On Fri, 27 Aug 2010, Hugh Dickins wrote: > Eh? My solution was a second page_mapped(page) test i.e. testing an atomic. Argh. Right. Looked like a global to me. Did not see the earlier local def. If you still use a pointer then what does insure that the root pointer was not changed after the ACCESS_ONCE? The free semantics of an anon_vma? Since there is no lock taken before the mapped check none of the earlier reads from the anon vma structure nor the page mapped check necessarily reflect a single state of the anon_vma. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>