linux-kernel - Re: [RFC v4 0/3] Support volatile for anonymous range

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Message-ID: <50D0B5A2.2010707@fb.com>
Date:	Tue, 18 Dec 2012 10:27:46 -0800
From:	Arun Sharma <asharma@...com>
To:	Minchan Kim <minchan@...nel.org>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
	Michael Kerrisk <mtk.manpages@...il.com>, <sanjay@...gle.com>,
	Paul Turner <pjt@...gle.com>,
	David Rientjes <rientjes@...gle.com>,
	John Stultz <john.stultz@...aro.org>,
	Christoph Lameter <cl@...ux.com>,
	Android Kernel Team <kernel-team@...roid.com>,
	Robert Love <rlove@...gle.com>, Mel Gorman <mel@....ul.ie>,
	Hugh Dickins <hughd@...gle.com>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Rik van Riel <riel@...hat.com>,
	Dave Chinner <david@...morbit.com>, Neil Brown <neilb@...e.de>,
	Mike Hommey <mh@...ndium.org>, Taras Glek <tglek@...illa.com>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [RFC v4 0/3] Support volatile for anonymous range

On 12/17/12 10:47 PM, Minchan Kim wrote:

> I hope more inputs from user-space allocator people and test patch
> with their allocator because it might need design change of arena
> management for getting real vaule.

jemalloc knows how to handle MADV_FREE on platforms that support it. 
This looks similar (we'll need a SIGBUS handler that does the right 
thing = zero the page + mark it as non-volatile in the common case).

All of this of course assumes that apps madvise the kernel through APIs 
exposed by the malloc implementation - not via a raw syscall.

In other words, some new user space code needs to be written to test 
this out fully. Sounds feasible though.

  -Arun
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