On Mon, 27 Jul 2015, Kirill A. Shutemov wrote: > 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@xxxxxxxxxxxxxx I understand and should have been more explicit. This patch is still included becuase I have an internal user that wants to see it added. The problem discussed in the thread you point out does not affect MAP_LOCKONFAULT because we do not attempt to populate the region with MAP_LOCKONFAULT. As I told Vlastimil, if this is a hard NAK with the patch I can work with that. Otherwise I prefer it stays.
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