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Reply-To: "Hillf Danton" <hillf.zj@alibaba-inc.com>
From: "Hillf Danton" <hillf.zj@alibaba-inc.com>
To: "'Oleg Nesterov'" <oleg@redhat.com>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
        "David Rientjes" <rientjes@google.com>,
        "'Kyle Walker'" <kwalker@redhat.com>,
        "'Michal Hocko'" <mhocko@kernel.org>,
        "linux-kernel" <linux-kernel@vger.kernel.org>
References: <04db01d10192$615ef0c0$241cd240$@alibaba-inc.com>
In-Reply-To: <04db01d10192$615ef0c0$241cd240$@alibaba-inc.com>
Subject: Re: [PATCH -mm v2 2/3] mm/oom_kill: cleanup the "kill sharing same memory" loop
Date: Thu, 08 Oct 2015 14:43:49 +0800
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> 
> Purely cosmetic, but the complex "if" condition looks annoying to me.
> Especially because it is not consistent with OOM_SCORE_ADJ_MIN check
> which adds another if/continue.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> ---
>  mm/oom_kill.c | 18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index b6b8c78..c189ee5 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -583,14 +583,18 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
>  	 * pending fatal signal.
>  	 */
>  	rcu_read_lock();
> -	for_each_process(p)
> -		if (p->mm == mm && !same_thread_group(p, victim) &&
> -		    !(p->flags & PF_KTHREAD)) {
> -			if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
> -				continue;
> +	for_each_process(p) {
> +		if (p->mm != mm)
> +			continue;
> +		if (same_thread_group(p, victim))
> +			continue;
> +		if (unlikely(p->flags & PF_KTHREAD))
> +			continue;

Given the result of "grep -nr PF_KTHREAD linux-next/mm", it looks
a helper function, like current_is_kswapd(), is needed.

int task_is_kthread(struct task_struct *task)

Other than that,
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>

> +		if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
> +			continue;
> 
> -			do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
> -		}
> +		do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
> +	}
>  	rcu_read_unlock();
> 
>  	mmput(mm);
> --
> 2.4.3
> 
>