From: Richard Weinberger <richard-/L3Ra7n9ekc@public.gmane.org>
To: Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org,
mhocko-AlSwsSmVLrQ@public.gmane.org,
bsingharora-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org,
akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org,
vdavydov-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org,
tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
handai.szj-3b8fjiQLQpfQT0dZR+AlfA@public.gmane.org,
rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org,
rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org,
kirill.shutemov-VuQAYsv1563Yd54FQh9/CA@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org
Subject: Re: [RFC][PATCH] oom: Be less verbose if the oom_control event fd has listeners
Date: Thu, 05 Jun 2014 17:46:57 +0200 [thread overview]
Message-ID: <539090F1.7090408@nod.at> (raw)
In-Reply-To: <20140605141841.GA23796-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Am 05.06.2014 16:18, schrieb Oleg Nesterov:
> On 06/05, Richard Weinberger wrote:
>>
>> +int mem_cgroup_has_listeners(struct mem_cgroup *memcg)
>> +{
>> + int ret = 0;
>> +
>> + if (!memcg)
>> + goto out;
>> +
>> + spin_lock(&memcg_oom_lock);
>> + ret = !list_empty(&memcg->oom_notify);
>> + spin_unlock(&memcg_oom_lock);
>> +
>> +out:
>> + return ret;
>> +}
>
> Do we really need memcg_oom_lock to check list_empty() ? With or without
> this lock we can race with list_add/del anyway, and I guess we do not care.
Hmm, in mm/memcontrol.c all list_dev/add are under memcg_oom_lock.
What do I miss?
Thanks,
//richard
WARNING: multiple messages have this Message-ID (diff)
From: Richard Weinberger <richard@nod.at>
To: Oleg Nesterov <oleg@redhat.com>
Cc: hannes@cmpxchg.org, mhocko@suse.cz, bsingharora@gmail.com,
kamezawa.hiroyu@jp.fujitsu.com, akpm@linux-foundation.org,
vdavydov@parallels.com, tj@kernel.org, handai.szj@taobao.com,
rientjes@google.com, rusty@rustcorp.com.au,
kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org,
cgroups@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC][PATCH] oom: Be less verbose if the oom_control event fd has listeners
Date: Thu, 05 Jun 2014 17:46:57 +0200 [thread overview]
Message-ID: <539090F1.7090408@nod.at> (raw)
In-Reply-To: <20140605141841.GA23796@redhat.com>
Am 05.06.2014 16:18, schrieb Oleg Nesterov:
> On 06/05, Richard Weinberger wrote:
>>
>> +int mem_cgroup_has_listeners(struct mem_cgroup *memcg)
>> +{
>> + int ret = 0;
>> +
>> + if (!memcg)
>> + goto out;
>> +
>> + spin_lock(&memcg_oom_lock);
>> + ret = !list_empty(&memcg->oom_notify);
>> + spin_unlock(&memcg_oom_lock);
>> +
>> +out:
>> + return ret;
>> +}
>
> Do we really need memcg_oom_lock to check list_empty() ? With or without
> this lock we can race with list_add/del anyway, and I guess we do not care.
Hmm, in mm/memcontrol.c all list_dev/add are under memcg_oom_lock.
What do I miss?
Thanks,
//richard
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WARNING: multiple messages have this Message-ID (diff)
From: Richard Weinberger <richard@nod.at>
To: Oleg Nesterov <oleg@redhat.com>
Cc: hannes@cmpxchg.org, mhocko@suse.cz, bsingharora@gmail.com,
kamezawa.hiroyu@jp.fujitsu.com, akpm@linux-foundation.org,
vdavydov@parallels.com, tj@kernel.org, handai.szj@taobao.com,
rientjes@google.com, rusty@rustcorp.com.au,
kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org,
cgroups@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC][PATCH] oom: Be less verbose if the oom_control event fd has listeners
Date: Thu, 05 Jun 2014 17:46:57 +0200 [thread overview]
Message-ID: <539090F1.7090408@nod.at> (raw)
In-Reply-To: <20140605141841.GA23796@redhat.com>
Am 05.06.2014 16:18, schrieb Oleg Nesterov:
> On 06/05, Richard Weinberger wrote:
>>
>> +int mem_cgroup_has_listeners(struct mem_cgroup *memcg)
>> +{
>> + int ret = 0;
>> +
>> + if (!memcg)
>> + goto out;
>> +
>> + spin_lock(&memcg_oom_lock);
>> + ret = !list_empty(&memcg->oom_notify);
>> + spin_unlock(&memcg_oom_lock);
>> +
>> +out:
>> + return ret;
>> +}
>
> Do we really need memcg_oom_lock to check list_empty() ? With or without
> this lock we can race with list_add/del anyway, and I guess we do not care.
Hmm, in mm/memcontrol.c all list_dev/add are under memcg_oom_lock.
What do I miss?
Thanks,
//richard
next prev parent reply other threads:[~2014-06-05 15:46 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-05 14:00 oom: Be less verbose Richard Weinberger
2014-06-05 14:00 ` Richard Weinberger
2014-06-05 14:00 ` [RFC][PATCH] oom: Be less verbose if the oom_control event fd has listeners Richard Weinberger
2014-06-05 14:00 ` Richard Weinberger
2014-06-05 14:18 ` Oleg Nesterov
2014-06-05 14:18 ` Oleg Nesterov
[not found] ` <20140605141841.GA23796-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-06-05 15:46 ` Richard Weinberger [this message]
2014-06-05 15:46 ` Richard Weinberger
2014-06-05 15:46 ` Richard Weinberger
2014-06-05 16:00 ` Oleg Nesterov
2014-06-05 16:00 ` Oleg Nesterov
[not found] ` <20140605160029.GA28812-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2014-06-05 16:10 ` Richard Weinberger
2014-06-05 16:10 ` Richard Weinberger
2014-06-05 16:10 ` Richard Weinberger
2014-06-05 15:00 ` Michal Hocko
2014-06-05 15:00 ` Michal Hocko
2014-06-05 15:55 ` Richard Weinberger
2014-06-05 15:55 ` Richard Weinberger
2014-06-05 16:18 ` Michal Hocko
2014-06-05 16:18 ` Michal Hocko
[not found] ` <20140605161807.GD15939-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org>
2014-06-05 21:58 ` Richard Weinberger
2014-06-05 21:58 ` Richard Weinberger
2014-06-05 21:58 ` Richard Weinberger
2014-06-05 21:01 ` David Rientjes
2014-06-05 21:01 ` David Rientjes
2014-06-06 9:10 ` Michal Hocko
2014-06-06 9:10 ` Michal Hocko
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