From: Peter Collingbourne <pcc@xxxxxxxxxx> Subject: selftest: use mmap instead of posix_memalign to allocate memory This test passes pointers obtained from anon_allocate_area to the userfaultfd and mremap APIs. This causes a problem if the system allocator returns tagged pointers because with the tagged address ABI the kernel rejects tagged addresses passed to these APIs, which would end up causing the test to fail. To make this test compatible with such system allocators, stop using the system allocator to allocate memory in anon_allocate_area, and instead just use mmap. Link: https://lkml.kernel.org/r/20210714195437.118982-3-pcc@xxxxxxxxxx Link: https://linux-review.googlesource.com/id/Icac91064fcd923f77a83e8e133f8631c5b8fc241 Fixes: c47174fc362a ("userfaultfd: selftest") Co-developed-by: Lokesh Gidra <lokeshgidra@xxxxxxxxxx> Signed-off-by: Lokesh Gidra <lokeshgidra@xxxxxxxxxx> Signed-off-by: Peter Collingbourne <pcc@xxxxxxxxxx> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> Cc: Dave Martin <Dave.Martin@xxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Alistair Delva <adelva@xxxxxxxxxx> Cc: William McVicker <willmcvicker@xxxxxxxxxx> Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx> Cc: Mitch Phillips <mitchp@xxxxxxxxxx> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [5.4] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/vm/userfaultfd.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/tools/testing/selftests/vm/userfaultfd.c~selftest-use-mmap-instead-of-posix_memalign-to-allocate-memory +++ a/tools/testing/selftests/vm/userfaultfd.c @@ -210,8 +210,10 @@ static void anon_release_pages(char *rel static void anon_allocate_area(void **alloc_area) { - if (posix_memalign(alloc_area, page_size, nr_pages * page_size)) - err("posix_memalign() failed"); + *alloc_area = mmap(NULL, nr_pages * page_size, PROT_READ | PROT_WRITE, + MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); + if (*alloc_area == MAP_FAILED) + err("mmap of anonymous memory failed"); } static void noop_alias_mapping(__u64 *start, size_t len, unsigned long offset) _
