From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: ytk.lee@samsung.com, "mhocko@kernel.org" <mhocko@kernel.org>,
"mhocko@suse.com" <mhocko@suse.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm, oom_adj: avoid meaningless loop to find processes sharing mm
Date: Mon, 8 Oct 2018 11:52:09 +0900 [thread overview]
Message-ID: <af7ae9c4-d7f1-69af-58fa-ec6949161f5b@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20181008011931epcms1p82dd01b7e5c067ea99946418bc97de46a@epcms1p8>
On 2018/10/08 10:19, Yong-Taek Lee wrote:
> @@ -1056,6 +1056,7 @@ static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
> struct mm_struct *mm = NULL;
> struct task_struct *task;
> int err = 0;
> + int mm_users = 0;
>
> task = get_proc_task(file_inode(file));
> if (!task)
> @@ -1092,7 +1093,8 @@ static int __set_oom_adj(struct file *file, int oom_adj, bool legacy)
> struct task_struct *p = find_lock_task_mm(task);
>
> if (p) {
> - if (atomic_read(&p->mm->mm_users) > 1) {
> + mm_users = atomic_read(&p->mm->mm_users);
> + if ((mm_users > 1) && (mm_users != get_nr_threads(p))) {
How can this work (even before this patch)? When clone(CLONE_VM without CLONE_THREAD/CLONE_SIGHAND)
is requested, copy_process() calls copy_signal() in order to copy sig->oom_score_adj and
sig->oom_score_adj_min before calling copy_mm() in order to increment mm->mm_users, doesn't it?
Then, we will get two different "struct signal_struct" with different oom_score_adj/oom_score_adj_min
but one "struct mm_struct" shared by two thread groups.
> mm = p->mm;
> atomic_inc(&mm->mm_count);
> }
next prev parent reply other threads:[~2018-10-08 2:53 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20181008011931epcms1p82dd01b7e5c067ea99946418bc97de46a@epcms1p8>
2018-10-08 1:19 ` [PATCH] mm, oom_adj: avoid meaningless loop to find processes sharing mm Yong-Taek Lee
2018-10-08 2:52 ` Tetsuo Handa [this message]
[not found] ` <CGME20181008011931epcms1p82dd01b7e5c067ea99946418bc97de46a@epcms1p5>
2018-10-08 6:14 ` Yong-Taek Lee
2018-10-08 6:22 ` Tetsuo Handa
[not found] ` <CGME20181008011931epcms1p82dd01b7e5c067ea99946418bc97de46a@epcms1p2>
2018-10-08 8:38 ` Yong-Taek Lee
2018-10-08 9:27 ` Tetsuo Handa
2018-10-09 6:35 ` Michal Hocko
2018-10-09 7:50 ` Michal Hocko
2018-10-09 10:00 ` Tetsuo Handa
2018-10-09 11:10 ` Michal Hocko
2018-10-09 12:52 ` Tetsuo Handa
2018-10-09 12:58 ` Michal Hocko
2018-10-09 13:14 ` Tetsuo Handa
2018-10-09 13:26 ` Michal Hocko
2018-10-09 13:51 ` Tetsuo Handa
2018-10-09 14:09 ` Michal Hocko
2018-10-09 8:02 ` Michal Hocko
[not found] <CGME20181005063208epcms1p22959cd2f771ad017996e2b18266791ea@epcms1p2>
[not found] ` <20181005063208epcms1p22959cd2f771ad017996e2b18266791ea@epcms1p2>
2018-10-09 6:23 ` Michal Hocko
2018-10-09 8:03 ` Michal Hocko
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