From owner-freebsd-hackers@FreeBSD.ORG  Wed Nov 18 19:34:03 2009
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From: Jung-uk Kim <jkim@FreeBSD.org>
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Date: Wed, 18 Nov 2009 14:33:46 -0500
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Cc: Robert Watson <rwatson@freebsd.org>, Manprit Singh <manprits@in.niksun.com>,
	Sharad Chandra <sharadc@in.niksun.com>
Subject: Re: mprotect(2) clears the flag for whole page which causes program
	crash.
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On Wednesday 18 November 2009 01:52 pm, Robert Watson wrote:
> On Tue, 17 Nov 2009, Sharad Chandra wrote:
> > Is it known bug or is there any workaround? How will a userland
> > process make sure that process will not crash as malloc(3) can
> > allocate where ever it get the memory free to use.
>
> mprotect(2) operates on pages, so you'll want to use mmap(2) and
> munmap(2) to allocate and free pages directly rather than
> mallac(3), which manages byte ranges from pages managed using those
> same interfaces.

For example:

http://docs.freebsd.org/cgi/mid.cgi?200911181926.nAIJQHOR081471

Jung-uk Kim