On 09/08/2015 01:43 PM, Andrea Arcangeli wrote: > Here are some pending updates for userfaultfd mostly to the self test, > the rest are cleanups. I have a potential use case for userfualtfd. So, I started experimenting with the self test code. I replaced the posix_memalign() calls to allocate area_src and area_dst with mmap(). mmap(MAP_PRIVATE | MAP_ANONYMOUS) works as expected. However, mmap(MAP_SHARED | MAP_ANONYMOUS) causes the test to fail without any errros from the userfaultfd APIs. -------------------- running userfaultfd -------------------- nr_pages: 32768, nr_pages_per_cpu: 8192 bounces: 31, mode: rnd racing ver poll, page_nr 31523 wrong count 0 1 I would expect some type of error from the ioctl() that registers the range, or perhaps the poll/copy code? Just curious about the expected behavior. FYI - My use case is for hugetlbfs. I would like a mechanism to catch all new huge page allocations as a result of page faults. I have some very rough code to extend userfualtfd and add the required functionality to hugetlbfs. Still working on it. -- Mike Kravetz -- 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>