linux-kernel - Re: [PATCH] mm: rcu-protected get_mm_exe

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Message-ID: <5507023B.4090905@yandex-team.ru>
Date:	Mon, 16 Mar 2015 19:18:03 +0300
From:	Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:	Davidlohr Bueso <dave@...olabs.net>,
	Oleg Nesterov <oleg@...hat.com>
CC:	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] mm: rcu-protected get_mm_exe_file()

On 16.03.2015 17:50, Davidlohr Bueso wrote:
> On Mon, 2015-03-16 at 15:07 +0100, Oleg Nesterov wrote:
>> 	3. and we can remove down_write(mmap_sem) from prctl paths.
>>
>> 	   Actually we can do this even without xchg() above, but we might
>> 	   want to kill MMF_EXE_FILE_CHANGED and test_and_set_bit() check.
>
> Yeah I was waiting for security folks input about this, otherwise this
> still doesn't do it for me as we still have to deal with mmap_sem.
>

Why? mm->flags are updated atomically. mmap_sem isn't required here.

-- 
Konstantin
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