On Tue, Aug 27, 2024 at 10:49:22PM GMT, Charlie Jenkins wrote:
Add a selftest for MAP_BELOW_HINT that maps until it runs out of space below the hint address.
Signed-off-by: Charlie Jenkins charlie@rivosinc.com
tools/testing/selftests/mm/Makefile | 1 + tools/testing/selftests/mm/map_below_hint.c | 29 +++++++++++++++++++++++++++++ 2 files changed, 30 insertions(+)
diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile index cfad627e8d94..4e2de85267b5 100644 --- a/tools/testing/selftests/mm/Makefile +++ b/tools/testing/selftests/mm/Makefile @@ -50,6 +50,7 @@ TEST_GEN_FILES += hugepage-shm TEST_GEN_FILES += hugepage-vmemmap TEST_GEN_FILES += khugepaged TEST_GEN_FILES += madv_populate +TEST_GEN_FILES += map_below_hint TEST_GEN_FILES += map_fixed_noreplace TEST_GEN_FILES += map_hugetlb TEST_GEN_FILES += map_populate diff --git a/tools/testing/selftests/mm/map_below_hint.c b/tools/testing/selftests/mm/map_below_hint.c new file mode 100644 index 000000000000..305274c5af49 --- /dev/null +++ b/tools/testing/selftests/mm/map_below_hint.c @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0 +/*
- Test the MAP_BELOW_HINT mmap flag.
- */
+#include <sys/mman.h> +#include "../kselftest.h"
+#define ADDR 0x1000000UL +#define LENGTH (ADDR / 100)
+#define MAP_BELOW_HINT 0x8000000 /* Not defined in all libc */
+/*
- Map memory with MAP_BELOW_HINT until no memory left. Ensure that all returned
- addresses are below the hint.
- */
+int main(int argc, char **argv) +{
- void *addr;
- do {
addr = mmap((void *)ADDR, LENGTH, MAP_ANONYMOUS, MAP_BELOW_HINT, -1, 0);
How can this be correct? mmap() has parameters:
void *mmap(void addr[.length], size_t length, int prot, int flags, int fd, off_t offset);
You'r setting prot = MAP_ANONYMOUS, flags = MAP_BELOW_HINT...
This surely should be:
mmap(..., PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE | MAP_BELOW_HINT, -1, 0);
- } while (addr == MAP_FAILED && (unsigned long)addr <= ADDR);
How can addr == MAP_FAILED (i.e. ~0) and addr <= ADDR? This will just loop through once...
If you want to make sure you're getting mappings only below the hint until you start getting MAP_FAILED's you'll need to handle this more robustly.
- if (addr != MAP_FAILED && (unsigned long)addr > ADDR)
ksft_exit_fail_msg("mmap returned address above hint with MAP_BELOW_HINT\n");
This is just going to fail because your flags are wrong then wrongly claim to have passed...
- ksft_test_result_pass("MAP_BELOW_HINT works\n");
+}
-- 2.45.0