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Date: Mon, 5 Mar 2012 22:25:22 +0400
From: Cyrill Gorcunov <gorcunov@openvz.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Matt Helsley <matthltc@us.ibm.com>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Kees Cook <keescook@chromium.org>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Pavel Emelyanov <xemul@parallels.com>, Tejun Heo <tj@kernel.org>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/1] turn mm->exe_file into mm->exe_path
Message-ID: <20120305182522.GD12341@moon>
References: <20120305152826.GA12419@redhat.com>
 <20120305170556.GC12341@moon>
 <20120305173314.GA17895@redhat.com>
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On Mon, Mar 05, 2012 at 06:33:14PM +0100, Oleg Nesterov wrote:
> 
> > Not sure where we may use PR_SET_MM_EXE_PATH with NULL to kill
> > num_exe_file_vmas from user space though
> 
> Please see above:
> 
> 	Why do we need mm->num_exe_file_vmas? Afaics it is only needed to
> 	"free" mm->exe_file if the application unmaps all these vmas. Say,
> 	to allow to unmount fs.
> 
> If we remove this counter, the application can't do the final put.
> But if we add PR_SET_MM_EXE_PATH which accepts NULL we solve this
> problem and this works for c/r too.
> 
> Of course, this is orthogonal to the patch I sent.
> 

I see. Thanks, Oleg!

	Cyrill