On Thu, Jul 23, 2020 at 4:02 AM Yauheni Kaliuta <yauheni.kaliuta@xxxxxxxxxx> wrote: > > Hi! > > I have a question about the part of the test: > [...] > > In my configuration the first mapping > > /* map all but last page: pages 1-3 mapped */ > tmp1 = mmap(NULL, 3 * page_size, PROT_READ, MAP_SHARED, > data_map_fd, 0); > > > maps the area to the 3 pages right before the TLS page. > I find it's pretty ok. Hm... I never ran into this problem. The point here is to be able to re-mmap partial ranges. One way would be to re-write all those manipulations to start with a full range map, and then do partial un-mmaps/re-mmaps, eventually just re-mmaping everything back. I think that would work, right, as long as we never unmmap the last page? Do you mind trying to fix the test in such a fashion? > > But then the 4 page mapping > > /* re-map all 4 pages */ > tmp2 = mmap(tmp1, 4 * page_size, PROT_READ, MAP_SHARED | MAP_FIXED, > data_map_fd, 0); > > > since it has MAP_FIXED flag, unmaps TLS and maps the former TLS > address BPF map. > > Which is again exactly the behaviour of MAP_FIXED, but it breaks > the test. > > Using MAP_FIXED_NOREPLACE fails the check: > > CHECK(tmp1 != tmp2, "adv_mmap6", "tmp1: %p, tmp2: %p\n", tmp1, tmp2); > > as expected. > > > Should the test be modified to be a bit more relaxed? Since the > kernel behaviour looks correct or I'm missing something? > > > PS: BTW, the previous data_map mapping left unmmaped. Is it expected? Not intentional, the idea is that each test exits with a clean state. > > -- > WBR, > Yauheni Kaliuta >
