Re: [PATCH] Enable mprotect on huge pages

[David Gibson <david@gibson.dropbear.id.au>]

On Tue, Feb 28, 2006 at 11:23:54AM +0800, Zhang, Yanmin wrote:
> On Tue, 2006-02-28 at 09:34, Andrew Morton wrote:
> > "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> wrote:
> > >
> > > > > > > 2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb
> > >  > > > > mprotect. My patch against 2.6.16-rc3 enables this capability.
> > > 
> > >  Based on David's comments, I worked out a new patch against 2.6.16-rc4.
> > >  Thank David.
> > > 
> > 
> > Please always send an updated changelog when sending an updated patch. 
> > Otherwise I have to go trolling back through the email thread to find it,
> > then work out what needs to be changed.
> Thanks for your kind reminder. I would do so next time.
> 
> > 
> > > 
> > >  I tested it on i386/x86_64/ia64. Who could help test it on other
> > >  platforms, such like PPC64?
> > 
> > I can do that - please send me your test app?
> I attach a test case. It will create directory /mnt/hugepages and delete it
> after testing automatically.
> 
> To run it by user root:
> #gcc -o mprotect_testcase mprotect_testcase.c
> #echo "5">/proc/sys/vm/nr_hugepages
> #./mprotect_testcase
> 
> You could use gdb to step it to see the changing of the process vma maps.

I've just added a simpler testcase than this one to the libhugetlbfs
testsuite.  Both R->RW and RW->R transitions appear to work (I haven't
tested EXEC transitions yet, that's hairier).

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson
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