Re: [PATCH 4.4 040/103] pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes

From	Ben Hutchings <ben.hutchings@codethink.co.uk>
Newsgroups	linux.kernel
Subject	Re: [PATCH 4.4 040/103] pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes
Date	2017-06-01 14:00 +0200
Message-ID	<tNwVI-24Q-15@gated-at.bofh.it> (permalink)
References	<tKoKZ-8pv-3@gated-at.bofh.it> <tKp4n-7w-45@gated-at.bofh.it>
Organization	Codethink Ltd.

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On Tue, 2017-05-23 at 22:09 +0200, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Eric W. Biederman <ebiederm@xmission.com>
> 
> commit b9a985db98961ae1ba0be169f19df1c567e4ffe0 upstream.
> 
> 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.
[...]

This seems to rely on the task not actually being signallable due to the
PF_EXITING flag.  Using TASK_IDLE would be clearer (though less
backport-able).

Ben.

-- 
Ben Hutchings
Software Developer, Codethink Ltd.

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Re: [PATCH 4.4 040/103] pid_ns: Sleep in TASK_INTERRUPTIBLE in  zap_pid_ns_processes Ben Hutchings <ben.hutchings@codethink.co.uk> - 2017-06-01 14:00 +0200
  Re: [PATCH 4.4 040/103] pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes ebiederm@xmission.com (Eric W. Biederman) - 2017-06-01 16:00 +0200

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