linux-kernel - Re: [PATCH 6/7] mm: kill vma flag VM

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Message-ID: <4F79755B.3030703@openvz.org>
Date:	Mon, 02 Apr 2012 13:46:03 +0400
From:	Konstantin Khlebnikov <khlebnikov@...nvz.org>
To:	Cyrill Gorcunov <gorcunov@...nvz.org>
CC:	Oleg Nesterov <oleg@...hat.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Eric Paris <eparis@...hat.com>,
	"linux-security-module@...r.kernel.org" 
	<linux-security-module@...r.kernel.org>,
	"oprofile-list@...ts.sf.net" <oprofile-list@...ts.sf.net>,
	Matt Helsley <matthltc@...ibm.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH 6/7] mm: kill vma flag VM_EXECUTABLE

Cyrill Gorcunov wrote:
> On Sat, Mar 31, 2012 at 10:13:24PM +0200, Oleg Nesterov wrote:
>>
>> Add Cyrill. This conflicts with
>> c-r-prctl-add-ability-to-set-new-mm_struct-exe_file.patch in -mm.
>
> Thanks for CC'ing, Oleg. I think if thise series go in it won't
> be a problem to update my patch accordingly.

In this patch I leave mm->exe_file lockless.
After exec/fork we can change it only for current task and only if mm->mm_users == 1.

something like this:

task_lock(current);
if (atomic_read(&current->mm->mm_users) == 1)
	set_mm_exe_file(current->mm, new_file);
else
	ret = -EBUSY;
task_unlock(current);

task_lock() protect this code against get_task_mm()
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