to cooperate finally.
I don't think that ratelimit API is the proper one, for I am touching
"struct ratelimit_state"->begin field which is not exported by ratelimit API.
But if you insist on ratelimit API version, I can tolerate with below one.
mm/oom_kill.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index f10aa53..7c6118e 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -1106,6 +1106,12 @@ bool out_of_memory(struct oom_control *oc)
select_bad_process(oc);
/* Found nothing?!?! */
if (!oc->chosen) {
+ static DEFINE_RATELIMIT_STATE(no_eligible_rs, 60 * HZ, 1);
+
+ ratelimit_set_flags(&no_eligible_rs, RATELIMIT_MSG_ON_RELEASE);
+ if ((is_sysrq_oom(oc) || is_memcg_oom(oc)) &&
+ !__ratelimit(&no_eligible_rs))
+ return false;
dump_header(oc, NULL);
pr_warn("Out of memory and no killable processes...\n");
/*
@@ -1115,6 +1121,7 @@ bool out_of_memory(struct oom_control *oc)
*/
if (!is_sysrq_oom(oc) && !is_memcg_oom(oc))
panic("System is deadlocked on memory\n");
+ no_eligible_rs.begin = jiffies;
}
if (oc->chosen && oc->chosen != (void *)-1UL)
oom_kill_process(oc, !is_memcg_oom(oc) ? "Out of memory" :
--
1.8.3.1
next prev parent reply other threads:[~2018-10-18 10:37 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-17 10:06 [PATCH v3] mm: memcontrol: Don't flood OOM messages with no eligible task Tetsuo Handa
2018-10-17 10:28 ` Michal Hocko
2018-10-17 11:17 ` Sergey Senozhatsky
2018-10-17 11:29 ` Michal Hocko
2018-10-18 2:46 ` Tetsuo Handa
2018-10-18 4:27 ` Sergey Senozhatsky
2018-10-18 5:26 ` Tetsuo Handa
2018-10-18 6:10 ` Sergey Senozhatsky
2018-10-18 7:56 ` Michal Hocko
2018-10-18 8:13 ` Sergey Senozhatsky
2018-10-18 11:58 ` Tetsuo Handa
2018-10-18 23:54 ` Sergey Senozhatsky
2018-10-19 10:35 ` Tetsuo Handa
2018-10-23 0:47 ` Sergey Senozhatsky
2018-10-23 8:37 ` Petr Mladek
2018-10-23 8:54 ` Michal Hocko
2018-10-18 14:30 ` Petr Mladek
2018-10-19 0:18 ` Tetsuo Handa
2018-10-23 8:21 ` Petr Mladek
2018-10-23 10:23 ` Tetsuo Handa
2018-10-18 6:55 ` Michal Hocko
2018-10-18 10:37 ` Tetsuo Handa [this message]
2018-10-18 11:23 ` Michal Hocko
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