linux-kernel - Re: Change in functionality of futex() system call.

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Date:	Mon, 06 Jun 2011 18:22:29 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	David Oliver <david@...advisors.com>, linux-kernel@...r.kernel.org,
	Shawn Bohrer <sbohrer@...advisors.com>,
	Zachary Vonler <zvonler@...advisors.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Hugh Dickins <hughd@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Darren Hart <dvhart@...ux.intel.com>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: Change in functionality of futex() system call.

Le lundi 06 juin 2011 à 18:16 +0200, Peter Zijlstra a écrit :

> Hmm, wouldn't that still be susceptible to the zero-page thing if: we
> create a writable private file map of a sparse file, touch a page and
> then remap the thing RO?
> 
> 
> 

Also I am not sure how MAP_PRIVATE could be affected. If we still try a
RW gup()... It will allocate a page for us, instead of still pointing to
shared one.

On previous kernel, the application using read-only mapping could use
MAP_PRIVATE or MAP_SHARED with same 'behavior'


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