linux-kernel - Re: + c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm- num_exe_file

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Message-ID: <20120419213204.GP1893@moon>
Date:	Fri, 20 Apr 2012 01:32:04 +0400
From:	Cyrill Gorcunov <gorcunov@...nvz.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	akpm@...ux-foundation.org, khlebnikov@...nvz.org,
	keescook@...omium.org, kosaki.motohiro@...fujitsu.com,
	matthltc@...ibm.com, tj@...nel.org, xemul@...allels.com,
	linux-kernel@...r.kernel.org
Subject: Re: +
 c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm-
 num_exe_file_vmas-removal.patch added to -mm tree

On Thu, Apr 19, 2012 at 11:12:16PM +0200, Oleg Nesterov wrote:
> > Heh :) Oleg, it was actually your idea to make this feature "one-shot".
> 
> Heh, no ;)
> 
> IIRC, I only asked you what do you actually want,
> 
> 	Just one note for the record, prctl_set_mm_exe_file() does
> 
> 		if (mm->num_exe_file_vmas)
> 			return -EBUSY;
> 
> 	We could do
> 
> 		if (mm->exe_file)
> 			return -EBUSY;
> 
> 	This way "because this feature is a special to C/R" becomes
> 	really true. IOW, you can't do PR_SET_MM_EXE_FILE twice.
> 
> 	I am fine either way, just I want to ensure you really want
> 	the current version.
> 
> and only because it was documented as "feature is a special to C/R".

ok, ubedil :)

> > Once exe-file changed to a new value, it can't be changed again. The
> > reason was to bring at least minimum disturbance in sysadmins life.
> 
> You misunderstood. I am not arguing with "one-shot", I do not really
> care.
> 
> My question is: unless I missed something "it can't be changed again"
> is not actually true. A task does PR_SET_MM_EXE_FILE, then it forks
> the new child. The child can do PR_SET_MM_EXE_FILE again. Is this
> by design?

Hmm, not sure, Konstantin?

	Cyrill
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