mprotect(2) clears the flag for whole page which causes program crash.

[Jung-uk Kim]

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