Re: [PATCH][RFC] add MAP_UNLOCKED mmap flag

[Gleb Natapov <gleb@redhat.com>]

On Tue, Oct 06, 2009 at 12:49:52PM +0200, Arnd Bergmann wrote:
> On Tuesday 06 October 2009, Gleb Natapov wrote:
> > If application does mlockall(MCL_FUTURE) it is no longer possible to
> > mmap file bigger than main memory or allocate big area of anonymous
> > memory. Sometimes it is desirable to lock everything related to program
> > execution into memory, but still be able to mmap big file or allocate
> > huge amount of memory and allow OS to swap them on demand. MAP_UNLOCKED
> > allows to do that.
> > 
> > Signed-off-by: Gleb Natapov <gleb@redhat.com>
> > diff --git a/include/asm-generic/mman.h b/include/asm-generic/mman.h
> > index 32c8bd6..0ab4c74 100644
> > --- a/include/asm-generic/mman.h
> > +++ b/include/asm-generic/mman.h
> > @@ -12,6 +12,7 @@
> >  #define MAP_NONBLOCK   0x10000         /* do not block on IO */
> >  #define MAP_STACK      0x20000         /* give out an address that is best suited for process/thread stacks */
> >  #define MAP_HUGETLB    0x40000         /* create a huge page mapping */
> > +#define MAP_UNLOKED    0x80000         /* pages are unlocked */
> >  
> >  #define MCL_CURRENT    1               /* lock all current mappings */
> >  #define MCL_FUTURE     2               /* lock all future mappings */
> 
> Not all architectures use asm-generic/mman.h, so you have to change
> the other architectures separately if you add a flag.
> 
Ah, good to know. Thanks.

--
			Gleb.

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