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Re: [REVIEW][PATCH] pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes

From Guenter Roeck <linux@roeck-us.net>
Newsgroups linux.kernel
Subject Re: [REVIEW][PATCH] pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes
Date 2017-05-12 21:40 +0200
Message-ID <tGozU-Ud-7@gated-at.bofh.it> (permalink)
References (5 earlier) <tGfdg-2rg-11@gated-at.bofh.it> <tGiXv-5aV-13@gated-at.bofh.it> <tGm55-7o1-37@gated-at.bofh.it> <tGmHM-7YH-9@gated-at.bofh.it> <tGnaO-8qN-15@gated-at.bofh.it>
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On Fri, May 12, 2017 at 12:55:22PM -0500, Eric W. Biederman wrote:
> Date: Thu, 11 May 2017 18:21:01 -0500
> 
> The code can potentially sleep for an indefinite amount of time in
> zap_pid_ns_processes triggering the hung task timeout, and increasing
> the system average.  This is undesirable.  Sleep with a task state of
> TASK_INTERRUPTIBLE instead of TASK_UNINTERRUPTIBLE to remove these
> undesirable side effects.
> 
> Apparently under heavy load this has been allowing Chrome to trigger
> the hung time task timeout error and cause ChromeOS to reboot.
> 
> Reported-by: Vovo Yang <vovoy@google.com>
> Reported-by: Guenter Roeck <linux@roeck-us.net>

Tested-by: Guenter Roeck <linux@roeck-us.net>

> Fixes: 6347e9009104 ("pidns: guarantee that the pidns init will be the last pidns process reaped")
> Cc: stable@vger.kernel.org
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
> 
> This is what I have queued up posting so it is public knowledge and so
> that if anyone can see a flaw it can get fixed.
> 
>  kernel/pid_namespace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
> index de461aa0bf9a..6e51b8820495 100644
> --- a/kernel/pid_namespace.c
> +++ b/kernel/pid_namespace.c
> @@ -277,7 +277,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
>  	 * if reparented.
>  	 */
>  	for (;;) {
> -		set_current_state(TASK_UNINTERRUPTIBLE);
> +		set_current_state(TASK_INTERRUPTIBLE);
>  		if (pid_ns->nr_hashed == init_pids)
>  			break;
>  		schedule();
> -- 
> 2.10.1
> 

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Thread

Re: Threads stuck in zap_pid_ns_processes() Guenter Roeck <linux@roeck-us.net> - 2017-05-11 22:30 +0200
  Re: Threads stuck in zap_pid_ns_processes() ebiederm@xmission.com (Eric W. Biederman) - 2017-05-11 23:40 +0200
    Re: Threads stuck in zap_pid_ns_processes() Guenter Roeck <linux@roeck-us.net> - 2017-05-12 00:50 +0200
      Re: Threads stuck in zap_pid_ns_processes() ebiederm@xmission.com (Eric W. Biederman) - 2017-05-12 01:30 +0200
        Re: Threads stuck in zap_pid_ns_processes() Vovo Yang <vovoy@google.com> - 2017-05-12 11:40 +0200
          Re: Threads stuck in zap_pid_ns_processes() ebiederm@xmission.com (Eric W. Biederman) - 2017-05-12 15:40 +0200
            Re: Threads stuck in zap_pid_ns_processes() Guenter Roeck <linux@roeck-us.net> - 2017-05-12 19:00 +0200
              Re: Threads stuck in zap_pid_ns_processes() ebiederm@xmission.com (Eric W. Biederman) - 2017-05-12 19:40 +0200
                [REVIEW][PATCH] pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes ebiederm@xmission.com (Eric W. Biederman) - 2017-05-12 20:10 +0200
                Re: [REVIEW][PATCH] pid_ns: Sleep in TASK_INTERRUPTIBLE in  zap_pid_ns_processes Guenter Roeck <linux@roeck-us.net> - 2017-05-12 21:40 +0200
                Re: Threads stuck in zap_pid_ns_processes() Guenter Roeck <linux@roeck-us.net> - 2017-05-12 21:50 +0200
                Re: Threads stuck in zap_pid_ns_processes() ebiederm@xmission.com (Eric W. Biederman) - 2017-05-12 22:20 +0200
                Re: Threads stuck in zap_pid_ns_processes() Guenter Roeck <linux@roeck-us.net> - 2017-05-13 16:40 +0200
                Re: Threads stuck in zap_pid_ns_processes() ebiederm@xmission.com (Eric W. Biederman) - 2017-05-13 20:30 +0200
      Re: Threads stuck in zap_pid_ns_processes() ebiederm@xmission.com (Eric W. Biederman) - 2017-05-12 05:50 +0200

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