Hi Michal, Michal Hocko <mhocko@xxxxxxxxxx> writes: > On Mon 13-11-17 10:20:06, Michal Hocko wrote: >> [Cc arm and ppc maintainers] > > Hmm, it turned out to be a problem on other architectures as well. > CCing more maintainers. For your reference, we are talking about > http://lkml.kernel.org/r/20171023082608.6167-1-mhocko@xxxxxxxxxx > which has broken architectures which do apply aligning on the mmap > address hint without MAP_FIXED applied. See below my proposed way > around this issue because I belive that the above patch is quite > valuable on its own to be dropped for all archs. I don't really like your solution sorry :) The fact that you've had to patch seven arches seems like a red flag. I think this is a generic problem with MAP_FIXED, which I've heard userspace folks complain about in the past. Currently MAP_FIXED does two things: 1. makes addr not a hint but the required address 2. blasts any existing mapping You want 1) but not 2). So the right solution IMHO would be to add a new mmap flag to request that behaviour, ie. a fixed address but iff there is nothing already mapped there. I don't know the mm code well enough to know if that's hard for some reason, but it *seems* like it should be doable. cheers -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
