The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 0db282ba2c12c1515d490d14a1ff696643ab0f1b Mon Sep 17 00:00:00 2001

From: Peter Collingbourne pcc@google.com Date: Fri, 23 Jul 2021 15:50:04 -0700 Subject: [PATCH] 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 Signed-off-by: Linus Torvalds torvalds@linux-foundation.org

diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c index e363bdaff59d..2ea438e6b8b1 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -210,8 +210,10 @@ static void anon_release_pages(char *rel_area)

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)