From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: mhocko@kernel.org
Cc: linux-mm@kvack.org, rientjes@google.com, oleg@redhat.com,
vdavydov@parallels.com, akpm@linux-foundation.org
Subject: Re: [PATCH 1/6] mm, oom: do not loop over all tasks if there are no external tasks sharing mm
Date: Fri, 27 May 2016 19:15:44 +0900 [thread overview]
Message-ID: <201605271915.FHC65667.SMFHOFOQOLtFJV@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20160527080319.GD27686@dhcp22.suse.cz>
Michal Hocko wrote:
> +bool task_has_external_users(struct task_struct *p)
> +{
> + struct mm_struct *mm = NULL;
> + struct task_struct *t;
> + int active_threads = 0;
> + bool ret = true; /* be pessimistic */
> +
> + rcu_read_lock();
> + for_each_thread(p, t) {
> + task_lock(t);
> + if (likely(t->mm)) {
> + active_threads++;
> + if (!mm) {
> + mm = t->mm;
> + atomic_inc(&mm->mm_count);
> + }
> + }
> + task_unlock(t);
> + }
> + rcu_read_unlock();
> +
I don't like this. We might sleep here long enough to change mm_users.
> + if (mm) {
> + if (atomic_read(&mm->mm_users) <= active_threads)
> + ret = false;
> + mmdrop(mm);
> + }
> + return ret;
> +}
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next prev parent reply other threads:[~2016-05-27 11:55 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-26 12:40 [PATCH 0/5] Handle oom bypass more gracefully Michal Hocko
2016-05-26 12:40 ` [PATCH 1/6] mm, oom: do not loop over all tasks if there are no external tasks sharing mm Michal Hocko
2016-05-26 14:30 ` Tetsuo Handa
2016-05-26 14:59 ` Michal Hocko
2016-05-26 15:25 ` [PATCH 1/6] mm, oom: do not loop over all tasks if there are noexternal " Tetsuo Handa
2016-05-26 15:35 ` Michal Hocko
2016-05-26 16:14 ` [PATCH 1/6] mm, oom: do not loop over all tasks if there are no external " Tetsuo Handa
2016-05-27 6:45 ` Michal Hocko
2016-05-27 7:15 ` Michal Hocko
2016-05-27 8:03 ` Michal Hocko
2016-05-27 10:15 ` Tetsuo Handa [this message]
2016-05-26 12:40 ` [PATCH 2/6] proc, oom_adj: extract oom_score_adj setting into a helper Michal Hocko
2016-05-26 12:40 ` [PATCH 3/6] mm, oom_adj: make sure processes sharing mm have same view of oom_score_adj Michal Hocko
2016-05-27 11:18 ` Michal Hocko
2016-05-27 16:18 ` Vladimir Davydov
2016-05-30 7:07 ` Michal Hocko
2016-05-30 8:47 ` Vladimir Davydov
2016-05-30 9:39 ` Michal Hocko
2016-05-30 10:26 ` Vladimir Davydov
2016-05-30 11:11 ` Michal Hocko
2016-05-30 12:19 ` Vladimir Davydov
2016-05-30 12:28 ` Michal Hocko
2016-05-26 12:40 ` [PATCH 4/6] mm, oom: skip over vforked tasks Michal Hocko
2016-05-27 16:48 ` Vladimir Davydov
2016-05-30 7:13 ` Michal Hocko
2016-05-30 9:52 ` Michal Hocko
2016-05-30 10:40 ` Vladimir Davydov
2016-05-30 10:53 ` Michal Hocko
2016-05-30 12:03 ` Michal Hocko
2016-05-26 12:40 ` [PATCH 5/6] mm, oom: kill all tasks sharing the mm Michal Hocko
2016-05-26 12:40 ` [PATCH 6/6] mm, oom: fortify task_will_free_mem Michal Hocko
[not found] ` <201605262311.FFF64092.FFQVtOLOOMJSFH@I-love.SAKURA.ne.jp>
[not found] ` <20160526142317.GC23675@dhcp22.suse.cz>
2016-05-26 14:41 ` Tetsuo Handa
2016-05-26 14:56 ` Michal Hocko
2016-05-27 11:07 ` Michal Hocko
2016-05-27 16:00 ` [PATCH 0/5] Handle oom bypass more gracefully Michal Hocko
2016-05-28 14:04 ` Tetsuo Handa
2016-05-30 7:21 ` Michal Hocko
2016-05-30 11:10 ` Tetsuo Handa
2016-05-30 11:35 ` Michal Hocko
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