On Tue, Sep 16, 2014 at 05:07:18PM -0700, Hugh Dickins wrote: > On the page migration issue: it's not quite as straightforward as > Christoph suggests. He and I agree completely that mlocked pages > should be migratable, but some real-time-minded people disagree: > so normal compaction is still forbidden to migrate mlocked pages in > the vanilla kernel (though we in Google patch that prohibition out). > So pinning by refcount is no worse for compaction than mlocking, > in the vanilla kernel. These realtime people are fully aware of this -- they should be at least, I've been telling them for years. Also, they would be very happy with means to actually pin pages -- as per the patches Christoph referred to. The advantage of also having mpin() and co is that we can migrate the memory into non-movable blocks before returning etc. In any case, I think we can (and should) change the behaviour of mlock to be migratable (possibly with an easy way to revert in -rt for migratory purposes until we get mpin sorted). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>