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Subject: Re: [PATCH 2/3] vfork: make it killable
From: Matt Fleming <matt.fleming@intel.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>,
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        linux-kernel@vger.kernel.org, Pavel Machek <pavel@ucw.cz>
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Date: Fri, 19 Aug 2011 21:33:58 +0100
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On Fri, 2011-08-12 at 19:56 +0200, Oleg Nesterov wrote:
> Make vfork() killable.
> 
> Change do_fork(CLONE_VFORK) to do wait_for_completion_killable().
> If it fails we do not return to the user-mode and never touch ->mm
> shared with our child.
> 
> However, in this case we should clear child->vfork_done before
> return, we use task_lock() in do_fork()->wait_for_vfork_done()
> and complete_vfork_done() to serialize with each other.

It's probably worth updating the comment above task_lock() in
include/linux/sched.h, to say that it is now used to protect
->vfork_done.