linux-kernel - Re: [PATCH 1/9] exec_path 1/9: introduce ->exec

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Message-ID: <alpine.LFD.2.01.0906050808551.6847@localhost.localdomain>
Date:	Fri, 5 Jun 2009 08:10:50 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Christoph Hellwig <hch@...radead.org>
cc:	Alexey Dobriyan <adobriyan@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Matt Helsley <matthltc@...ibm.com>, xemul@...allels.com,
	containers@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org, dave@...ux.vnet.ibm.com,
	mingo@...e.hu, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 1/9] exec_path 1/9: introduce ->exec_path and switch
 /proc/*/exe



On Fri, 5 Jun 2009, Christoph Hellwig wrote:
>
> On Thu, Jun 04, 2009 at 03:04:22AM +0400, Alexey Dobriyan wrote:
> > ->exec_path is copied on clone(2) and put at do_exit() time.
> > 
> > ->exec_path is going to replace struct mm_struct::exe_file et al
> > and allows to remove VM_EXECUTABLE flag while keeping readlink("/proc/*/exe")
> > without loop over all VMAs.
> 
> Why don't you leave it in mm_struct?  That'll avoid having to mess with
> it in clone, and given that exec always replaces the whole VM it's a
> more natural fit anyway.

Oh, I didn't even notice that, because I just assumed it was in mm_struct 
already due to the earlier discussion.

So I concur with Christoph - that field should be in the mm_struct. The 
executable is a "mapping" issue, and goes along with task->mm, and should 
be there, not in task_struct.

So it should be copied at fork() time when you do the dup_mm(), not 
anywhere else.

		Linus
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