From: Peter Collingbourne pcc@google.com 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@google.com Link: https://linux-review.googlesource.com/id/Icac91064fcd923f77a83e8e133f8631c5b... Fixes: c47174fc362a ("userfaultfd: selftest") Co-developed-by: Lokesh Gidra lokeshgidra@google.com Signed-off-by: Lokesh Gidra lokeshgidra@google.com Signed-off-by: Peter Collingbourne pcc@google.com Reviewed-by: Catalin Marinas catalin.marinas@arm.com Cc: Vincenzo Frascino vincenzo.frascino@arm.com Cc: Dave Martin Dave.Martin@arm.com Cc: Will Deacon will@kernel.org Cc: Andrea Arcangeli aarcange@redhat.com Cc: Alistair Delva adelva@google.com Cc: William McVicker willmcvicker@google.com Cc: Evgenii Stepanov eugenis@google.com Cc: Mitch Phillips mitchp@google.com Cc: Andrey Konovalov andreyknvl@gmail.com Cc: stable@vger.kernel.org [5.4] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
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) _