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From: Shakeel Butt <shakeelb@google.com>
To: Mina Almasry <almasrymina@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jonathan Corbet <corbet@lwn.net>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Hugh Dickins <hughd@google.com>, Shuah Khan <shuah@kernel.org>,
	Greg Thelen <gthelen@google.com>,
	Dave Chinner <david@fromorbit.com>,
	Matthew Wilcox <willy@infradead.org>,
	Roman Gushchin <guro@fb.com>, "Theodore Ts'o" <tytso@mit.edu>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, cgroups@vger.kernel.org
Subject: Re: [PATCH v4 2/4] mm/oom: handle remote ooms
Date: Fri, 19 Nov 2021 23:58:21 -0800	[thread overview]
Message-ID: <CALvZod680y1o3WKFKEXmXf3Cd4j-POpc-zrAQ1+ykLoWK9-21A@mail.gmail.com> (raw)
In-Reply-To: <20211120045011.3074840-3-almasrymina@google.com>

On Fri, Nov 19, 2021 at 8:50 PM Mina Almasry <almasrymina@google.com> wrote:
>
[...]
> +/*
> + * Returns true if current's mm is a descendant of the memcg_under_oom (or
> + * equal to it). False otherwise. This is used by the oom-killer to detect
> + * ooms due to remote charging.
> + */
> +bool is_remote_oom(struct mem_cgroup *memcg_under_oom)
> +{
> +       struct mem_cgroup *current_memcg;
> +       bool is_remote_oom;
> +
> +       if (!memcg_under_oom)
> +               return false;
> +
> +       rcu_read_lock();
> +       current_memcg = mem_cgroup_from_task(current);
> +       if (current_memcg && !css_tryget_online(&current_memcg->css))

No need to grab a reference. You can call mem_cgroup_is_descendant() within rcu.

> +               current_memcg = NULL;
> +       rcu_read_unlock();
> +
> +       if (!current_memcg)
> +               return false;
> +
> +       is_remote_oom =
> +               !mem_cgroup_is_descendant(current_memcg, memcg_under_oom);
> +       css_put(&current_memcg->css);
> +
> +       return is_remote_oom;
> +}
> +

WARNING: multiple messages have this Message-ID (diff)
From: Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
To: Mina Almasry <almasrymina-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
	Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Vladimir Davydov
	<vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Jonathan Corbet <corbet-T1hC0tSOHrs@public.gmane.org>,
	Alexander Viro
	<viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>,
	Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Shuah Khan <shuah-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Greg Thelen <gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>,
	Dave Chinner <david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org>,
	Matthew Wilcox <willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
	Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>,
	Theodore Ts'o <tytso-3s7WtUTddSA@public.gmane.org>,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH v4 2/4] mm/oom: handle remote ooms
Date: Fri, 19 Nov 2021 23:58:21 -0800	[thread overview]
Message-ID: <CALvZod680y1o3WKFKEXmXf3Cd4j-POpc-zrAQ1+ykLoWK9-21A@mail.gmail.com> (raw)
In-Reply-To: <20211120045011.3074840-3-almasrymina-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>

On Fri, Nov 19, 2021 at 8:50 PM Mina Almasry <almasrymina-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> wrote:
>
[...]
> +/*
> + * Returns true if current's mm is a descendant of the memcg_under_oom (or
> + * equal to it). False otherwise. This is used by the oom-killer to detect
> + * ooms due to remote charging.
> + */
> +bool is_remote_oom(struct mem_cgroup *memcg_under_oom)
> +{
> +       struct mem_cgroup *current_memcg;
> +       bool is_remote_oom;
> +
> +       if (!memcg_under_oom)
> +               return false;
> +
> +       rcu_read_lock();
> +       current_memcg = mem_cgroup_from_task(current);
> +       if (current_memcg && !css_tryget_online(&current_memcg->css))

No need to grab a reference. You can call mem_cgroup_is_descendant() within rcu.

> +               current_memcg = NULL;
> +       rcu_read_unlock();
> +
> +       if (!current_memcg)
> +               return false;
> +
> +       is_remote_oom =
> +               !mem_cgroup_is_descendant(current_memcg, memcg_under_oom);
> +       css_put(&current_memcg->css);
> +
> +       return is_remote_oom;
> +}
> +

  parent reply	other threads:[~2021-11-20  7:58 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-20  4:50 [PATCH v4 0/4] Deterministic charging of shared memory Mina Almasry
2021-11-20  4:50 ` Mina Almasry
2021-11-20  4:50 ` [PATCH v4 1/4] mm: support deterministic memory charging of filesystems Mina Almasry
2021-11-20  4:50   ` Mina Almasry
2021-11-20  7:53   ` Shakeel Butt
2021-11-20  4:50 ` [PATCH v4 2/4] mm/oom: handle remote ooms Mina Almasry
2021-11-20  5:07   ` Matthew Wilcox
2021-11-20  5:07     ` Matthew Wilcox
2021-11-20  5:31     ` Mina Almasry
2021-11-20  7:58   ` Shakeel Butt [this message]
2021-11-20  7:58     ` Shakeel Butt
2021-11-20  4:50 ` [PATCH v4 3/4] mm, shmem: add filesystem memcg= option documentation Mina Almasry
2021-11-20  4:50 ` [PATCH v4 4/4] mm, shmem, selftests: add tmpfs memcg= mount option tests Mina Almasry
2021-11-20  5:01 ` [PATCH v4 0/4] Deterministic charging of shared memory Matthew Wilcox
2021-11-20  5:27   ` Mina Almasry
2021-11-22 19:04 ` Johannes Weiner
2021-11-22 22:09   ` Mina Almasry
2021-11-22 23:09   ` Roman Gushchin
2021-11-23 19:26     ` Mina Almasry
2021-11-23 20:21     ` Johannes Weiner
2021-11-23 21:19       ` Mina Almasry
2021-11-23 22:49         ` Roman Gushchin
2021-11-24 17:27   ` Michal Hocko
2021-11-29  6:00   ` Shakeel Butt

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