Re: [PATCH V5 5/7] mm: mmap: Add mmap flag to request VM_LOCKONFAULT

On Fri, Jul 24, 2015 at 05:28:43PM -0400, Eric B Munson wrote:

The cost of faulting in all memory to be locked can be very high when
working with large mappings.  If only portions of the mapping will be
used this can incur a high penalty for locking.

Now that we have the new VMA flag for the locked but not present state,
expose it as an mmap option like MAP_LOCKED -> VM_LOCKED.

As I mentioned before, I don't think this interface is justified.

MAP_LOCKED has known issues[1]. The MAP_LOCKED problem is not necessary
affects MAP_LOCKONFAULT, but still.

Let's not add new interface unless it's demonstrably useful.

[1] http://lkml.kernel.org/g/20150114095019.GC4706@dhcp22.suse.cz

-- 
 Kirill A. Shutemov