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From: Oleg Nesterov <oleg@redhat.com>
To: Sameer Nanda <snanda@chromium.org>
Cc: akpm@linux-foundation.org, mhocko@suse.cz, rientjes@google.com,
	hannes@cmpxchg.org, rusty@rustcorp.com.au, semenzato@google.com,
	murzin.v@gmail.com, dserrg@gmail.com, msb@chromium.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mm, oom: Fix race when selecting process to kill
Date: Fri, 8 Nov 2013 19:45:15 +0100	[thread overview]
Message-ID: <20131108184515.GA11555@redhat.com> (raw)
In-Reply-To: <1383934035-933-1-git-send-email-snanda@chromium.org>

Sorry.

I didn't have time to answer other emails, will try to do later.

And yes, yes, while_each_thread() should be fixed, still on my
TODO list... But just in case, whatever we do with while_each_thread()
we should also fix some users.

Until then,

On 11/08, Sameer Nanda wrote:
>
> @@ -412,13 +412,16 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
>  	static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
>  					      DEFAULT_RATELIMIT_BURST);
>
> +	read_lock(&tasklist_lock);
> +
>  	/*
>  	 * If the task is already exiting, don't alarm the sysadmin or kill
>  	 * its children or threads, just set TIF_MEMDIE so it can die quickly
>  	 */
> -	if (p->flags & PF_EXITING) {
> +	if (p->flags & PF_EXITING || !pid_alive(p)) {

OK.

> -	read_lock(&tasklist_lock);

But you should also move read_unlock_down(), at least after
find_lock_task_mm().

And of course, this doesn't fix other users in oom_kill.c.

Oleg.


WARNING: multiple messages have this Message-ID (diff)
From: Oleg Nesterov <oleg@redhat.com>
To: Sameer Nanda <snanda@chromium.org>
Cc: akpm@linux-foundation.org, mhocko@suse.cz, rientjes@google.com,
	hannes@cmpxchg.org, rusty@rustcorp.com.au, semenzato@google.com,
	murzin.v@gmail.com, dserrg@gmail.com, msb@chromium.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mm, oom: Fix race when selecting process to kill
Date: Fri, 8 Nov 2013 19:45:15 +0100	[thread overview]
Message-ID: <20131108184515.GA11555@redhat.com> (raw)
In-Reply-To: <1383934035-933-1-git-send-email-snanda@chromium.org>

Sorry.

I didn't have time to answer other emails, will try to do later.

And yes, yes, while_each_thread() should be fixed, still on my
TODO list... But just in case, whatever we do with while_each_thread()
we should also fix some users.

Until then,

On 11/08, Sameer Nanda wrote:
>
> @@ -412,13 +412,16 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
>  	static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
>  					      DEFAULT_RATELIMIT_BURST);
>
> +	read_lock(&tasklist_lock);
> +
>  	/*
>  	 * If the task is already exiting, don't alarm the sysadmin or kill
>  	 * its children or threads, just set TIF_MEMDIE so it can die quickly
>  	 */
> -	if (p->flags & PF_EXITING) {
> +	if (p->flags & PF_EXITING || !pid_alive(p)) {

OK.

> -	read_lock(&tasklist_lock);

But you should also move read_unlock_down(), at least after
find_lock_task_mm().

And of course, this doesn't fix other users in oom_kill.c.

Oleg.

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  reply	other threads:[~2013-11-08 18:43 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-05 23:26 [PATCH] mm, oom: Fix race when selecting process to kill Sameer Nanda
2013-11-05 23:26 ` Sameer Nanda
2013-11-06  1:18 ` David Rientjes
2013-11-06  1:18   ` David Rientjes
2013-11-06  1:25   ` Luigi Semenzato
2013-11-06  1:25     ` Luigi Semenzato
2013-11-06  1:27     ` David Rientjes
2013-11-06  1:27       ` David Rientjes
2013-11-06  3:00       ` Vladimir Murzin
2013-11-06  3:00         ` Vladimir Murzin
2013-11-06  3:04       ` Sameer Nanda
2013-11-06  4:45         ` Luigi Semenzato
2013-11-06  4:45           ` Luigi Semenzato
2013-11-06  7:17           ` Luigi Semenzato
2013-11-06  7:17             ` Luigi Semenzato
2013-11-06 16:58             ` Sameer Nanda
2013-11-06 16:58               ` Sameer Nanda
2013-11-07  0:35               ` David Rientjes
2013-11-07  0:35                 ` David Rientjes
2013-11-07 19:34                 ` Sameer Nanda
2013-11-07 19:34                   ` Sameer Nanda
2013-11-08 18:07                 ` [PATCH v2] " Sameer Nanda
2013-11-08 18:07                   ` Sameer Nanda
2013-11-08 18:45                   ` Oleg Nesterov [this message]
2013-11-08 18:45                     ` Oleg Nesterov
2013-11-08 19:49                     ` [PATCH v3] " Sameer Nanda
2013-11-08 19:49                       ` Sameer Nanda
2013-11-09 15:16                       ` Oleg Nesterov
2013-11-09 15:16                         ` Oleg Nesterov
2013-11-11 23:15                         ` Sameer Nanda
2013-11-12  0:21                         ` [PATCH v4] " Sameer Nanda
2013-11-12  0:21                           ` Sameer Nanda
2013-11-12 15:13                           ` Michal Hocko
2013-11-12 15:13                             ` Michal Hocko
2013-11-12 20:01                           ` Oleg Nesterov
2013-11-12 20:01                             ` Oleg Nesterov
2013-11-12 20:08                             ` Sameer Nanda
2013-11-12 20:08                               ` Sameer Nanda
2013-11-12 20:23                               ` [PATCH v5] " Sameer Nanda
2013-11-12 20:23                                 ` Sameer Nanda
2013-11-13  2:33                                 ` David Rientjes
2013-11-13  2:33                                   ` David Rientjes
2013-11-13 16:46                                   ` Sameer Nanda
2013-11-13 16:46                                     ` Sameer Nanda
2013-11-13 17:18                                     ` [PATCH v6] " Sameer Nanda
2013-11-13 17:18                                       ` Sameer Nanda
2013-11-13 17:29                                       ` Oleg Nesterov
2013-11-13 17:29                                         ` Oleg Nesterov
2013-11-14 13:43                                       ` dserrg
2013-11-14 17:03                                         ` Sameer Nanda
2013-11-14 17:03                                           ` Sameer Nanda

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