Commit 0db282ba authored by Peter Collingbourne's avatar Peter Collingbourne Committed by Linus Torvalds

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/Icac91064fcd923f77a83e8e133f8631c5b8fc241
Fixes: c47174fc ("userfaultfd: selftest")
Co-developed-by: default avatarLokesh Gidra <lokeshgidra@google.com>
Signed-off-by: default avatarLokesh Gidra <lokeshgidra@google.com>
Signed-off-by: default avatarPeter Collingbourne <pcc@google.com>
Reviewed-by: default avatarCatalin 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e71e2ace
......@@ -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)
......
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