On Fri 10-08-12 20:07:12, Hillf Danton wrote: > On Fri, Aug 10, 2012 at 5:48 PM, Michal Hocko <mhocko@xxxxxxx> wrote: > > On Fri 03-08-12 15:32:35, Michal Hocko wrote: > >> On Fri 03-08-12 20:56:45, Hillf Danton wrote: > >> > The computation of page offset index is open coded, and incorrect, to > >> > be used in scanning prio tree, as huge page offset is required, and is > >> > fixed with the well defined routine. > >> > >> I guess that nobody reported this because if someone really wants to > >> share he will use aligned address for mmap/shmat and so the index is 0. > >> Anyway it is worth fixing. Thanks for pointing out! > > > > I have looked at the code again and I don't think there is any problem > > at all. vma_prio_tree_foreach understands page units so it will find > > appropriate svmas. > > Or am I missing something? > > Well, what if another case of vma_prio_tree_foreach used by hugetlb > is correct? I guess you mean unmap_ref_private and that has been changed by you (0c176d5 mm: hugetlb: fix pgoff computation when unmapping page from vma)... I was wrong at that time when giving my Reviewed-by. The patch didn't break anything because you still find all relevant vmas because vma_hugecache_offset just provides a smaller index which is still within boundaries. I think that 0c176d52 should be reverted because we do not have to refer to the head page in this case and as we can see it causes confusion. > > Hillf -- Michal Hocko SUSE Labs -- 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>