linux-kernel - Re: [PATCH 0/1] turn mm->exe_file into mm->exe

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Message-ID: <20120305182522.GD12341@moon>
Date:	Mon, 5 Mar 2012 22:25:22 +0400
From:	Cyrill Gorcunov <gorcunov@...nvz.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Matt Helsley <matthltc@...ibm.com>,
	Alexey Dobriyan <adobriyan@...il.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Kees Cook <keescook@...omium.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/1] turn mm->exe_file into mm->exe_path

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
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