On Thu, Aug 03, 2023 at 04:32:08PM +0200, David Hildenbrand wrote: > Let's test whether merging and unmerging in PROT_NONE areas works as > expected. > > Pass a page protection to mmap_and_merge_range(), which will trigger > an mprotect() after writing to the pages, but before enabling merging. > > Make sure that unsharing works as expected, by performing a ptrace write > (using /proc/self/mem) and by setting MADV_UNMERGEABLE. > > Note that this implicitly tests that ptrace writes in an inaccessible > (PROT_NONE) mapping work as expected. > > Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> [...] > +static void test_prot_none(void) > +{ > + const unsigned int size = 2 * MiB; > + char *map; > + int i; > + > + ksft_print_msg("[RUN] %s\n", __func__); > + > + map = mmap_and_merge_range(0x11, size, PROT_NONE, false); > + if (map == MAP_FAILED) > + goto unmap; > + > + /* Store a unique value in each page on one half using ptrace */ > + for (i = 0; i < size / 2; i += pagesize) { > + lseek(mem_fd, (uintptr_t) map + i, SEEK_SET); > + if (write(mem_fd, &i, sizeof(size)) != sizeof(size)) { sizeof(i)? May not matter a huge lot, though.. > + ksft_test_result_fail("ptrace write failed\n"); > + goto unmap; > + } > + } Acked-by: Peter Xu <peterx@xxxxxxxxxx> -- Peter Xu