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From: ijackson@chiark.greenend.org.uk
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg KH <gregkh@suse.de>, Ian Campbell <ijc@hellion.org.uk>,
	linux-kernel@vger.kernel.org, stable@kernel.org,
	stable-review@kernel.org, akpm@linux-foundation.org,
	alan@lxorguk.ukuu.org.uk, Peter Zijlstra <peterz@infradead.org>,
	Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: [RFC] mlock/stack guard interaction fixup
Date: Mon, 23 Aug 2010 16:42:08 +0100	[thread overview]
Message-ID: <19570.38608.79434.179797@chiark.greenend.org.uk> (raw)
In-Reply-To: <AANLkTi=wWcAg8MdWy4O-0au3m6mH+9xWDOKVCJ_x5G_v@mail.gmail.com>

Linus Torvalds writes ("Re: [RFC] mlock/stack guard interaction fixup"):
> Although you do need to have some really odd things going on for any
> of them to make any difference. Notably, you need to do mlock or
> mprotect on the stack segment, which no sane program does.

mlocking the stack is entirely sensible and normal for a real-time
program.  Most such programs use mlockall but there is no particular
reason why a program that has some more specific requirements should
use mlock to lock only a part of the stack.  (Perhaps it has only one
real-time thread?)

Locking, including of the stack, is discussed extensively here:
  http://www.opengroup.org/onlinepubs/9699919799/xrat/V4_xsh_chap02.html
  section "Memory locking functions" subsection "Requirements".

Ian.



  parent reply	other threads:[~2010-08-23 16:01 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-20 23:59 [RFC] mlock/stack guard interaction fixup Linus Torvalds
2010-08-21  0:20 ` Mike Snitzer
2010-08-21  0:54   ` Linus Torvalds
2010-08-21 11:56 ` Ian Campbell
2010-08-21 15:48   ` Linus Torvalds
2010-08-21 16:08     ` Sam Ravnborg
2010-08-23 16:34       ` Tony Luck
2010-08-22  6:57     ` Ian Campbell
2010-08-22  7:33       ` Ian Campbell
2010-08-22  9:55         ` Ian Campbell
2010-08-22 16:43           ` Linus Torvalds
2010-08-22 17:25           ` Greg KH
2010-08-22 18:21             ` Linus Torvalds
2010-08-22 19:04               ` Greg KH
2010-08-23  9:22               ` Peter Zijlstra
2010-08-23 15:42               ` ijackson [this message]
2010-08-23 16:25                 ` Peter Zijlstra
2010-08-23 17:18                   ` Ian Jackson
2010-08-23 17:34                     ` Linus Torvalds
2010-08-23 17:53                       ` Peter Zijlstra
2010-08-23 17:59                       ` Peter Zijlstra
2010-08-23 18:43                         ` Darren Hart
2010-08-23 18:50                       ` Jeremy Fitzhardinge
2010-08-23 19:07                         ` Peter Zijlstra
2010-08-23 19:23                           ` Jeremy Fitzhardinge
2010-08-23 19:26                             ` Peter Zijlstra
2010-08-23 19:54                               ` Jeremy Fitzhardinge
2010-08-24  7:08                                 ` Peter Zijlstra
2010-08-24  7:20                                   ` Peter Zijlstra
2010-08-23 19:03                       ` Ian Campbell
2010-08-23 17:40                     ` Peter Zijlstra
2010-08-23 18:53                     ` Jeremy Fitzhardinge
2010-08-25  8:28             ` [Stable-review] " Stefan Bader
2010-08-23  9:00 ` Peter Zijlstra

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