From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: mhocko@kernel.org
Cc: rientjes@google.com, oleg@redhat.com, vdavydov@parallels.com,
akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
mhocko@suse.com
Subject: Re: [PATCH 6/6] mm, oom: fortify task_will_free_mem
Date: Thu, 26 May 2016 23:11:47 +0900 [thread overview]
Message-ID: <201605262311.FFF64092.FFQVtOLOOMJSFH@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <1464266415-15558-7-git-send-email-mhocko@kernel.org>
Michal Hocko wrote:
> +/*
> + * Checks whether the given task is dying or exiting and likely to
> + * release its address space. This means that all threads and processes
> + * sharing the same mm have to be killed or exiting.
> + */
> +static inline bool task_will_free_mem(struct task_struct *task)
> +{
> + struct mm_struct *mm = NULL;
> + struct task_struct *p;
> +
> + /*
> + * If the process has passed exit_mm we have to skip it because
> + * we have lost a link to other tasks sharing this mm, we do not
> + * have anything to reap and the task might then get stuck waiting
> + * for parent as zombie and we do not want it to hold TIF_MEMDIE
> + */
> + p = find_lock_task_mm(task);
> + if (!p)
> return false;
>
> + if (!__task_will_free_mem(p)) {
> + task_unlock(p);
> + return false;
> + }
> +
> + /*
> + * Check whether there are other processes sharing the mm - they all have
> + * to be killed or exiting.
> + */
> + if (atomic_read(&p->mm->mm_users) > get_nr_threads(p)) {
> + mm = p->mm;
> + /* pin the mm to not get freed and reused */
> + atomic_inc(&mm->mm_count);
> + }
> + task_unlock(p);
> +
> + if (mm) {
> + rcu_read_lock();
> + for_each_process(p) {
> + bool vfork;
> +
> + /*
> + * skip over vforked tasks because they are mostly
> + * independent and will drop the mm soon
> + */
> + task_lock(p);
> + vfork = p->vfork_done;
> + task_unlock(p);
> + if (vfork)
> + continue;
> +
> + if (!__task_will_free_mem(p))
> + break;
> + }
> + rcu_read_unlock();
> + mmdrop(mm);
Did you forget "if (something) return false;" here?
> + }
> +
If task_will_free_mem() == true is always followed by mark_oom_victim()
and wake_oom_reaper(), can we call them from here?
> return true;
> }
next prev parent reply other threads:[~2016-05-26 14:13 UTC|newest]
Thread overview: 41+ 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
2016-05-26 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
2016-05-26 14:11 ` Tetsuo Handa [this message]
2016-05-26 14:23 ` Michal Hocko
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
2016-05-30 13:05 [PATCH 0/6 -v2] " Michal Hocko
2016-05-30 13:05 ` [PATCH 6/6] mm, oom: fortify task_will_free_mem Michal Hocko
2016-05-30 17:35 ` Oleg Nesterov
2016-05-31 7:46 ` Michal Hocko
2016-05-31 22:29 ` Oleg Nesterov
2016-06-01 7:03 ` Michal Hocko
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